Search PubMed⌕ Search

Biomedical subjects

A Gertler

Publications and source records attributed to A Gertler.

At least 145 records · Page 8Linked to original sources
PubMed1980

Stoichiometry of interaction of chicken ovoinhibitor with pancreatic trypsin, chymotrypsin and elastase I.

1. The interaction of chicken ovoinhibitor with pancreatic trypsin, chymotrypsin and elastase I was studied in the absence of substrate by affinity chromatography, electrophoresis and gel filtration. 2. It was found that ovoinhibitor has, at least, five separate and non-overlapping binding sites: two for trypsin, two for chymotrypsin and one for elastase. Most likely, all five sites may be occupied simultaneously. 3. Electrophoretic studies indicated that two binding sites for trypsin and probably also for chymotrypsin differ in their affinity toward the respective enzyme.

Animals↗
PubMed1979

Maleylation and pH-dependence of Streptomyces griseus protease B.

The enzymatic activity of Streptomyces griseus protease B (SGPB) was measured over pH range 8.4--11.5 using a specific new, chromophoric substrate N-succinyl-glycyl-glycyl-L-phenylalanine p-nitroanilide. It was found that the activity is dependent on ionization of a single group with apparent pK = 10.84, possibly lysine-125. Maleylation of the epsilon-amino group of this lysine was linearily associated with the loss of enzymatic activity. It is therefore suggested that the electrostatic interaction between the side chain of lysine-125 and the alpha-carboxyl group of the C-terminal tyrosine is crucial to the active conformation of the enzyme. In contrast the maleylation of the alpha-amino group of the N-terminal isoleucine was rapid but could not be correlated to the loss of activity.

Furans↗
PubMed1979

Significance of urinary enzymes in gestosis.

The levels of five enzymes were examined in the urine and the serum of pregnant women. They included leucine aminopeptidase (LAP), alkaline phosphatase (AP), N-acetyl-beta-glucosaminidase (ABG), lactic acid dehydrogenase (LDH) and glutamic-oxaloacetic transaminase (GOT). After establishing the normal curve and upper confidence limits in healthy pregnant patients (138 examinations in 52 women), the the enzymes were examined in the urine and the serum of 21 severe and 23 mildly toxemic cases. The mean urinary levels of ABG, AP and LAP in the severe cases were significantly higher than in the normals, and by examining all three enzymes, at least one of them was found to be above the upper confidence limit in 95% of the severely ill women. The changes did not show up early enough to form a good diagnostic and prognostic sign in moderate pregnancy-induced hypertension, but severe kidney damage may be revealed earlier than by the regular kidney function tests, and patients with a bad remote prognosis can be singled out by this method.

Acetylglucosaminidase↗
PubMed1978

Enhancement of alpha-chymotrypsin-catalyzed hydrolysis of specific p-nitroanilide substrates by 4-phenylbutylamine derivative of hen egg-white lysozyme.

Modification of hen egg-white lysozyme by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide in presence of 4-phenylbutylamine yielded derivatives, which contained 0.6--0.7 modified residues and retained about 60% of the original activity. Kinetic studies revealed that the modified-lysozyme increases approx. 20-fold the kcat of hydrolysis of SucGly2Phe-4-nitroanilide by alphachymotrypsin, without changing the Km. The apparent dissociation constant of phenylbutylamine-modified lysozyme . chymotrypsin complex was found to be 0.03 mM and independent of substrate concentration. The accelerating effect of the modified lysozyme was also observed with other p-nitroanilide substrates of alpha-chymotrypsin. However, the hydrolysis of other substrates, acylation by active site titrant or inhibition by irreversible or competitive inhibitors were uneffected. The enhancing effect of the modified lysozyme seems to be very specific since other chymotrypsin-like enzymes, or serine proteinases except delta-chymotrypsin, were not influenced and phenylbutylamine derivatives of alpha-lactalbumin or ribonuclease were lacking any enhancing effect. Smaller, but significant enhancing effect was found also in lysozyme substituted by benzylamine, beta-phenylethylamine and tryptamine and in inactive derivatives of lysozyme substituted by phenylbutylamine. Competitive inhibitors of lysozyme such as N-acetyl-D-glucose amine oligomers, (GlcNAc)2 and (GlcNAc)3 abolished partially the accelerating effect of phenylbutylamine-modified lysozyme, indicating that the substituted group is located in the vicinity of the binding site.

Anilides↗
PubMed1977

Effect of oxidation of methionine residues in chicken ovoinhibitor on its inhibitory activities against trypsin, chymotrypsin, and elastase.

Oxidation of methionine residues of chicken ovoinhibitor with N-chlorosuccinimide resulted in a selective loss of its inhibitory activities. While trypsin inhibiting activity was not affected at all, half of the chymotrypsin-inhibiting activity and all of the elastase inhibiting activity were lost. Electrophoretic and affinity chromatography studies indicated that the 50% loss of the chymotrypsin-inhibiting activity resulted from the inactivation of one of its two chymotrypsin-inhibiting sites rather than from a decrease in the binding constants of both sites. Oxidation of ovoinhibitor-chymotrypsin and ovoinhibitor-elastase complexes with excess of N-chlorosuccinimide indicated that the complex formation in each case protected the site that binds the enzyme which participated in the complex, but did not protect the site that binds the other enzyme. Quantitative estimation of the number of oxidized methionine residues in the ovoinhibitor isolated from the complexes has shown that in each complex about one methionine residue was protected from oxidation. Nitrophenyl-sulfenylation of the single tryptophan residue of ovoinhibitor did not affect its inhibitory activities at all.

Animals↗
PubMed1976

The comparative effect of prolonged feeding with raw and heated soybean mean on the growth response, pancreatic enlargement and pancreatic enzymes of chicks.

Prolonged feeding of chicks with raw soybean meal as the main protein source in the diet resulted in growth inhibition, pancreas enlargement, and increased content of pancreatic proteolytic enzymes. The effect of feeding with raw soybean meal as compared to heated soybean meal upon total intestinal enzymatic activities in chicks was tested. The tendency of chicks to overcome the effects of raw soybean meal is expressed mainly by the increase of biosynthesis and secretion of proteolytic enzymes in the pancreas.

Amylases↗
PubMed1975

Aspergillus oryzae acid proteinase. Purification and properties, and formation of pi-chymotrypsin.

An acid proteinase from Aspergillus oryzae was isolated from a commercial powder by successive (NH4)2SO4 fractionation, acetone precipitation, and ion-exchange chromatography on phosphate- and DEAE-cellulose columns. The purified enzyme was found to be homogeneous by ultracentrifuge-sedimentation analysis (S20, W equal 3.63S), but electrofocusing in polyacrylamide gels and electrophoresis at pH 3.2 revealed that it consists of two very closely migrating bands. No difference in the amino acid composition and enzymic activities of the two partially separated bands could be detected, and it was concluded that the acid proteinase exists in two molecular forms. The enzyme activates bovine trypsinogen and chymotrypsinogen at pH 3.5 (the kappacat. and Km values at 35degrees C are 11.3S- minus 1, 0.10mM and 1.14S- minus 1, 0.18mM respectively). It hydrolyses the Phe-Phe bond of the synthetic pepsin substrates Z-His-Phe-Phe-OEt (kappacat. equal 1.65S- minus 1, Km equal 0.640mM at pH 3.5, 30degrees C) and Z-Ala-Ala-Phe-Phe-OPy4Pr (kappacat. equal 0.37S- minus 1, Km equal 0.037 mM at pH2.9, 39degrees C), where Z represents benzyloxycarbonyl and OPy4Pr represents 3-(4-pyridyl)-propyl 1-ester. Activation of bovine chymotrypsinogen results from the cleavage of the Arg(15)-Ile(16) bond in the zymogen. No other cleavages were observed. The use of A. oryzae proteinase provides a simple tool for the production of pi-chymotrypsin in good yield and purity.

Amino Acids↗