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Upward shift of the pH optimum of Acremonium ascorbate oxidase
Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 2002A gene encoding a thermostable Acremonium ascorbate oxidase (ASOM) was randomly mutated to generate mutant enzymes with altered pH optima. One of the mutants, which exhibited a significantly higher activity in the pH range 4.5-7 compared to ASOM, had a Gln183Arg substitution in the region corresponding to SBR1, one of the substrate binding regions of ...
Masayasu, Sugino +7 more
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pH optimum of the reduction of dehydroascorbic acid by dithioerytritol
Scandinavian Journal of Clinical and Laboratory Investigation, 1993Ascorbic acid is a water soluble antioxidant, that is itself oxidized to dehydroascorbic acid. In order to detect dehydroascorbic acid by amperometri it has to be reduced to ascorbic acid beforehand. This reduction was performed with dithioerytritol at pH = 6.0 for 10 min, which is a choice between optimal reaction rate and stability of ascorbic acid ...
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A kinetic study of the pH optimum of canine cardiac cathepsin D
Cardiovascular Research, 1980An acid protease, most likely cathepsin D, was purified approximately 1000 fold to homogeneity from canine cardiac tissue using acetate precipitation, affinity chromatography and gel filtration. Molecular weight determinations of the isolated acid protease using gel filtration suggested the presence of a single polypeptide chain of molecular weight ...
E A, Ogunro, A G, Ferguson, M, Lesch
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Protein engineering of chymosin; modification of the optimum pH of enzyme catalysis
"Protein Engineering, Design and Selection", 1990The aspartic proteinase chymosin exhibits a local network of hydrogen bonds involving the active site aspartates and surrounding residues which may have an influence on the rate and optimal pH of substrate cleavage. We have introduced into chymosin B the following substitutions: Asp304 to Ala (D304A), Thr218 to Ala (T218A) and Gly244 to Asp (G244D ...
D, Mantafounis, J, Pitts
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Biochemistry, 2004
The optimum pH of Bacillus cereus beta-amylase (BCB, pH 6.7) differs from that of soybean beta-amylase (SBA, pH 5.4) due to the substitution of a few amino acid residues near the catalytic base residue (Glu 380 in SBA and Glu 367 in BCB). To explore the mechanism for controlling the optimum pH of beta-amylase, five mutants of BCB (Y164E, Y164F, Y164H ...
Akira, Hirata +3 more
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The optimum pH of Bacillus cereus beta-amylase (BCB, pH 6.7) differs from that of soybean beta-amylase (SBA, pH 5.4) due to the substitution of a few amino acid residues near the catalytic base residue (Glu 380 in SBA and Glu 367 in BCB). To explore the mechanism for controlling the optimum pH of beta-amylase, five mutants of BCB (Y164E, Y164F, Y164H ...
Akira, Hirata +3 more
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Altering the substrate specificity site of Aspergillus niger PhyB shifts the pH optimum to pH 3.2
Applied Microbiology and Biotechnology, 2007Phytases are of biotechnological importance as animal feed additives for their ability to catalyze the hydrolysis of phosphate from phytate for absorption by simple-stomached animals, and to reduce their fecal phosphorus excretion. Aspergillus niger PhyB has high catalytic activity at low pHs around 2.5, but has little activity at the commonly observed
Jeremy D, Weaver +2 more
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Agents and Actions, 1993
Stromelysin-1 was purified from human articular cartilage and compared to synovial fibroblast enzyme and to recombinant enzyme. If the latent enzyme was incubated at pH 5.5 with substrates such as aggrecan, it spontaneously became active. Incubation of latent zymogen alone at pH 5.5 gave increasing activation over a period of at least 5 hours. However,
Z, Gunja-Smith, J F, Woessner
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Stromelysin-1 was purified from human articular cartilage and compared to synovial fibroblast enzyme and to recombinant enzyme. If the latent enzyme was incubated at pH 5.5 with substrates such as aggrecan, it spontaneously became active. Incubation of latent zymogen alone at pH 5.5 gave increasing activation over a period of at least 5 hours. However,
Z, Gunja-Smith, J F, Woessner
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Susceptibilities of Mycobacterium malmoense determined at the growth optimum pH (pH 6.0).
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 1998Pulmonary disease caused by Mycobacterium malmoense is increasing. Conventional in vitro antimicrobial susceptibilities correlate poorly with response to treatment for this organism. Radiometrically determined minimum inhibitory concentrations (MICs) allow quantitative susceptibility testing for non-tuberculous mycobacteria. The M.
M L, Heginbothom +2 more
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Zur Frage des pH-Optimums des Pepsins
Experientia, 1961Natural and purified proteins were split by crystallized pepsin. The break down of substrates was followed by a turbidimetric method. pH optima were found from 1.5 to 3.8. Only unpurified egg albumin had two optima, crystallin had one in the acid range. Ovomucoid not being split by pepsin, the second peak at pH 3.79 is referred to conalbumin. While the
S. Buchs, E. Freudenberg
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The optimum pH of adsorbed ribonuclease
Biochimica et Biophysica Acta, 1959L B, BARNETT, H B, BULL
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