PH optimum, enzyme

Source of enzyme pH optimum pH stability Temperature optimum (°C) Temperature of complete thermal inactivation (°C)... 

D-2-Acetamido-2-deoxyhexosidase has been purified from an edible mushroom, Tremella fuciformis, to a single protein band (mol. wt. 1.25 x 10 by gel filtration) on disc gel electrophoresis. The enzyme (pH optimum 5.0, 0,19... 

The isolation, purification, and characterization of oc-D-mannosidase from cultures of Aspergillus flavus has been described.The enzyme (pH optimum 4.2-4.5) was isolated from the growth medium of the mold at the beginning of the stationary phase of growth and partly purified by ion-exchange chromatography. The effect of temperature and cations on the activity of the enzyme and the effect of pH on its stability were examined for 4-nitrophenyl a-D-mannopyranoside 1.4 mM, the value of the sedimentation constant is. y o = 4.5 S, and the partial specific volume q = 0.725 cm g" ). 

An enzyme (pH optimum 5.6) that debranches branched D-glucans has been isolated from . coli by ion-exchange chromatography. It hydrolysed the... 

Five a-D-galactosidases have been identified by chromatography and polyacrylamide disc-gel electrophoresis in the germinated seeds of white clover Trifolium repens). One of the enzymes (pH optimum 4.0, mol. wt. 4.1— 4.3 X 10 by sodium dodecyl sulphate-polyacrylamide gel idectrophoresis) was studied in further detail and was shown to possess D-galactosyltransferase activities. 

The amounts of a-D-glucosidase in cells of Bacillus amyloliquefaciens grown on amylaceous polysaccharides were found to be higher than in cells grown on non-carbohydrate carbon sources. By subcellular fractionation and solubilization studies, the a-D-glucosidase was exclusively found to be associated with membranes from ruptured spheroplasts. The purified enzyme (pH optimum 6.8, mol. wt. 2.7 0.1 x 10, temperature optimum 39 °Q hydrolysed maltose, maltotriose, isomaltose, and isomaltotriose at rates slower than for 4-nitrophenyl a-D-glucopyranoside and sucrose. 

Neuraminidase activity has been demonstrated in highly concentrated preparations of human para-influenza 1 virus (HA2 virus). The enzyme (pH optimum 5.0—5.4, temperature optimum 37—40 °C, Km 5 mM for iV-acetylneuraminlactose) was found to be thermolabile, and exhibited some characteristics similar to those of neuraminidases from other paramyxoviruses (Sendai, NDV, mumps, human para-influenza 2 virus). 

Conditions for the maximum yield of extracellular a-amylase from Bac-teroides amylophilus have been reported. Isoelectric focusing and polyacrylamide gel electrophoresis demonstrated the presence of six isoenzymes one of these was purified by ion-exchange chromatography and gel filtration. This enzyme (pH optimum 6.3, temperature optimum 43 °C, pH stability range 5.8—7.5, p7 4.6, mol. wt. 9.2 x 10 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis) was inhibited by cyclo-hexa and hepta-amyloses, phenyl a-D-glucopyranoside, and Hg + whereas Ca + and Co were strong activators. The relative rates of hydrolysis of amylose, soluble starch, amylo-pectin, and dextrin were 100, 97, 92, and 60%, respectively (Am values 18.2, 18.7, 18.2, and 16.7 [xmol D-glucosidic bonds 1, respectively). 

A celluloytic enzyme isolated from a commercial cellulase preparation from Aspergillus niger, and which contained no carbohydrate, was found to be active towards carboxymethylcellulose but inactive towards cellobiose and 4-nitrophenyl jS-o-glucopyranoside, The enzyme (pH optimum 3.9, mol. wt. 2.6 X 10 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis) according to kinetic studies had groups with pK values between 4.2 and 5.3 involved in the enzyme-substrate complex. 

Ungerminated pollen of Nicotiana tabacum has been shown to contain a pectolytic enzyme (pH optimum ca. 6.0) which was devoid of pectin lyase activity. ... 

The compound 3, 6-bis(dimethylaminomethyl) catechol is a powerful catalyst of penicillin hydrolysis. Many of the characteristics of its cata.-lytic activity resemble those observed with a number of hydrolytic enzymes (pH optimum, presence of an intermediate, structural specificity necessary for optimum activity, basicity of the amine, susceptibility of the p-lactam to nucleophilic attack and role of the penicillin side chain in the interaction with the catalyst). The results obtained explain satisfactorily the high resistance level of cephalosporins to penicillinase Sb ... 

An intracellular a-amylase (mol. wt. 9.6 x 10 ) from a Pseudomonas species has been purified to homogeneity by fractional precipitation, ion-exchange chromatography, and gel filtration. This e db-enzyme (pH optimum 5.5,... 

Dextranase has been obtained from a strain of Brevibacterium fuscum by fractional precipitation, gel filtration, and ion-exchange chromatography. " The enzyme (pH optimum 7.0—7.5) was stable over a wide pH range (5.0—11.0) and was activated by L-cysteine and H4edta, whereas it was inhibited by iodine, mercuric chloride, A-bromosuccinimide, and cupric sulphate. Since the hydrolysis of dextran by the enzyme afforded principally isomaltotriose, the enzyme appears to be a new ew-dextranase. 

A j8-D-2-acetamido-2-deoxyglucosidase from E. coli has been purified to near homogeneity by electrophoresis on polyacrylamide gel in the presence of sodium dodecyl sulphate and urea. Studies of the substrate specificity of the purified enzyme (pH optimum 7.7, Km (for 4-nitrophenyl 2-acetamido-2-deoxy-l3-D-gluco-pyranoside 0.43 mmol 1 ) confirmed that it has an exo-action. The molecular weight (determined by gel filtration and by gel electrophoresis) of the enzyme in a dissociating medium is 2.6 x 10, showing that it does not contain subunits. 

Three j8-D-2-acetamido-2-deoxyhexosidases have been isolated from culture filtrates of a Streptococcus species by affinity chromatography on agarose derivatized with oxamic acid or l-thio- -o-galactopyranose. The enzymes (pH optimum 5.0—5.5) hydrolysed synthetic substrates and glycopeptides, but not glycolipids. 

An a-D-galactosidase from a strain of E. coli, which was adapted to synthesize the enzyme, was stable in concentrated, but not in dilute, solution. The enzyme (pH optimum 6.8, temperature optimum 37 °C, Km for 4-nitrophenyl a-D-galacto-pyranoside, melibiose, and raffinose 1.07 x 10, 2.33 x 10 , and 3.65 x 10 moll S respectively) also possesses weak glycosyltransferase activity. 

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