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Many Enzymes (many + enzyme)
Selected AbstractsTerpenoid Indole Alkaloids Biosynthesis and Metabolic Engineering in Catharanthus roseusJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 7 2007Dong-Hui Liu Abstract Catharanthus roseus L. (Madagascar periwinkle) biosynthesizes a diverse array of secondary metabolites including anticancer dimeric alkaloids (vinblastine and vincristine) and antihypertensive alkaloids (ajmalicine and serpentine). The multi-step terpenoid indole alkaloids (TIAs) biosynthetic pathway in C. roseus is complex and is under strict molecular regulation. Many enzymes and genes involved in the TIAs biosynthesis have been studied in recent decades. Moreover, some regulatory proteins were found recently to control the production of TIAs in C. roseus. Based on mastering the rough scheme of the pathway and cloning the related genes, metabolic engineering of TIAs biosynthesis has been studied in C. roseus aiming at increasing the desired secondary metabolites in the past few years. The present article summarizes recent advances in isolation and characterization of TIAs biosynthesis genes and transcriptional regulators involved in the second metabolic control in C. roseus. Metabolic engineering applications in TIAs pathway via overexpression of these genes and regulators in C. roseus are also discussed. [source] From Theozymes to Artificial Enzymes: Enzyme-Like Receptors for Michael Additions with Oxyanion Holes and Active Amino GroupsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2007Luis Simón Abstract Different artificial enzymes, based on the theozyme concept, have been designed for Michael additions of pyrrolidine to ,,,-unsaturated lactams. These molecules each have skeleton able to mimic a structure called an "oxyanion hole", as is present in many enzymes. Amine groups are also responsible for the catalytic activities of these receptors, since they support the important proton-transport step. The requirement for the amine groups was established from the reaction mechanism and from theoretical calculations. The catalytic activities of the receptors are discussed, taking into account their relative association constants with the substrate: kcat/kuncat values of up to 104 were obtained. The catalytic activities of the receptors are compared with those found in natural enzymes and catalytic antibodies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Pfnek-1, a NIMA-related kinase from the human malaria parasite Plasmodium falciparumFEBS JOURNAL, Issue 9 2001Biochemical properties, possible involvement in MAPK regulation We have cloned Pfnek-1, a gene encoding a novel protein kinase from the human malaria parasite Plasmodium falciparum. This enzyme displays maximal homology to the never-in-mitosis/Aspergillus (NIMA)/NIMA-like kinase (Nek) family of protein kinases, whose members are involved in eukaryotic cell division processes. Similar to other P. falciparum protein kinases and many enzymes of the NIMA/Nek family, Pfnek-1 possesses a large C-terminal extension in addition to the catalytic domain. Bacterially expressed recombinant Pfnek-1 protein is able to autophosphorylate and phosphorylate a panel of protein substrates with a specificity that is similar to that displayed by other members of the NIMA/Nek family. However, the FXXT motif usually found in NIMA/Nek protein kinases is substituted in Pfnek-1 by a SMAHS motif, which is reminiscent of a MAP/ERK kinase (MEK) activation site. Mutational analysis indicates that only one of the serine residues in this motif is essential for Pfnek-1 kinase activity in vitro. We show (a) that recombinant Pfnek-1 is able to specifically phosphorylate Pfmap-2, an atypical P. falciparum MAPK homologue, in vitro, and (b) that coincubation of Pfnek-1 and Pfmap-2 results in a synergistic increase in exogenous substrate labelling. This suggests that Pfnek-1 may be involved in the modulation of MAPK pathway output in malaria parasites. Finally, we demonstrate that recombinant Pfnek-1 can be used in inhibition assays to monitor the effect of kinase inhibitors, which opens the way to the screening of chemical libraries aimed at identifying potential new antimalarials. [source] Hepatic chemoprotective enzyme responses to 2-substituted selenazolidine-4(R)-carboxylic acidsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 6 2006Wael M. El-Sayed Abstract In epidemiology and human supplementation studies, as well as many animal models, selenium has shown antitumorigenic activity. The mechanism of action, however, has not been satisfactorily resolved. Selenium supplementation affects many enzymes in addition to those where selenocysteine is an essential component. Such enzymes include cytoprotective detoxifying enzymes, and the regulation of these enzymes by a set of 2-substituted selenazolidine-4(R)-carboxylic acids (SCAs) has been investigated. Following seven consecutive daily doses of these prodrugs of L -selenocysteine, changes in hepatic enzyme activities and/or mRNA levels of glutathione transferase (GST), microsomal epoxide hydrolase (mEH), NAD(P)H-quinone oxidoreductase (NQO), UDP-glucuronosyltransferase (UGT), glutathione peroxidase (GPx), and thioredoxin reductase (TR) have been observed. Among the enzymes examined, UGTs and GPx were found to be the least affected. Among the compounds, 2-oxoSCA produced the most changes and 2-phenylSCA produced the least, none. For no two compounds was the pattern of changes identical, and for a single compound, few changes were reproduced in common by the two routes of administration investigated. In general, more changes were elicited following intraperitoneal (i.p.) administration than with the intragastric (i.g.) route. This dominance was typified by 2-butylSCA and 2-cyclohexylSCA where enzyme activity elevations (TR and mEH with both, NQO with 2-butylSCA) were seen only with the i.p. route. With 2-oxoSCA, however, GST, TR, and NQO activities were found to be elevated independent of route. Only with GST (both routes) and TR (i.p. route), elevations in mRNAs accompanied the 2-oxoSCA elicited elevations of activities at the time of sacrifice. For some enzymes, most notably mEH with compounds administered i.p., elevations in mRNAs were not manifest as increased enzyme activity. Thus, although constituting a closely related series of compounds, each 2-substituted SCA produced its own unique pattern of changes, and for most members, changes were predominant following i.p. administration. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:292,301, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20148 [source] Whole Blood Manganese Concentrations in Dogs with Congenital Portosystemic ShuntsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010A.G. Gow Background: Manganese (Mn) is an essential mineral that is a cofactor for many enzymes required in the synthesis of proteins, carbohydrates, and lipids. Because hepatic clearance is essential in Mn homeostasis, conditions in humans resulting in hepatic insufficiency including cirrhosis and both acquired and congenital portosystemic shunting have been reported to result in increased blood Mn concentrations and increased Mn content in the central nervous system. Because Mn toxicity causes neurologic disturbances, increased Mn concentrations have been implicated in the pathogenesis of hepatic encephalopathy. Hypotheses: Dogs with congenital portosystemic shunts (cPSS) have significantly higher whole blood Mn concentrations than do healthy dogs or those with nonhepatic illnesses. Animals: Eighteen dogs with cPSS, 26 dogs with nonhepatic illnesses, and 14 healthy dogs. Methods: Whole blood Mn was measured by graphite furnace atomic absorption spectrometry. The diagnosis of cPSS was made by ultrasonography or during celiotomy either by visual inspection of a shunting vessel or portovenography. Results: Dogs with a cPSS had significantly higher whole blood Mn concentrations than did healthy dogs and dogs with nonhepatic illnesses. Whole blood Mn concentrations were not significantly different between healthy dogs and dogs with nonhepatic illnesses. Conclusion and Clinical Importance: Dogs with a cPSS have significantly increased whole blood Mn concentrations. Additional studies are warranted to investigate the role of Mn in cPSS-associated hepatic encephalopathy. [source] Differential expression of lysosomal associated membrane protein (LAMP-1) during mammalian spermiogenesisMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2003Ricardo D. Moreno Abstract The mammalian acrosome is a secretory vesicle of mature sperms that plays an important role in fertilization. Recent evidence had pointed out that some components found at endosomes in somatic cells are associated with the developing acrosome during the early steps of spermiogenesis. Moreover, the mammalian acrosome contains many enzymes found within lysosomes in somatic cells. In this work, we studied the dynamics of some components of the endosome/lysosome system, as a way to understand the complex membrane trafficking circuit established during spermatogenesis. We show that the cation independent-mannose-6-phosphate receptor (CI-MPR) is transiently expressed in the cytoplasm of mid-stage spermatids (steps 5,11). On the other hand, ,-adaptin, an adaptor molecule of a complex involved in trafficking from the Golgi to lysosomes, was expressed in cytoplasmic vesicles only in pachytene and Cap-phase spermatids (steps 1,5). Our major finding is that the lysosomal protein LAMP-1 is differentially expressed during spermiogenesis. LAMP-1 appears late in spermatogenesis (Acrosome-phase) contrasting with LAMP-2, which is present throughout the complete process. Both proteins appear to be associated with cytoplasmic vesicles and not with the developing acrosome. None of the studied proteins is present in epididymal spermatozoa. Our results suggest that the CI-MPR could be involved in membrane trafficking and/or acrosomal shaping during spermiogenesis. Mol. Reprod. Dev. 66: 202,209, 2003. © 2003 Wiley-Liss, Inc. [source] Proteomics viewed on stress response of thermophilic bacterium Bacillus stearothermophilus,TLS33PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 14 2005Supachai Topanurak Abstract Thermophilic bacterium Bacillus stearothermophilus,TLS33, isolated from a hot spring in Chiang Mai, Thailand, usually produces many enzymes that are very useful for industrial applications. However, the functional properties and mechanisms of this bacterium under stress conditions are rarely reported and still need more understanding on how the bacterium can survive in stress environments. In this study, we examined the oxidative stress induced proteins of this bacterium by proteomic approach combining two-dimensional electrophoresis and mass spectrometry. When the bacterium encountered oxidative stress, peroxiredoxin, as an antioxidant enzyme, is one of the interesting stressed proteins which appeared to be systematically increased with different pI. There are four isoforms of peroxiredoxin, denoted as Prx,I, Prx,II, Prx,III and Prx,IV, which are observed at the same molecular weight of 27,kDa but differ in pI values of 5.0, 4.87, 4.81 and 4.79, respectively. The H2O2 concentration directly increased Prx,II, Prx,III and Prx,IV intensities, but decreased Prx,I intensity. These shifting of peroxiredoxin isoforms may occur by a post-translational modification. Otherwise, the longer time of oxidative stress had not affected the expression level of peroxiredoxin isoforms. Therefore, this finding of peroxiredoxin intends to know the bacterial adaptation under oxidative stress. Otherwise, this protein plays an important role in many physiological processes and able to use in the industrial applications. [source] CYP1A1, SULT1A1, and SULT1E1 polymorphisms are risk factors for endometrial cancer susceptibilityCANCER, Issue 9 2008Hiroshi Hirata MD Abstract BACKGROUND. In estrogen biosynthetic pathways, many enzymes are important for metabolism, detoxification, and bioavailability. Polymorphisms in these genes may have an effect on the enzymes' function. For example, higher expression and activation of biosynthetic enzymes and lower expression and activation of conjugation enzymes may lead to high toxicity or carcinogenesis. The authors hypothesized that single nucleotide polymorphisms (single nucleotide polymorphisms) of CYP1A1, CYP1A2, CYP1B1, CYP17, SULT1A1, SULT1E1, and SHBG genes may be risk factors for endometrial cancer. METHODS. DNA samples from 150 cases of endometrial cancer and healthy controls (n = 165) were analyzed by polymerase chain reaction,restriction fragment length polymorphism (PCR-RFLP) to determine the genotypic frequency of 13 different polymorphic loci on the CYP1A1 (m1, m2, m3, m4), CYP1A2 1F, CYP1B1 codon432, COMT codon158, CYP17, SULT1A1 (Arg213His, 14A/G, 85C/T in the 3, flanking region), SULT1E1-64G/A promoter region, and SHBG genes. Genotyping was validated by direct DNA sequencing. The authors also investigated the relation between expression of CYP1A1 in endometrial cancer tissues and genotypes of CYP1A1 m1. RESULTS. A decreased frequency of TC + CC genotype of the CYP1A1 m1 (T/C) polymorphism was observed in endometrial cancer patients compared with controls (OR = 0.42; 95% CI, 0.27,0.69). The T-A haplotype of CYP1A1 m1 and m2 was increased in endometrial cancer patients (P = .017). The frequency of CYP1A1 m1 T/C + C/C was higher in a high CYP1A1 expression group (P = .009). The authors also found that individuals carrying the variants of SULT1A1 codon213 and 2 single nucleotide polymorphisms in the 3, flanking region (14A/G and 85C/T) had an increased risk for endometrial cancer. The frequencies of G-A-C and A-G-T haplotypes of these 3 variants were higher in endometrial cancer patients (P < .0001; P = .0002). In addition, the frequency of combined genotypes (SULT1A1 213 GA + AA and CYP1A1 m1 TT) was higher in endometrial cancer patients. (OR, 4.58; 95% CI, 2.35,8.93). CONCLUSIONS. This is the first report on the combined association of CYP1A1 and SULT gene polymorphisms in endometrial cancer that suggests a decreased single nucleotide polymorphism of CYP1A1 and an increased single nucleotide polymorphism for SULT1A1 and SULT1E1 genes may be risk factors for endometrial cancer in Caucasians. Cancer 2008. © 2008 American Cancer Society. [source] | ||||||||||||||||