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Microbial Enzymes (microbial + enzyme)
Selected AbstractsEffects of Papain and a Microbial Enzyme on Meat Proteins and Beef TendernessJOURNAL OF FOOD SCIENCE, Issue 6 2002I.N.A. Ashie ABSTRACT: The relative effects of an aspartic proteinase (AP) and papain on meat proteins and beef tenderness were evaluated by measuring release of hydroxyproline in collagen, and breakdown of myofibrillar proteins. Tenderness was objectively measured by Warner-Bratzler shear. AP showed self-limiting hydrolysis of myofibrillar proteins resulting in 25 to 30% improvement in meat tenderness and was not adversely affected by pH, salt, phosphate, and ascorbate concentrations often encountered in meat processing. Like papain, its tenderizing effect was expressed primarily during cooking and caused no ignificant changes (p > 0.05) in tenderness during frozen or refrigerated storage. It was also inactivated at cooking temperatures in excess of 60 °C, therefore eliminating any undesirable side effects that may be associated with residual protease activity. [source] Mixed Aromatic Acyloin Condensations with Recombinant Benzaldehyde Lyase: Synthesis of ,-Hydroxydihydrochalcones and Related ,-Hydroxy KetonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Monica Sanchez-Gonzalez Abstract Recombinant benzaldehyde lyase (BAL), expressed and purified from E.,coli strain JM-109, was used to catalyze the condensation of a series of methoxybenzaldehydes and phenylacetaldehyde in the synthesis of ,-(R)-hydroxydihydrochalcones. Enantiomerically pure 1-hydroxy-1,3-diphenylpropan-2-ones and o -anisoin were also obtained as products of the BAL reaction. The R absolute configurations of chiral centers were determined by CD spectroscopy. ,-(R)-Hydroxydihydrochalcones and 1-hydroxy-1,3-diphenylpropan-2-ones are valuable synthons for chemoenzymatic syntheses of flavonoids. This is the first synthesis of ,-(R)-hydroxydihydrochalcones by a microbial enzyme. [source] Intestinal function and body growth of broiler chickens on maize-based diets supplemented with mimosa tannins and a microbial enzymeJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2004Paul A Iji Abstract A study was conducted to evaluate the effects of tannin (0, 5, 15, 20 and 25 g kg,1 diet) and a microbial enzyme supplement (MES) on the feed consumption, body growth and digestive physiology of broiler chickens between hatch and 22 days of age. Feed intake, body weight and body weight gain declined (p < 0.001) with an increase in dietary tannin content. Feed conversion efficiency was increased (p < 0.001) in line with dietary tannin level, up to 15 g kg,1 diet. There were no significant effects of dietary treatment on the protein content of pancreatic tissue or activities of pancreatic and jejunal enzymes. The ileal digestibilities of energy, protein, arginine, alanine and leucine were reduced (p < 0.001) as dietary tannin level rose to 20 g kg,1 diet and beyond. The digestibilities of methionine and phenylalanine were also negatively affected (p < 0.01) at the highest level of dietary tannins, while phosphorus digestion was improved (p < 0.05) on diets containing tannin. Apart from an increase (p < 0.01) in the protein content of the jejunal mucosa of birds on the diet with 20 g tannin kg,1 diet, there were no significant effects of the MES on most of the variables assessed. The results demonstrate the negative effects of tannin, especially at high levels of inclusion in the diet. However, neither tannins nor MES influenced the activities of digestive enzymes assessed, suggesting that a wider range of factors may be involved in regulating the effects of tannins on poultry. Copyright © 2004 Society of Chemical Industry [source] Biochemical characterization of rice trehalose-6-phosphate phosphatases supports distinctive functions of these plant enzymesFEBS JOURNAL, Issue 5 2007Shuhei Shima Substantial levels of trehalose accumulate in bacteria, fungi, and invertebrates, where it serves as a storage carbohydrate or as a protectant against environmental stresses. In higher plants, trehalose is detected at fairly low levels; therefore, a regulatory or signaling function has been proposed for this molecule. In many organisms, trehalose-6-phosphate phosphatase is the enzyme governing the final step of trehalose biosynthesis. Here we report that OsTPP1 and OsTPP2 are the two major trehalose-6-phosphate phosphatase genes expressed in vegetative tissues of rice. Similar to results obtained from our previous OsTPP1 study, complementation analysis of a yeast trehalose-6-phosphate phosphatase mutant and activity measurement of the recombinant protein demonstrated that OsTPP2 encodes a functional trehalose-6-phosphate phosphatase enzyme. OsTPP2 expression is transiently induced in response to chilling and other abiotic stresses. Enzymatic characterization of recombinant OsTPP1 and OsTPP2 revealed stringent substrate specificity for trehalose 6-phosphate and about 10 times lower Km values for trehalose 6-phosphate as compared with trehalose-6-phosphate phosphatase enzymes from microorganisms. OsTPP1 and OsTPP2 also clearly contrasted with microbial enzymes, in that they are generally unstable, almost completely losing activity when subjected to heat treatment at 50 °C for 4 min. These characteristics of rice trehalose-6-phosphate phosphatase enzymes are consistent with very low cellular substrate concentration and tightly regulated gene expression. These data also support a plant-specific function of trehalose biosynthesis in response to environmental stresses. [source] Kinetics of electron transfer from NADH to the Escherichia coli nitric oxide reductase flavorubredoxinFEBS JOURNAL, Issue 3 2007João B. Vicente Escherichia coli flavorubredoxin (FlRd) belongs to the family of flavodiiron proteins (FDPs), microbial enzymes that are expressed to scavenge nitric oxide (NO) under anaerobic conditions. To degrade NO, FlRd has to be reduced by NADH via the FAD-binding protein flavorubredoxin reductase, thus the kinetics of electron transfer along this pathway was investigated by stopped-flow absorption spectroscopy. We found that NADH, but not NADPH, quickly reduces the FlRd-reductase (k = 5.5 ± 2.2 × 106 m,1·s,1 at 5 °C), with a limiting rate of 255 ± 17 s,1. The reductase in turn quickly reduces the rubredoxin (Rd) center of FlRd, as assessed at 5 °C working with the native FlRd enzyme (k = 2.4 ± 0.1 × 106 m,1·s,1) and with its isolated Rd-domain (k , 1 × 107 m,1·s,1); in both cases the reaction was found to be dependent on pH and ionic strength. In FlRd the fast reduction of the Rd center occurs synchronously with the formation of flavin mononucleotide semiquinone. Our data provide evidence that (a) FlRd-reductase rapidly shuttles electrons between NADH and FlRd, a prerequisite for NO reduction in this detoxification pathway, and (b) the electron accepting site in FlRd, the Rd center, is in very fast redox equilibrium with the flavin mononucleotide. [source] Biochemical characterization of MI-ENG1, a family 5 endoglucanase secreted by the root-knot nematode Meloidogyne incognitaFEBS JOURNAL, Issue 11 2000Christel Béra-Maillet A ,-1,4-endoglucanase named MI-ENG1, homologous to the family 5 glycoside hydrolases, was previously isolated from the plant parasitic root-knot nematode Meloidogyne incognita. We describe here the detection of the enzyme in the nematode homogenate and secretion and its complete biochemical characterization. This study is the first comparison of the enzymatic properties of an animal glycoside hydrolase with plant and microbial enzymes. MI-ENG1 shares many enzymatic properties with known endoglucanases from plants, free-living or rumen-associated microorganisms and phytopathogens. In spite of the presence of a cellulose-binding domain at the C-terminus, the ability of MI-ENG1 to bind cellulose could not be demonstrated, whatever the experimental conditions used. The biochemical characterization of the enzyme is a first step towards the understanding of the molecular events taking place during the plant,nematode interaction. [source] The application of chromogenic media in clinical microbiologyJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2007J.D. Perry Summary Since 1990, a wide range of chromogenic culture media has been made commercially available providing useful tools for diagnostic clinical microbiology. By the inclusion of chromogenic enzyme substrates targeting microbial enzymes, such media are able to target pathogens with high specificity. Examples of target pathogens include Staphylococcus aureus, Streptococcus agalactiae, Salmonella spp. and Candida spp. The inclusion of multiple chromogenic substrates into culture media facilitates the differentiation of polymicrobial cultures, thus allowing for the development of improved media for diagnosis of urinary tract infections and media for the enhanced discrimination of yeasts. The purpose of this review is to provide some insight into how such media work and appraise their utility in routine clinical diagnostics, in comparison with conventional media. [source] | ||||||||||