Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple method for preparing plasma membranes from bovine testes is described. Bovine testicular receptor has a high affinity and specificity for 125I-labelled human FSH (follicle-stimulating hormone). The specific binding of 125I-labelled human FSH to the plasma membranes is a saturable process with respect to the amounts of receptor protein and FSH added. The association and dissociation of 125I-labelled human FSH are time- and temperature-dependent, and the binding of labelled human FSH to bovine testicular receptor is strong and not readily reversible. Scatchard [Ann. N.Y. Acad. Sci. (1949) 51, 660-672] analysis indicates a dissociation constant, Kd, of 9.8 X10(-11)M, and 5.9 X 10(-14)mol of binding sites/mg of membrane protein. The testicular membrane receptor is heat-labile. Preheating at 40 degrees C for 15 min destroyed 30% of the binding activity. Specific binding is pH-dependent, with an optimum between pH 7.0 and 7.5. Brief exposure to extremes of pH caused irreversible damage to the receptors. The ionic strength of the incubation medium markedly affects the association of 125I-labelled human FSH with its testicular receptor. Various cations at concentrations of 0.1M inhibit almost completely the binding of 125I-labelled human FSH. Nuclectides and steroid hormones at concentrations of 1mM and 5mu/ml respectively have no effect on the binding of FSH to its receptor. Incubation of membranes with and chymotrypsin resulted in an almost complete loss of binding activity, suggesting that protein moieties are essential for the binding of 125I-labelled human FSH. Binding of 125I-labelled human FSH to bovine testicular receptor does not result in destruction or degradation of the hormone.
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PMID:Properties of follicle-stimulating-hormone receptor in cell membranes of bovine testis. 24 18

Sertoli cell intracellular protein 1 (SCc1) and 2 (SCc2) are polypeptides found in rat Sertoli cell cultures incubated with either FSH or (Bu)2cAMP. They were first identified in [35S]methionine-labeled Sertoli cell lysates using two-dimensional gel electrophoresis. Here we extend these observations by showing that SCc1 and SCc2 are present in rat seminiferous tubules, ovaries, and granulosa cells incubated with either FSH or (Bu)2cAMP and in testicular peritubular cells incubated with (Bu)2cAMP. Peritubular cells do not, however, respond to FSH with the production of SCc1 and SCc2. Peptide mapping with N-chlorosuccinimide revealed that SCc1 and SCc2 have similar cleavage patterns, suggesting a common primary amino acid sequence that is modified posttranslationally. Metabolic labeling with [32P]orthophosphate provided direct evidence that SCc1 and SCc2 are phosphoproteins. A shift in mobility of SCc1 and SCc2 toward the basic region of the gel to positions designated SCc1' and SCc2' occurred when cell lysates were treated with alkaline phosphatase before electrophoresis, providing additional evidence that SCc1 and SCc2 are phosphoproteins. SCc1 and SCc2 are also shown to be mitochondrially-associated in the Sertoli cell. Peptide maps of SCc1, SCc2, SCc1', and SCc2' obtained by treatment with alpha-chymotrypsin, are identical to proteolytic maps of proteins pp30', p30, and pp30 from adrenocortical cells. SCc1, SCc2, SCc1', and SCc2' are homologous with regard to their regulated expression, electrophoretic mobility, and mitochondrial localization to the adrenal proteins pp30' and pp30 as well as a series of 30 kilodalton proteins from MA-10 Leydig tumor cells. Both the adrenal cell proteins and the Leydig tumor cell proteins are thought to participate in cholesterol transport to the inner mitochondrial membrane, providing substrate for the cholesterol side-chain cleavage enzyme complex, an activity which the Sertoli cell does not perform, suggesting that alternative functions must be sought for SCc1 and SCc2 in Sertoli cells.
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PMID:Follicle-stimulating hormone-regulated Sertoli cell proteins SCc1 and SCc2 are phosphorylated and mitochondrially associated. 133 Apr 90

The effects of various chemical and enzymatic treatments on the biological activity of porcine luteinizing hormone-releasing hormone (LH-RH) are described. This experiment was performed before the elucidation of the structure of LH-RH. LH-RH activity was abolished by the following endopeptidases: chymotrypsin, subtilisin, papain, and thermolysin, but not by pepsin or trypsin. Exopeptidases did not affect LH-RH activity, but a purified preparation of pyrolidone carbosylpeptidase did. The amino acid sequence of LH-RH/FSH-RH was established to be (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-Amine. This decapeptide lacks both the Amine terminus and the COOH terminus. Its Amine-terminal dipeptide sequence,(pyro)Glu-His, is similar to that of tyrotropin-releasing hormone. The lack of inactivation by the exopeptidases is in good agreement with these findings. Treatment with various chemical reagents showed that tyrosine, histidine, tryptophan, and arginine in LH-RH are important for its biological activity. Nitrous acid and Edman degradation did not inactivate LH-RH. These results are also in agreement with the determined structure of LH-RH. This hormone showed a high follicle-stimulating hormone-releasing hormone (FSH-RH) activity. The inactivation of LH-RH was always accompanied by a loss of FSH-RH activity. These experiments also shed some light on the structure-activity relationship of this hormone.
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PMID:Studies on the properties of hypothalamic luteinizing hormone-releasing hormone. 494 14

We investigated the effect of gonadotropins on protease that were suggested to be implicated in the invasive activity of the trophoblast. hCG levels ranging from 10 x 10(3) to 333 x 10(3) IU/L produced a dose-dependent inhibition of the in vitro globinolytic activity of the purified proteases trypsin, chymotrypsin, and urokinase, but failed to inhibit plasmin, collagenase, elastase, and tissue-type plasminogen activator. Likewise, FSH inhibited purified trypsin and urokinase, but not plasmin or tissue-type plasminogen activator. Culture medium conditioned with human trophoblast displayed serine protease and urokinase-like activities; exposure of the cultured trophoblast to exogenous hCG markedly suppressed serine protease and urokinase activities in the conditioned medium. A short treatment of the conditioned medium with trypsin abolished the hCG-mediated inhibition of urokinase activity. The present findings offer an explanation for earlier observations that hCG reduced collagenase activity in trophoblasts without affecting the level of collagenase-specific mRNA. The present results are also consistent with the concept that hCG, by its direct ability to inhibit certain serine proteases and urokinase in trophoblast, suppresses a protease-mediated conversion of procollagenase to active collagenase. The ability of hCG to prevent initiation of the collagenolytic cascade suggests that gonadotropins may regulate the transient invasive activity of the trophoblast.
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PMID:Gonadotropin-mediated inhibition of proteolytic enzymes produced by human trophoblast in culture. 768 89

We investigated the influence of some proteolytic enzymes being present in the digestive canal (pepsin, trypsin, chymotrypsin) on the digestion of porcine FSH-samples by electrophoresis. Trypsin and Chymotrypsin digested the 18-kDa-protein much faster than pepsin, whereas a 67-kDa-protein was much faster digested by Pepsin than by Trypsin or Chymotrypsin. The overall proteolytic effect of Chymotrypsin is small compared with Pepsin and Trypsin. A subsequent digestion with Pepsin, Trypsin and Chymotrypsin led to a complete proteolysis of all proteins being present in the sample.
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PMID:[Electrophoretic analysis on the proteolytic decomposition of of FSH preparations]. 859 40