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Biotransformation
Kinds of Biotransformation Terms modified by Biotransformation Selected AbstractsA Peroxidase-Based Biosensor Supported by Nanoporous Magnetic Silica Microparticles for Acetaminophen Biotransformation and Inhibition StudiesELECTROANALYSIS, Issue 17 2006Donghui Yu Abstract Magnetized nanoporous silica based microparticles (MMPs) were used for horseradish peroxidase (HRP) immobilization and applied for amperometric peroxidase-based biosensor development. A magnetized carbon paste electrode permitted the MMPs attraction. The biosensor was applied to the investigation of the enzymatic oxidation of acetaminophen (paracetamol). The biosensor operated at low applied potential and the signal corresponded to the electroreduction of N -acetylbenzoquinoneimine (NAPQI) generated by the enzyme HRP in the presence of hydrogen peroxide. The biosensor allowed performing the quantitation of acetaminophen in the micromolar concentration range and the comparative study of thiols which inhibited the biosensor response. Distinct inhibition results were observed for HRP entrapped in the silica microparticles compared to the soluble HRP. [source] Enhancement of the NAD(P)(H) Pool in Escherichia coli for BiotransformationENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2007F. Heuser Abstract In pyridine nucleotide-dependent, reductive whole cell biotransformation with resting cells of Escherichia coli, the availability of intracellular NAD(P)(H) is a pivotal point for an efficient and highly productive substrate conversion. The question whether an increase of the intracellular NAD(P)(H) concentration could increase the productivity was discussed controversially in the past. This is the first report on an E. coli strain with an increased NAD(P)(H) pool which was tested in a reductive biotransformation system for an increased productivity. Biotransformation was performed with a strain overexpressing a gene encoding an (R)-specific alcohol dehydrogenase for the stereospecific, NADPH-dependent reduction of methyl acetoacetate (MAA) to (R)-methyl-3-hydroxybutanoate (MHB). Cofactor regeneration was implemented via glucose oxidation by coexpression of a gene encoding glucose dehydrogenase. The specific MHB productivity (mmol mg,1 cell dry weight,1h,1) enabled a comparison between the E. coli,BL21(DE3) wild-type and a genetically modified strain. The enhancement of the NAD(P)(H) pool was achieved by genetic manipulation of the NAD(H) biosynthetic pathways. After simultaneous overexpression of the pncB and nadE genes, encoding nicotinic acid phosphoribosyltransferase and NAD synthetase, measurements of the total NAD(P)(H) pool, sizes showed a 7-fold and 2-fold increased intracellular concentration of NAD(H) and NADP(H), respectively. However, the implementation of an E.,coli strain carrying a genomically integrated pncB gene with an upstream T7,promoter for biotransformation did not result in reproducible increased specific cell productivity. [source] Reduced nicotinamide adenine dinucleotide phosphate and the higher incidence of pollution-induced liver cancer in female flounderENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2003Angela Koehler Abstract In biological effect monitoring programs, induction of biotransformation and detoxification enzymes is used as a biomarker for pollution. Yet sex differences are usually neglected in the availability of reduction equivalents needed in these metabolic pathways and may affect biomarker responses. For example, female flounder have a threefold higher incidence of macroscopic liver nodules than males of the same age class in polluted environments of the North Sea that progress toward carcinomas, whereas tumors in males virtually never develop into cancer. Evidence is presented in this review that NADPH plays a significant role in this sex-related response to xenobiotics in liver of flounder. The NADPH is needed for biosynthesis, particularly of lipids and lipoproteins, and detoxification processes such as one-electron and two-electron biotransformation and conjugation and, therefore, its availability as substrate determines biomarker responses. Biotransformation of xenobiotics is more strongly induced and conjugation processes are less affected in male flounder liver during exposure. In female liver, NADPH is required for production of the yolk precursor protein vitellogenin for oocyte production. The latter process has a higher priority than the NADPH-requiring detoxification processes because reproductive success is more relevant in evolutionary perspectives than the survival of the individual female. The data reviewed here suggest that these sex-related differences in NADPH metabolism are a major cause of the higher incidence of liver cancer in female flounder in polluted environments. [source] Biotransformation of n -hexadecane by cell suspension cultures of Cinchona robusta and Dioscorea compositaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Carolina Vega-Jarquin Abstract This manuscript evaluates the phytotoxicity and biotransformation of n -hexadecane as well as peroxidase activity and cytochrome P450 concentration in microsomes for cell suspension cultures of Cinchona robusta and Dioscorea composita. Phytotoxicity was evaluated based on viability and growth. Cell cultures were exposed to a 2 and 4% (v/v) dose of n -hexadecane. The biotransformation of n -hexadecane was determined based on labeled recovery in polar, nonpolar, and cell residue fractions after cell culture extraction during exponential cell growth phase and stationary phase. Differences were observed in accumulation of label during cell growth phase and stationary phase for the cells of the two plants. Differences also were observed between phases for label in polar and nonpolar fractions. Thin-layer chromatography determined labeled intermediates and some were identified. The activity of peroxidase and concentration of cytochrome P450 was lower in C. robusta than in controls and greater in D. composita than in controls. In vitro biotransformation was not successful. [source] Blocking Fluorine Substitution in Biotransformation of Nortricyclanyl N -Phenylcarbamates with Beauveria bassianaEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003Günter Haufe Abstract The biotransformation of tricyclo[2.2.1.02,6]hept-3-yl N -phenylcarbamate (8) by a standard procedure using Beauveria bassiana gave a 7:1 mixture of optically active exo,exo - and exo,endo -5-hydroxytricyclo[2.2.1.02,6]hept-3-yl N -phenylcarbamates 15 and 16 in 19% isolated yield. No ring opening of the three-membered ring was observed. Substitution with a fluorine atom at the 5- endo - or 5- exo -position prevented hydroxylation of any alicyclic position of the molecules, p -hydroxylation of the aromatic ring occurring to a small extent instead. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Biotransformation of xenobiotics by amine oxidasesFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 2 2001Margherita Strolin Benedetti Although the cytochrome P450 (CYP) system ranks first in terms of catalytic versatility and the wide range of xenobiotics it detoxifies or activates to reactive intermediates, the contribution of amine oxidases and in particular of monoamine oxidases (MAOs) to the metabolism of xenobiotics is far from negligible but has been largely neglected. In this review on the involvement of amine oxidases in the metabolism of xenobiotics, the major characteristics reported for the CYP system (protein, reaction, tissue distribution, subcellular localisation, substrates, inhibitors, inducers, genetic polymorphism, impact of different physiopathological conditions on the activity, turnover) will be compared, whenever possible, with the corresponding characteristics of amine oxidases (MAOs in particular). The knowledge of the involvement of MAO-A, -B or both in the metabolism of a drug allows us to predict interactions with selective or non-selective MAO inhibitors (e.g. the metabolism of a drug deaminated by both forms of MAO is not necessarily inhibited in vivo by a selective MAO-A or -B inhibitor). If a drug is metabolized by MAOs, competitive interactions can occur with other drugs that are MAO substrates, e.g. with ,-adrenoceptor agonists and antagonists, prodrugs of dopamine, serotonin 5-HT1 -receptor agonists as well as with primaquine, flurazepam and citalopram. Moreover, the knowledge of the involvement of MAOs in the metabolism of a drug may suggest possible, although not obligatory, interactions with tyramine-containing food or drink, with over the counter medicines sold to relieve the symptoms of coughs and colds (generally containing the indirectly-acting sympathomimetic amine phenylpropanolamine) or with phenylephrine-containing preparations. Finally, biotransformation by amine oxidases, as by CYP, does not always lead to detoxication but can produce toxic compounds. [source] Biotransformation in vitro of the 22R and 22S epimers of budesonide by human liver, bronchus, colonic mucosa and skinFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 1 2001Julio Cortijo The pharmacological effects of glucocorticoids are greatly influenced by their pharmacokinetic properties. In the present report, the in vitro biotransformation of the 22R and 22S epimers of the topical steroid budesonide was studied in the S-9 fraction of human liver, bronchus, skin and colonic mucosa. The disappearance of unchanged epimers of budesonide was measured during 90 min of incubation by high performance liquid chromatography. The rate of disappearance was high in human liver while little biotransformation occurred in bronchial tissue and colonic mucosa, and none was detected in the skin. A marked decay of the initial concentration of unchanged budesonide epimers was noticed after 2 h incubation in cultured human hepatocytes, while only a small decrease was observed after 24 h incubation in cultured human airway smooth muscle cells and BEAS-2B cells. The 22R epimer of budesonide suffered greater in vitro biotransformation than the 22S epimer in human hepatic, bronchial and colonic tissues. These findings extend those of other studies, and confirm that the high therapeutic ratio of budesonide is due to negligible local biotransformation combined with high level of liver metabolism for locally absorbed budesonide. [source] Metabolism of Deuterated erythro -Dihydroxy Fatty Acids in Saccharomyces cerevisiae: Enantioselective Formation and Characterization of HydroxylactonesHELVETICA CHIMICA ACTA, Issue 6 2008Leif-A. Abstract Epoxides of fatty acids are hydrolyzed by epoxide hydrolases (EHs) into dihydroxy fatty acids which are of particular interest in the mammalian leukotriene pathway. In the present report, the analysis of the configuration of dihydroxy fatty acids via their respective hydroxylactones is described. In addition, the biotransformation of (±)- erythro -7,8- and -3,4-dihydroxy fatty acids in the yeast Saccharomyces cerevisiae was characterized by GC/EI-MS analysis. Biotransformation of chemically synthesized (±)- erythro -7,8-dihydroxy(7,8- 2H2)tetradecanoic acid ((±)- erythro - 1) in the yeast S. cerevisiae resulted in the formation of 5,6-dihydroxy(5,6- 2H2)dodecanoic acid (6), which was lactonized into (5S,6R)-6-hydroxy(5,6- 2H2)dodecano-5-lactone ((5S,6R)- 4) with 86% ee and into erythro -5-hydroxy(5,6- 2H2)dodecano-6-lactone (erythro - 8). Additionally, the , -ketols 7-hydroxy-8-oxo(7- 2H1)tetradecanoic acid (9a) and 8-hydroxy-7-oxo(8- 2H1)tetradecanoic acid (9b) were detected as intermediates. Further metabolism of 6 led to 3,4-dihydroxy(3,4- 2H2)decanoic acid (2) which was lactonized into 3-hydroxy(3,4- 2H2)decano-4-lactone (5) with (3R,4S)- 5=88% ee. Chemical synthesis and incubation of (±)- erythro -3,4-dihydroxy(3,4- 2H2)decanoic acid ((±)- erythro - 2) in yeast led to (3S,4R)- 5 with 10% ee. No decano-4-lactone was formed from the precursors 1 or 2 by yeast. The enantiomers (3S,4R)- and (3R,4S)-3,4-dihydroxy(3- 2H1)nonanoic acid ((3S,4R)- and (3R,4S)- 3) were chemically synthesized and comparably degraded by yeast without formation of nonano-4-lactone. The major products of the transformation of (3S,4R)- and (3R,4S)- 3 were (3S,4R)- and (3R,4S)-3-hydroxy(3- 2H1)nonano-4-lactones ((3S,4R)- and (3R,4S)- 7), respectively. The enantiomers of the hydroxylactones 4, 5, and 7 were chemically synthesized and their GC-elution sequence on Lipodex®E chiral phase was determined. [source] Biotransformation of Vermitaline by Cunninghamella echinulataHELVETICA CHIMICA ACTA, Issue 5 2008Yi-Feng Lü Abstract Biotransformation of vermitaline (1) by Cunninghamella echinulata (ACCC 30369) was carried out. Four biotransformation products were obtained and three of them were characterized as new compounds. On the basis of their NMR and mass-spectral data, their structures were characterized as 7, -hydroxyrubijervine (2), 7, -hydroxyrubijervine-7-O- , - D -galactofuranoside (3), 7, -hydroxyvermitaline (4), and 7, -hydroxyvermitaline-7-O- , - D -galactofuranoside (5). [source] On the Mechanism of Biotransformation of the Anthraquinonic Dye Acid Blue 62 by LaccasesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Luciana Pereira Abstract We used the recombinant CotA-laccase from the bacterium Bacillus subtilis to investigate the biotransformation of the commercial anthraquinonic dye Acid Blue 62. Kinetics of dye biotransformation at pH,6 follow a Michaelis,Menten model. NMR and several MS techniques allowed the identification of intermediates and final products of the enzymatic biotransformation. The main final product obtained, 1-[(4-amino-9,10-dioxo-3-sulfo-9,10-dihydroanthracen-1-yl)diazenyl]-4-cyclohexylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonic acid, is formed through the creation of an azo link and has been previously identified as an intermediate compound in the biodegradation of Acid Blue 62 by crude fungal preparations. The identification of 1,4-diamino-9,10-dioxo-3-sulfo-9,10-dihydroanthracene-2-sulfonic acid and of cyclohexanone, in reaction mixtures with CotA-laccase and also its presence in reactions performed with the LAC3 laccase from the fungus Trametes sp. C30, suggest the occurrence of coupling reactions between the intermediate products of dye oxidation. Based on these results, we propose a mechanistic pathway for the biotransformation of Acid Blue 62 by laccases. A bioassay based on the inhibitory effects of the dye and its enzymatic products on the growth of Saccharomyces cerevisiae shows the importance of laccases in reducing dye toxicity. [source] FDB2 encodes a member of the arylamine N -acetyltransferase family and is necessary for biotransformation of benzoxazolinones by Fusarium verticillioidesJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009A.E. Glenn Abstract Aims:, To clone and characterize genes from the mycotoxigenic fungus, Fusarium verticillioides, which are associated with its ability to biotransform allelopathic benzoxazolinones produced by maize, wheat, and rye. Methods and Results:, Suppression subtractive hybridization identified F. verticillioides genes up-regulated in response to 2-benzoxazolinone (BOA), including a cluster of genes along chromosome 3. One of these genes, putatively encoding an arylamine N -acetyltransferase (NAT), was highly represented in the subtracted library and was of particular interest since previous analyses identified the FDB2 locus as possibly encoding transferase activity. The gene was subcloned and complemented a natural fdb2 mutant. Conversely, disruption of the gene eliminated the ability of F. verticillioides to metabolize BOA. Other genes in the cluster also were assessed using a complementation assay. Metabolic profiles of fdb2 mutants suggest that minor acylation activity occurred independently of the NAT activity encoded by FDB2. Conclusions:, The previously defined FDB2 locus was functionally associated with the gene encoding putative NAT activity, and the FDB2 gene was essential for biotransformation of BOA. The flanking gene FDB3 encodes a putative Zn(II)2Cys6 transcription factor and contributes to efficient BOA biotransformation but was not essential. Significance and Impact of the Study:, Biotransformation of benzoxazolinones by F. verticillioides may enhance its ecological fitness in maize field environments and our results provide greater understanding of the genes that modulate the biotransformation process. Additionally, this is the first homologue of the NAT gene family to be characterized in a filamentous fungus. [source] Biotransformation of l -menthol by twelve isolates of soil-borne plant pathogenic fungi (Rhizoctonia solani) and classification of fungiJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2003Mitsuo Miyazawa Abstract The microbial transformation of l -menthol (1) was investigated by using 12 isolates of soil-borne plant pathogenic fungi, Rhizoctonia solani (AG-1-IA Rs24, Joichi-2, RRG97-1; AG-1-IB TR22, R147, 110.4; AG-1-IC F-1, F-4, P-1; AG-1-ID RCP-1, RCP-3, and RCP-7) as a biocatalyst. Rhizoctonia solani F-1, F-4 and P-1 showed 89.7,99.9% yields of converted product from 1, RCP-1, RCP-3, and RCP-7 26.0,26.9% and the other isolates 0.1,12.0%. In the cases of F-1, F-4 and P-1, substrate 1 was converted to (,)-(1S,3R,4S,6S)-6-hydroxymenthol (2), (,)-(1S,3R,4S) -1-hydroxymenthol (3) and (+)-(1S,3R,4R,6S)-6,8-dihydroxymenthol (4), which was a new compound. Substrate 1 was converted to 2 and/or 3 by RRG97-1, 110.4, RCP-1, RCP-3 and RCP-7. The structures of the metabolic products were elucidated on the basis of their spectral data. In addition, metabolic pathways of the biotransformation of 1 by Rhizoctonia solani are discussed. Finally, from the main component analysis and the differences in the yields of converted product from 1, the 12 isolates of Rhizoctonia solani were divided into three groups based on an analysis of the metabolites. Copyright © 2003 Society of Chemical Industry [source] Biotransformation of benzaldehyde to L -phenylacetylcarbinol (L -PAC) by Torulaspora delbrueckii and conversion to ephedrine by microwave radiationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2002Vilas B Shukla Abstract In a 5,dm3 stirred tank reactor, bioconversion of 30,g benzaldehyde by cells of Torulaspora delbrueckii yielded 22.9,g of pure L -phenylacetylcarbinol (L -PAC). Facile functional group transformation of 4.5,g of L -PAC to 2-(methylimino)-1-phenyl-1-propanol by exposure to microwave irradiation for 9,min resulted in 2.48,g of product. Conversion of 4.8,g of 2-(methylimino)-1-phenyl-1-propanol to 3.11,g of ephedrine was achieved by exposure to microwaves in a reaction time of 10,min. The identity of all the products was confirmed by 1H NMR and FT-IR analysis. © 2002 Society of Chemical Industry [source] Effect of Lactulose on Biotransformation of Isoflavone Glycosides to Aglycones in Soymilk by LactobacilliJOURNAL OF FOOD SCIENCE, Issue 3 2008T.T. Pham ABSTRACT:,Lactobacillus acidophilus 4461, L. acidophilus 4962, L. casei 290, and L. casei 2607 were used to hydrolyze isoflavone glycosides (IG) to biologically active forms,isoflavone aglycones (IA),in soymilk (SM) prepared from soy protein isolate (SPI) and soymilk supplemented with 0.5% (w/v) of lactulose (SML). L. acidophilus 4461 utilized the highest level of lactulose (3.01 mg/mL) and L. acidophilus 4962 utilized the least (0.86 mg/mL) at 24 h of incubation. The pH values decreased to 4.00 to 5.00 in SML, while they remained relatively high (6.15 to 6.36) in SM. Supplementation with lactulose significantly (P < 0.05) enhanced the viable counts of all the 4 Lactobacillus strains. At the end of incubation, the viable counts of Lactobacillus ranged from 8.08 to 8.25 log CFU/mL in SML compared to 6.99 to 7.11 log CFU/mL in SM. Supplementation with lactulose increased the biotransformation of IG to IA after 6 h of incubation. The presence of lactulose in the medium enhanced the biotransformation level of IG to IA by Lactobacillus up to 21.9%. The hydrolysis level of malonyl genistin and acetyl genistin in SML was much higher than in SM by all the 4 probiotic organisms. The biotransformation of IG to IA occurred rapidly during the 1st 12 h of incubation in both SML and SM. Among the 4 Lactobacillus strains, L. acidophilus 4461 biotransformed the highest level (88.8%) of IG to IA in SML compared to 68.2% in SM after 24 h of incubation. [source] Biotransformation of Isoflavone Glycosides by Bifidobacterium animalis in Soymilk Supplemented with Skim Milk PowderJOURNAL OF FOOD SCIENCE, Issue 8 2007T.T. Pham ABSTRACT:, Two probiotic strains, Bifidobacterium animalis A and B, were used for the biotransformation of isoflavone glycosides in soymilk prepared from soy protein isolate (SPI) supplemented with skim milk powder (SMP) (SSMP). Unsupplemented soymilk (USM) and reconstituted skim milk powder (RSMP) were used as controls. The numbers of viable microorganisms in these products were enumerated. Lactose and isoflavone contents were quantified using high-performance liquid chromatography (HPLC). Our results showed that there was significantly higher biotransformation of isoflavone glycosides to aglycones in SSMP than that in USM. The levels of biotransformation were 83.96% and 85.43% for B. animalis A and B, respectively, compared to 74.30% and 72.82% for the USM. In addition, lactose utilization by both strains in SSMP was also higher than that in RSMP. At 24 h, 21.16 mg/mL of lactose was utilized in SSMP by B. animalis A compared with that of 16.88 mg/mL in RSMP. Consequently, the pH of SSMP was lower (3.80) than RSMP (4.00). However, the number of viable bacteria in SSMP was slightly lower than that in RSMP but significantly higher than that in USM. It appears that SMP enhanced the biotransformation of isoflavone glycosides to aglycones and SPI increased the lactose utilization by B. animalis A and B. [source] Biotransformation of Isoflavones by Bifidobacteria in Fermented Soymilk Supplemented with D-Glucose and L-CysteineJOURNAL OF FOOD SCIENCE, Issue 2 2003D. Tsangalis ABSTRACT: Soymilk prepared using soy-protein isolate supplemented with D-glucose and L-cysteine was fermented with 4 strains of Bifidobacterium. Enumeration of bifidobacteria and quantification of isoflavones using HPLC were performed at 0, 12, 24, 36, and 48 h of incubation. Supplementation did not significantly enhance (p > 0.05) the growth of bifidobacteria between 0 and 12 h, but did after 12 h. The increase in concentration of isoflavone aglycones and equol was significantly lower (p < 0.05) in supplemented soymilk after 24 h when compared to plain soymilk. Supplementation increased the concentration of aglycones by 0.796 mg/100 mL in soymilk fermented with B. animalis between 12 and 24 h, and the population by 1.27 log10 CFU/mL (p < 0.05). [source] Biotransformation of 4-Hydroxybenzen Derivatives by Hairy Root Cultures of Polygonum multiflorum Thunb.JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2007Chun-Yan Yan Abstract The biotransformation of four 4-hydroxybenzen derivatives (1,4-benzenediol (compound 1), 4-hydroxybenzaldehyde (compound 2), 4-hydroxybenzyl alcohol (compound 3) and 4-hydroxybenzoic acid (compound 4)) by the hairy root cultures of Polygonum multiflorum Thunb. as a new biocatalyst was investigated. It was found that the substrates were transformed to their corresponding glucosides, 4-hydroxyphenyl ,- D -glucopyranoside (arbutin, compound 1a), 4-hydroxymethylphenyl ,- D -glucopyranoside (gastrodin, compounds 2a, 3a) and 4-carboxyphenyl ,- D -glucopyranoside (compound 4a), respectively. In the meantime, the hairy roots of P. multiflorum were able to stereoselectively and regioselectively glucosylate phenolic hydroxyl groups of compounds 1,4, but the cultures could not glucosylate the aldehyde group of compound 2 or the benzylic hydroxyl group of compound 3, and no glucosyl esterification of carboxyl groups of compound 4 was detected. On the other hand, the result also showed that the hairy roots of P. multiflorum were able to reduce the 4-hydroxybenzaldehyde to its corresponding alcohol. This is the first report that substrate 4 has been converted into its ,- D -glucopyranoside by a plant biotransformation system. [source] Biotransformation of the triketone herbicide mesotrione by a Bacillus strain.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2006Metabolite profiling using liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry The metabolic pathway involved in the biotransformation of the herbicide mesotrione by the bacterial strain Bacillus sp. 3B6 was investigated by a reliable liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS) method. The LC/ESI-MS method, both in positive and negative mode, with the assistance of MS2 fragments and isotopic pattern analyses, allowed us to identify five metabolites. This work constitutes the first complete monitoring of mesotrione degradation kinetics. Among the transformation products found by both techniques, one was formed by intramolecular cyclization between a hydroxylamine and a keto function, which is quite a rare biological reactivity process. For each identified metabolite, a fragmentation pathway is proposed for negative and positive mode. Copyright © 2006 John Wiley & Sons, Ltd. [source] Innentitelbild: Biotransformation an Polymer-Peptid-Konjugaten , ein universelles Werkzeug zur Mikrostrukturkontrolle (Angew. Chem.ANGEWANDTE CHEMIE, Issue 35 200935/2009) Das BioSwitch-Konzept nutzt eine posttranslationale Modifikation, um den hierarchischen Aufbau von Mikrostrukturen zu regulieren. Wie H.,G. Börner und H. Kühnle in der Zuschrift auf S.,6552,ff. beschreiben, unterdrückt der Einbau von phosphorylierten Threoninresten in das Peptidsegment eines Polymer-Peptid-Konjugats dessen Selbstorganisation höchst effektiv. Die saure Phosphatase trennt die Phosphatgruppen vom Peptidsegment ab, aktiviert die Funktion der ,-Faltblatt-Aggregationsdomäne und löst damit die Selbstorganisation aus. [source] Biotransformation an Polymer-Peptid-Konjugaten , ein universelles Werkzeug zur Mikrostrukturkontrolle,ANGEWANDTE CHEMIE, Issue 35 2009Hans Kühnle Nützlicher Störenfried: Der Einbau von O -Phosphatestern in (Thr-Val)x -Aggregationsdomänen stört den Aufbau von Sekundärstrukturen nachhaltig. Dies kann genutzt werden, um die Selbstorganisation von Polymer-Peptid-Konjugaten zu regulieren. Phosphatasen, die selektiv die Hydrolyse von Phosphatestern katalysieren, schalten die Selbstorganisation und damit die Bildung von fibrillären Strukturen an (siehe Schema). [source] Biotransformation of tuna waste by co-fermentation into an aquafeed ingredientAQUACULTURE RESEARCH, Issue 9 2009Hena Vijayan Abstract Dried skipjack tuna (Katsuwonus pelamis) waste (red meat, gills, viscera, fins, etc.) were mixed with 25% wheat flour and inoculated with a starter culture of Lactobacillus plantarum National Collection of Industrial Microorganisms (NCIM) 2912 (108,109 cells mL,1) and Bacillus licheniformis MTCC 6824 (107,108 cells mL,1). Changes in the nutritional quality (crude protein, crude fat, crude ash, crude fibre and nitrogen-free extract and aminoacids) were monitored during a fermentation period of 14 days. The proximate analysis showed significant changes in the composition of L. plantarum -fermented tuna (LPFT) and B. licheniformis -fermented tuna (BLFT) from the unfermented raw materials. Fermentation of tuna waste has resulted in a significant (P<0.05) increase in the protein content of tuna waste between days 6 and 12. All the amino acid contents in BLFT increased during fermentation, whereas, in LPFT the levels of serine, histidine, tyrosine, methionine, cystine and phenylalanine contents were decreased. A marginal increase in calcium and phosphorus levels was recorded in the fermented products. The results of the study suggest that LPFT or BLFT can be used as a novel aquafeed ingredient for different fish species. [source] Liquid chromatography,tandem mass spectrometry for the identification of l -tetrahydropalmatine metabolites in Penicillium janthinellum and ratsBIOMEDICAL CHROMATOGRAPHY, Issue 1 2006Li Li Abstract l-Tetrahydropalmatine (l-THP) is an active alkaloid from Stephania ainiaca Diels. In order to compare the similarities and differences of microbial and mammalian metabolisms of l-THP, the microbial transformation by Penicillium janthinellum and metabolism in rats were investigated. Biotransformation of l-THP by Penicillium janthinellum AS 3.510 resulted in the formation of three metabolites. Their structures were identified as l-corydalmine, l-corypalmine and 9- O -desmethyl-l-THP, respectively, by comprehensive nuclear magnetic resonance and mass spectrometry (MS) analysis. Six metabolites (M1,M6) were detected from the in vivo study in rats and three of which (l-corydalmine, l-corypalmine and 9- O -desmethyl-l-THP) were identified as the same compounds as those obtained from microbial metabolism by liquid chromatography,tandem mass spectrometry (LC-MS[sol ]MS) analysis and comparison with reference standards obtained from microbial metabolism. The structures of the additional three metabolites were tentatively deduced as 2- O -desmethyl-l-THP and two di- O -demethylated l-THP by LC-MS[sol ]MS analysis. Time courses of microbial and rat metabolisms of l-THP were also investigated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Human cytochromes mediating gepirone biotransformation at low substrate concentrationsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2003David J. Greenblatt Abstract Biotransformation of gepirone to 1-(2-pyrimidinyl)-piperazine (1-PP) and 3'-OH-gepirone, as well as two other hydroxylated metabolites, was studied in vitro using a human liver microsomal preparation and heterologously expressed human CYP3A4 and CYP2D6. The focus was on a low range of gepirone concentrations (1000 nM and below). Liver microsomes formed 1-PP and 3'-OH-gepirone with similar reaction velocities. Two other hydroxylated metabolites (2-OH- and 5-OH-gepirone) were also formed, but pure reference standards were not available for purposes of quantitative analysis. The CYP3A inhibitor ketoconazole completely eliminated 1-PP formation, reduced 3'-OH-gepirone formation to less than 20% of control, and reduced 2-OH-gepirone formation to 7% of control. All metabolites were formed by expressed CYP3A4; however, CYP2D6 formed 3'-OH- and 5-OH-gepirone, but not 1-PP or 2-OH-gepirone. Based on estimated relative abundances of the two isoforms in human liver, CYP3A4 was predicted to account for more than 95% of net clearance of gepirone in vivo at low concentrations approaching the therapeutic range. CYP2D6 would account for less than 5% of net clearance. The findings are consistent with previous in vitro studies of gepirone using higher substrate concentrations. Copyright © 2003 John Wiley & Sons, Ltd. [source] Biotransformation of R -2-hydroxy-4-phenylbutyric acid by D -lactate dehydrogenase and Candida boidinii cells containing formate dehydrogenase coimmobilized in a fibrous bed bioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2005Yunling Bai Abstract R -2-hydroxy-4-phenylbutyric acid (R-HPBA) is an important intermediate in the manufacture of angiotensin converting enzyme inhibitors. In this work, a recombinant D -lactate dehydrogenase (LDH) was used to transform 2-oxo-4-phenylbutyric acid (OPBA) to R-HPBA, with concomitant oxidation of ,-nicotinamide adenine dinucleotide (NADH) to NAD+. The cofactor NADH was regenerated by formate dehydrogenase (FDH) present in whole cells of Candida boidinii, which were pre-treated with toluene to make them permeable. The whole cells used in the process were more stable and easier to prepare as compared with the isolated FDH from the cells. Kinetic study showed that the reaction rate was dependent on the concentration of cofactor, NAD+, and that both R-HPBA and OPBA inhibited the reaction. A novel method for co-immobilization of whole cells and LDH enzyme on cotton cloth was developed using polyethyleneimine (PEI), which induced the formation of PEI,enzyme,cell aggregates and their adsorption onto cotton cloth, leading to multilayer co-immobilization of cells and enzyme with high loading (0.5 g cell and 8 mg LDH per gram of cotton cloth) and activity yield (,>,95%). A fibrous bed bioreactor with co-immobilized cells and enzyme on the cotton cloth was then evaluated for R-HPBA production in fed-batch and repeated batch modes, which gave relatively stable reactor productivity of 9 g/L,·,h and product yield of 0.95 mol/mol OPBA when the concentrations of OPBA and R-HPBA were less than 10 g/L. © 2005 Wiley Periodicals, Inc. [source] Biotransformation of Cycloalkanediones by Caragana chamlagu.CHEMINFORM, Issue 16 2003Wen Chai Abstract For Abstract see ChemInform Abstract in Full Text. [source] Biotransformation of flobufen enantiomers in ruminant hepatocytes and subcellular fractionsCHIRALITY, Issue 10 2001Lenka Skálová Abstract Flobufen (F), a new antiinflammatory drug, has one chiral and one prochiral center in its structure. Reduction of rac - F, the principal biotransformation pathway, leads to the formation of four diastereoisomers of 4-dihydroflobufen (DHF). F was chosen as a model substrate for interspecies comparison of activity, stereospecificity, and stereoselectivity of biotransformation enzymes in fallow bucks, red deer stags, and roe bucks in vitro. Formation of F metabolites was examined in hepatocyte suspension and in subcellular fractions of liver homogenate. (+)-R -F, (,)-S -F and rac - F were used as substrates. After incubation of substrates, the amounts and ratios of DHF diastereoisomers and F enantiomers were assessed by HPLC, with (R,R)-ULMO and terguride-bonded columns. Considerable interspecies differences in stereoselectivity and stereospecificity of F reductases were found at the cellular and subcellular levels, although these ruminants are closely related. Chiral inversion of F enantiomers to their antipodes was detected in vitro in all ruminants tested, but individual species also differed in the direction and rate of this inversion. Chirality 13:760,764, 2001. © 2001 Wiley-Liss, Inc. [source] Enhancement of the NAD(P)(H) Pool in Saccharomyces cerevisiaeENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2008A. Knepper Abstract Asymmetric biosyntheses allow for an efficient production of chiral building blocks. The application of whole cells as biocatalysts for asymmetric syntheses is advantageous because they already contain the essential coenzymes NAD(H) or NADP(H), which additionally can be regenerated in the cells. Unfortunately, reduced catalytic activity compared to the oxidoreductase activity is observed in many cases during whole-cell biotransformation. This may be caused by low intracellular coenzyme pool sizes and/or a decline in intracellular coenzyme concentrations. To enhance the intracellular coenzyme pool sizes, the effects of the precursor metabolites adenine and nicotinic acid on the intracellular accumulation of NAD(H) and NADP(H) were studied in Saccharomyces cerevisiae. Based on the results of simple batch experiments with different precursor additions, fed-batch processes for the production of yeast cells with enhanced NAD(H) or enhanced NADP(H) pool sizes were developed. Supplementation of the feed medium with 95,mM adenine and 9.5,mM nicotinic acid resulted in an increase of the intracellular NAD(H) concentration by a factor of 10 at the end of the fed-batch process compared to the reference process. The final NAD(H) concentration remains unchanged if the feed medium was solely supplemented with 95,mM adenine, but intracellular NADP(H) was increased by a factor of 4. The effects of NADP(H) pool sizes on the asymmetric reduction of ethyl-4-chloro acetoacetate (CAAE) to the corresponding (S)-4-chloro-3-hydroxybutanoate (S-CHBE) was evaluated with S.,cerevisiae,FasB,His6 as an example. An intracellular threshold concentration above 0.07,mM NADP(H) was sufficient to increase the biocatalytic S-CHBE productivity by 25,% compared to lower intracellular NADP(H) concentrations. [source] Enhancement of the NAD(P)(H) Pool in Escherichia coli for BiotransformationENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2007F. Heuser Abstract In pyridine nucleotide-dependent, reductive whole cell biotransformation with resting cells of Escherichia coli, the availability of intracellular NAD(P)(H) is a pivotal point for an efficient and highly productive substrate conversion. The question whether an increase of the intracellular NAD(P)(H) concentration could increase the productivity was discussed controversially in the past. This is the first report on an E. coli strain with an increased NAD(P)(H) pool which was tested in a reductive biotransformation system for an increased productivity. Biotransformation was performed with a strain overexpressing a gene encoding an (R)-specific alcohol dehydrogenase for the stereospecific, NADPH-dependent reduction of methyl acetoacetate (MAA) to (R)-methyl-3-hydroxybutanoate (MHB). Cofactor regeneration was implemented via glucose oxidation by coexpression of a gene encoding glucose dehydrogenase. The specific MHB productivity (mmol mg,1 cell dry weight,1h,1) enabled a comparison between the E. coli,BL21(DE3) wild-type and a genetically modified strain. The enhancement of the NAD(P)(H) pool was achieved by genetic manipulation of the NAD(H) biosynthetic pathways. After simultaneous overexpression of the pncB and nadE genes, encoding nicotinic acid phosphoribosyltransferase and NAD synthetase, measurements of the total NAD(P)(H) pool, sizes showed a 7-fold and 2-fold increased intracellular concentration of NAD(H) and NADP(H), respectively. However, the implementation of an E.,coli strain carrying a genomically integrated pncB gene with an upstream T7,promoter for biotransformation did not result in reproducible increased specific cell productivity. [source] Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed ReactorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006M. Ergezinger Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source] Persistent or not persistent?ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2009Polychlorinated biphenyls are readily depurated by grizzly bears (Ursus arctos horribilis) Abstract Major pharmacokinetic processes influencing polychlorinated biphenyl (PCB) accumulation in mammals include uptake, biotransformation, respiration, and excretion. We characterized some of the factors underlying PCB accumulation/loss by evaluating PCB concentrations and patterns in pre- and posthibernation grizzly bears (Ursus arctos horribilis) and their prey. The PCB congeners with vicinal meta - and para -chlorine unsubstituted hydrogen positions consistently showed loss both before and during hibernation, supporting the idea of a dominant role for biotransformation. Retention of all other studied congeners relative to that of PCB 194 varied widely (from <1 to 100%) and was highly correlated with log octanol--water partition coefficient (p < 0.0001). A lack of loss for most of these other congeners during hibernation supports the notion that excretion (e.g., fecal or urinary) or lack of uptake during the feeding season underlies their lack of accumulation, because hibernating bears do not eat or excrete. We estimate that grizzly bears retain less than 10% of total PCBs taken up from their diet. Our results suggest that for grizzly bears, depuration of PCBs via biotransformation is important (explaining ,40% of loss), but that nonbiotransformation processes, such as excretion, may be more important (explaining ,60% of loss). These findings, together with the approximately 91% loss of the persistent PCB 153 congener relative to PCB 194 in grizzly bears, raise important questions about how one defines persistence of PCBs in wildlife and may have bearing on the interpretation of food-web biomagnification studies. [source] | |||||||||||||||||||||||||||||||