pH For Enzyme Reaction Research Articles

Karakterisasi Enzim Komersial Siklodekstrin Glukanotransferase

The objective of this study is to investigate the characteristic of commercial enzyme Cyclodextrin Glucanotrasferase (CGTase) from Bacillus macerans. The CGTase was purified by dialysis, gel fitration and ion exchange chromatography. Study on Characterization of the enzyme showed that the hydrolytic activity of CGTase was 480 U/mg, the optimum tempetature and pH for enzyme reaction were 450C to 550C and pH 5.0 to 8.0, respectively. The CGTase was relatively stable after heating at 550C for 10 minutes, and maintained its activity at the pH 5.0 to 9.0. The enzyme activity was inhibited by the presence of 1 mM metal ions and cause CGTase lost approximately 40% of its activity. Among the metal ions it was found that Cu2+ was the strongest inhibitor, with presence of 1mM Cu2+ the residual activity of CGTase was 24.4%. Results of purification showed that Specific activities of the enzyme during purification were 269 U/mg (crude enzyme); 955 U/mg (dialysis); 481 U/mg (gel fitrations); and 544 U/mg (ion exchange chromatography).

Fibrinolytic and collagenolytic activity of extracellular proteinases of the strains of micromycetes Aspergillus ochraceus L-1 and Aspergillus ustus 1

It was shown that extracellular proteinases produced by the strains of micromycetes A. ochraceus L-1 and A. ustus 1 differ by the activity at various pH as well as by the intensity of the effect on fibrillar proteins. It was revealed that the proteinases of A. ochraceus L-1 demonstrated maximum activity during the growth of the producer in the nitrate-free growth medium (the pH of enzyme reaction was 8.0), whereas those of A. ustus 1 showed maximal activity during the growth of the micromycete in the medium containing sodium nitrate (the pH of enzyme reaction was 6.0). Values of specific fibrinolytic and collagenolytic activities of A. ochraceus L-1 were 2.2 and 1.6 times higher than those of A. ustus 1. At the same time, A. ustus 1 showed very low values of total proteolytic (caseinolytic) activity and had a high ratio of fibrinolytic activity to total proteolytic (caseinolytic) activity (6.92). It makes the strain a promising producer of proteinases, which hydrolyze fibrin and collagen.

Activity and kinetic properties of phosphotransacetylase from intestinal sulfate-reducing bacteria

Phosphotransacetylase activity and the kinetic properties of the enzyme from intestinal sulfate-reducing bacteria Desulfovibrio piger and Desulfomicrobium sp. has never been well-characterized and has not been studied yet. In this paper, the specific activity of phosphotransacetylase and the kinetic properties of the enzyme in cell-free extracts of both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains were presented at the first time. The microbiological, biochemical, biophysical and statistical methods in this work were used. The optimal temperature and pH for enzyme reaction was determined. Analysis of the kinetic properties of the studied enzyme was carried out. Initial (instantaneous) reaction velocity (V0), maximum amount of the product of reaction (Pmax), the reaction time (half saturation period, τ) and maximum velocity of the phosphotransacetylase reaction (Vmax) were defined. Michaelis constants (Km) of the enzyme reaction (3.36 ± 0.35 mM for D. piger Vib-7, 5.97 ± 0.62 mM for Desulfomicrobium sp. Rod-9) were calculated. The studies of the phosphotransacetylase in the process of dissimilatory sulfate reduction and kinetic properties of this enzyme in intestinal sulfate-reducing bacteria, their production of acetate in detail can be perspective for clarification of their etiological role in the development of the humans and animals bowel diseases. These studies might help in predicting the development of diseases of the gastrointestinal tract, by providing further details on the etiology of bowel diseases which are very important for the clinical diagnosis of these disease types.

Improved mannanase production from Penicillium humicola and application for hydrolysis property

Objectives The aim of this research is to produce β-mannanases from a new microbial source using wastes in their nutrition medium. The enzyme produced can be used for the production of galactomanno-oligosaccharides, which are very useful in the health and medical fields. Materials and methods Seven fungal strains and five bacterial strains were tested for the production of β-mannanases. Enzyme activity, protein content, and biomass production were determined in all the cultures produced using standard methods. Optimization studies to maximize enzyme production from the most potent microorganisms, including culture conditions and medium compositions, were also carried out. Preliminary studies for the production of galactomanno-oligosaccharides from locust bean gum using partially purified enzymes were also carried out and followed by thin-layer chromatography techniques and Somogyi methods. Results and conclusion The highest mannanase activities were produced by Penicillium humicola (8.8 U/ml) and Penicillium spp. v (7.75 U/ml) in shaking cultures after 10 days using gum locust bean as a carbon source. Among 13 carbon sources examined, coffee residue and ceratonia seeds were the best carbon sources (10.3 and 8.9 U/ml, respectively) for P. humicola, whereas the best nitrogen source was a mixture of peptone, urea, and ammonium sulfate for the same microorganism. The optimum temperature and pH for enzyme reaction was 55 and 5.5°C, respectively. The enzyme was thermostable and retained 80% of its activity after 1 h at 50°C. The highest reducing sugar of 8900 μg/ml was obtained from locust bean gum hydrolytes after 28 h.