Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Regression of MTW9 mammary carcinoma, which consistently follows withdrawal of mammotropic hormones, was characterized by a rapid decrease of thymidine incorporation into DNA but only a slight reduction or uridine incorporation into RNA and amino acid incorporation into proteins. Within 24 hr of hormone withdrawal, cytosol proteins of MTW9 became more easily degraded by trypsin, alpha-chymotrypsin, or subtilisin BPN'. Labilization of cytosol proteins occurred much earlier than any change in the level of protein synthesis or lysosomal enzyme activity. The data showing increased susceptibility to proteolysis could not be explained either by the presence of endogenous proteases, by the destruction of the exogenous proteases used in the assay, or by the existence of protease inhibitors. Nor were any differences detected either in the distribution of radioactive precursor among the cytosol proteins from growing or regressing tumors or in the electrophoretic pattern of the same proteins. Preincubation of the cytosol proteins with dithiothreitol or with prolactin, 17 beta-estradiol, progesterone, and hydrocortisone did not modify the susceptibility to proteolysis. However, after heat denaturation, cytosol proteins of regressing and growing tumors became equally susceptible to proteolysis. It is suggested that regression of MTW9 mammary carcinoma occurs not only because cell reproduction is arrested, but also because susceptibility of cytosol proteins to proteolysis is increased.
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PMID:Increased susceptibility of cytosol proteins to proteolytic digestion during regression of a hormone-dependent mammary tumor. 83 67

The C-terminal undecapeptide of ovine prolactin, H-Leu-Asn-Cys-Arg-Ile-Ile-Try-Asn-Asn-Asn-Cys-OH possesses several structural features common to protein proteinase inhibitors, yet has no inhibitor properties. The undecapeptide is completely hydrolysed by trypsin (Arg-Ile bond) and by chymotrypsin (Tyr-Asn bond), with a proteolytic coefficient of approximately 3,000 M-1 sec-1 and 240 M-1 sec-1 respectively. On the basis of these results, a consideration of entropy, and studies by other workers, we agree with the view of Nishino et al. that the best models for small synthetic peptides with inhibitor properties would be those naturally-occurring inhibitors whose reactive site is located within a small disulphide loop.
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PMID:A study of proteinase inhibition by simulation of inhibitor reactive site regions: interaction of the C-terminal undecapeptide of ovein prolactin with some proteinases. 85 30

Different tissues of the black sea bream Mylio macrocephalus including the liver, gills, intestine, muscle, gonad, swim bladder, spleen, heart and kidney were examined for the presence of prolactin and growth hormone receptors. Membranes were prepared from the tissues and 125I-labeled ovine prolactin and bovine growth hormone were used as ligands. It was found that the liver contained the highest level of specific 125I-labeled ovine prolactin and bovine growth hormone binding, suggesting the existence of hepatic prolactin and growth hormone receptors. The protein nature of the hepatic growth hormone receptor was revealed by the reduction of specific 125I-labeled growth hormone binding after treatment of hepatic membranes with trypsin and chymotrypsin.
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PMID:The sea bream liver contains receptors for growth hormone and prolactin. 141 25

Disordered growth and glucose metabolism secondary to growth hormone deficiency is associated with persistent lymphocytic choriomeningitis virus (LCMV) infection. C3H/St, BALB/WEHI, and SWR/J mice infected at birth with LCMV:ARM carried virus in their blood and organs throughout life but only C3H/St mice developed growth hormone insufficiency. BALB/WEHI and SWR/J infected mice contained normal amounts of growth hormone in their pituitaries and a relatively small proportion of the cells containing growth hormone replicated the virus. In susceptible C3H/St mice, the disease-causing viral strains (LCMV:ARM, E-350, and Pasteur) replicated to higher titers and infected the vast majority of cells producing growth hormone in the anterior lobe of the pituitary. In contrast, LCMV strains Traub and WE replicated in far fewer growth hormone-producing cells and failed to disorder growth hormone synthesis. In another paper (Y. Riviere, R. Ahmed, P. Southern, and M. B. A. Oldstone (1985), Virology 142, 175-182) these findings are used to make reassortants between LCMV:ARM (disease positive) and LCMV:WE (disease nil) and the pathogenic effect is mapped to the small RNA segment of LCMV:ARM. Peptides cleaved by trypsin and chymotrypsin from growth hormone molecules isolated from infected cells or control cells were equivalent when examined by two-dimensional electrophoresis. Further, transfer of antibody to interferon failed to alter the growth hormone insufficiency in these mice, although it corrected LCMV-induced liver disease of BALB mice, suggesting that interferon did not play a dominant role in this disease. The selective tropism of LCMV:ARM for cells containing growth hormone over cells that contain prolactin was observed in both infected animals and in cultured GH-3 cells.
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PMID:Perturbation of differentiated functions during viral infection in vivo. I. Relationship of lymphocytic choriomeningitis virus and host strains to growth hormone deficiency. 241 1

Partial proteolytic digestion of the mammary prolactin (PRL) receptor was used to generate receptor fragments and analyze their immunoreactivity and PRL binding properties. Tryptic digestion of the PRL receptor produced two immunoreactive fragments (Mr approximately 30,000 and approximately 15,000) that reacted with a monoclonal anti-PRL receptor antibody and still specifically bound PRL, while the complete immunoreactive PRL binding unit (Mr approximately 42,000) disappeared. Neither chymotrypsin nor V8 protease were able to generate any immunoreactive receptor fragments. These receptor fragments may represent smaller PRL binding receptor form(s) of biological significance.
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PMID:Partial proteolytic digestion of the mammary prolactin receptor: identification of smaller prolactin binding fragments. 270 Nov 77

A pure preparation of a peptide inhibiting at low (nm-pcm) concentrations a de novo synthesis of prolactin and its secretion into the medium during incubation of rat adenohypophysial tissue has been isolated from cattle hypothalamus. The biological action of the inhibitor differs from that of the already known inhibitors of adenohypophysial hormone secretion--dophamine and somatostatin. The loss of activity by the preparation after treatment with chymotrypsin is indicative of a peptide nature of the inhibitor. The amino acid composition and the N-terminal sequence of the peptide demonstrate its structural similarity to Leu-enkephaline.
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PMID:[Purification and properties of a hypothalamic peptide inhibiting prolactin secretion in vitro]. 610 17

It has been previously demonstrated that commercial bacterial fibrinolysin (EC 3.4.21.7) selectively cleaves the bond between Met-53 and Ala-54 in ovine prolactin (199 amino acids). A one-step purification procedure on DEAE-cellulose for Protease F, which is the active component of bacterial fibrinolysin, and properties of the purified enzyme are reported. The enzyme is homogeneous as judged by acrylamide gel electrophoresis. Its molecular weight, calculated from gel filtration experiments on Sephadex G-100, is around 13,800. Amino acid analyses do not reveal the presence of any half-cystines. The presence of one tryptophan residue per enzyme molecule was resolved from the fluorescence spectrum. Amino terminal analysis showed that leucine was at the amino terminal position. Protease F hydrolyzes casein and synthetic specific substrates for chymotrypsin and elastase esterases but not for trypsin esterases. It is fully inhibited by phenylmethylsulfonyl fluoride, by chicken ovoinhibitor, and by Chymotrypsin Inhibitor I from potatoes but not by the trypsin-chymotrypsin inhibitors from soybeans and chick peas or by tosyl-L-phenylalanine chloromethyl ketone. The enzyme is stable at room temperature and in the cold, it is not affected by dialysis or by freezing and thawing, but it is inactivated during freeze-drying. The circular dichroism spectra of Protease F indicate an approximate 20% alpha-helix content of the enzyme with a considerable similarity to those of subtilisin, elastase, and beta-trypsin. The relatively low molecular weight of Protease F, the absence of intrachain disulfide bridges, and the fact that it is inhibited by several, but not all, chymotrypsin inhibitors suggest that it may differ phylogenetically from the known serine proteases.
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PMID:Purification and properties of protease F, a bacterial enzyme with chymotrypsin and elastase specificities. 622 44

A fraction increasing water and sodium absorption in rat duodenum was detected in the material obtained at an early stage of purification of the hitherto isolated duodenal hormones. In Wistar rats, duodenal loops were made in situ and filled with a solution containing 0.138 mM NaCl, with 14C PEG and 22Na as markers; the final content was collected after 1 h and the movements of water and Na measured. In contrast to secretin, cholecystokinin, and somatostatin, which induced duodenal secretion, and with pentagastrin, which induced duodenal absorption and stimulated acid secretion, this fraction induced duodenal absorption f Na and water without stimulating acid secretion. The fraction was obtained by chromatography of a concentrate of intestinal peptides in 0.2 M acetic acid on Sephadex G25 (fine), and its active component was found to be methanol-soluble at pH4 and insoluble at pH7.5. It was eluted from carboxymethylcellulose 22 with 0.04 M ammonium bicarbonate and gel filtration of Sephadex G50 *fine), resulting in a tenfold increase in activity. Incubation with chymotrypsin suppressed the biological activity, indicating a peptidic nature. The substance displayed biological and radioimmunological properties distinct from those of the gastrointestinal hormones. Particularly, no cross-reactivity was found with gastrin, prolactin, and angiotensin, which are known to increase intestinal absorption. It therefore seems possible that the activity described is due to a peptide that has as yet not been isolated. The name 'sorbin' is proposed for this active principle.
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PMID:Sorbin, a peptide contained in porcine upper small intestine which induces the absorption of water and sodium in the rat duodenum. 679 42

The occurrence of multiple forms of rat prolactin with different molecular weights (size heterogeneity) was studied with anterior pituitary extracts, purified rat prolactin and 125I-labelled rat prolactin. In each case, three main forms of the hormone were detected by gel filtration on Sephadex G-100: a major one (80--90%) corresponding to monomeric prolactin (mol.wt. 22000--25000), a peak (8--20%) that could be a dimer (mol.wt. 45000--50000) and a small quantity (1--5%) of a component of much greater molecular weight. On freezing and thawing of 125I-labelled rat prolactin, there was little interconversion of monomer and 'dimer' peaks, but both were converted substantially to very high-molecular-weight material. All three peaks of 125I-labelled rat prolactin could be precipitated by anti-(rat prolactin) serum and all three gave similar patterns of radioactive peptides after digestion with chymotrypsin followed by high-voltage paper electrophoresis. On sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the monomer peak of 125I-labelled prolactin migrated as a single component of mol.wt. 22000, the very high-molecular-weight peak largely dissociated to a component running in the same position as the monomer, and the 'dimer' peak migrated partly as a component of mol.wt. 45000 and partly as a component migrating with monomeric prolactin. No treatment was found that could dissociate the 'dimer' peak completely to monomeric prolactin.
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PMID:Size heterogeneity of rat pituitary prolactin. 721 47

The effect of prolactin on the digestive potency of the acinar pancreas was examined in pituitary-grafted hyperprolactinemic mice, because our previous experiment showed that a marked proliferation of pancreatic acinar cells was induced by pituitary grafting in mice. To know whether the digestive function is modified, the tissue contents of pancreatic digestive enzymes, such as chymotrypsin, lipase alpha-amylase and ribonuclease, were measured in the hyperprolactinemic mice. Pituitary grafting significantly increased the contents of chymotrypsin and lipase in the pancreas on day 12 after the operation without affecting intake of food, when compared to those in the sham-operated controls. On day 30, however, the differences between pituitary-grafted and control mice were no more discernible. Thus, the digestive enzyme activities are easily modified soon after the increase of circulating prolactin level. This effect of prolactin on the function of the pancreas may be responsible for "homeorhetic" control of nutrients during lactation. In another set of experiments in adrenalectomized-castrated or castrated mice, pituitary grafting induced an increase in the weight of the pancreas. In addition, adrenalectomy in combination with castration did not alter the pancreatic contents of chymotrypsin and lipase but decreased the amylase content. These results taken together seem to indicate that the effect of prolactin on the exocrine pancreas is not mediated by gonadal and adrenal steroid hormones.
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PMID:Modification of pancreatic digestive function by pituitary grafting in mice. 765 48


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