ABSTRACT
Seven p-nitroaniline-modified peptides were used as substrates for studies of aminopeptidase and peptidase activities in eggs of lake salmon Salmo salar Sebago at different stages of embryogenesis. The formation of p-nitroaniline during peptide hydrolysis was measured in the incubation medium and in maturing eggs. Activities of all studied aminopeptidases and peptidases increased during the development of fertilized eggs and sharply increased before hatching. L-alanin-p-NA, L-pro-p-Na, L-Arg-p-Na, and L-Phe-p-NA were hydrolyzed most of all, while N-Glt-L-Phe-p-NA and Z-Gly-Pro-p-NA least of all.
Subject(s)
Aminopeptidases/metabolism , Embryonic Development/physiology , Ovum/enzymology , Peptides/metabolism , Salmo salar/metabolism , Aminopeptidases/chemistry , Animals , Embryo, Nonmammalian , Female , Molecular Weight , Peptides/chemistry , Salmo salar/embryology , Substrate SpecificityABSTRACT
The results of the present study describe the course of reaction and the products following chymotrypsin treatment of the oxytocin analogue carbetocin ([1-deamino-1-monocarba-2-O-methyltyrosine]-oxytocin). The metabolites were analyzed and identified through TLC, HPLC and mass spectrometry. The main product emerging after treatment of carbetocin with chymotrypsin is 9-desglycineamide carbetocin indicating preferential hydrolysis of the peptide bond between leucine at position 8 and carboxyterminal glycineamide. At the same time the stability of the bond between tyrosine at position 2 and isoleucine at position 3 appears significantly enhanced through the alkylation of the hydroxyl group of tyrosine.
Subject(s)
Chymotrypsin/chemistry , Oxytocics/chemistry , Oxytocin/analogs & derivatives , Chromatography, High Pressure Liquid , Chymotrypsin/analysis , Delayed-Action Preparations , Drug Interactions , Glycine/analogs & derivatives , Glycine/analysis , Glycine/chemistry , Injections, Intravenous , Oxytocics/analysis , Oxytocin/analysis , Oxytocin/chemistry , Tyrosine/chemistryABSTRACT
The effect of pesticides on nontarget organisms was studied by following their effect on enzymes from these organisms in vitro. s-Triazines substituted in positions 2, 4, and 6 behaved as inhibitors of plant and animal lactate dehydrogenase, acting competitively with respect to the coenzyme. The inhibition constants were of the order of 10(-3) M and the structure of the substituents exerted no pronounced effect on the inhibition type and the value of the inhibition constant. Polycyclic chlorinated hydrocarbons were found to be much stronger inhibitors, with inhibition constants of the order of 10(-5) M. These substances inhibit the reaction catalyzed by lactate dehydrogenase not only by reaction with the enzyme, but also by a probable direct reaction with the coenzyme.
Subject(s)
Glycine max/enzymology , Hydrocarbons, Chlorinated/pharmacology , L-Lactate Dehydrogenase/antagonists & inhibitors , Pesticides/pharmacology , Triazines/pharmacology , Animals , Cattle , Enzyme Activation/drug effects , In Vitro Techniques , L-Lactate Dehydrogenase/metabolism , Myocardium/enzymology , NADP/metabolism , Glycine max/drug effects , Structure-Activity RelationshipABSTRACT
The interaction of lactate dehydrogenase with high-molecular-weight derivatives of AMP was studied by affinity electrophoresis in an alkaline buffer system and by means of kinetic measurements. AMP was coupled to synthetic hydroxypropylmethacrylamide copolymers through glycine, 6-aminohexanoic and 12-aminododecanoic spacer arms. The values of the dissociation constants (K) of the lactate dehydrogenase isoenzymes--immobilized AMP complexes determined by affinity electrophoresis decreased with increasing length of the spacer arm. Lactate dehydrogenase was competitively inhibited by high-molecular-weight derivatives of AMP; values of the inhibition constants (Ki) also depended on the spacer arm: the longer the spacer arm the stronger was the interaction between the enzyme and the inhibitor. Ki values for high-molecular weight derivatives of AMP were lower than those obtained for free AMP.
Subject(s)
Adenosine Monophosphate/analogs & derivatives , L-Lactate Dehydrogenase/metabolism , Adenosine Monophosphate/metabolism , Animals , Dogs , Electrophoresis/methods , Myocardium/metabolismABSTRACT
Interaction of several enzymes (pyruvate kinase, myokinase, creatine kinase, aldolase, malate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase and glucose-6-phosphate dehydrogenase) and other proteins (bovine serum albumin and ovalbumin) with Blue Dextran was studied by means of affinity electrophoresis in polyacrylamide gels. A decrease of electrophoretic mobility of enzymes in affinity gels was dependent on Blue Dextran concentration and in some cases, dissociation constants of the protein-immobilized dye complexes could be calculated. Affinity electrophoresis in the presence of Blue Dextran reveals in some cases additional bands of isoenzymes, as compared with the control gels (without Blue Dextran).
