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

TRH and pseudo-hormone (pyro Glu-His-amphetamine) were submitted to the digestion of chymotrypsin and prolidase and independently to the digestion of enzymes of the digestive track: pepsin (stomach), pancreatins (pancreas) and enzymes extracted from the intestinal mucosa (small intestine). Using thin layer chromatography and high voltage electrophoresis techniques to detect enzymic digestion products, only intact TRH and pseudo-hormone were found, indicating that both entities were, under the conditions used, resistant to in vitro digestion by enzymes of the digestive tract.
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PMID:Evidence for the resistance of thyrotropin-releasing hormone (TRH) and pseudo-hormone, pyroglutamyl histidyl-amphetamine, to degradation by enzymes of the digestive tract in vitro. 11 43

We previously reported that the rat posterior pituitary contains a potent PRL-releasing factor (PRF) which is distinct from oxytocin (OT), TRH, and angiotensin II (AII). The objectives of this study were 1) to examine whether posterior pituitary extracts stimulate PRL release in the presence of dopamine (DA), 2) to determine the chemical nature of PRF, and 3) to estimate its mol wt. Perifused anterior pituitary cells were used to assess PRF activity. Posterior pituitaries and medial basal hypothalamus (MBH) fragments were extracted with perchloric acid and lyophilized. Subsequent to various treatments, samples were reconstituted in the perifusion medium and introduced to the cells in short pulses. Fractions were collected and analyzed for hormone content by RIA. During a constant infusion of DA (50 nM), PRL secretion was inhibited by 75%, yet the posterior pituitary extract retained its ability to rapidly stimulate PRL release. Studies using proteolytic enzymes showed that posterior pituitary PRF was resistant to inactivation by trypsin, whereas the PRF activity of AII was abolished. Both chymotrypsin and proline-specific endopeptidase significantly reduced the PRF activity in the posterior pituitary. The PRL-releasing activity of TRH was not affected by chymotrypsin. Immunoreactive vasoactive intestinal polypeptide was undetectable in posterior pituitary extracts. Oxidation of posterior pituitary extracts with performic acid caused only a modest reduction of their PRF activity, while the ability of OT to stimulate PRL release as well as immunoreactive OT was abolished. Studies using ultrafiltration membranes showed that the PRF activity in the posterior pituitary was less than 5,000 mol wt. Furthermore, posterior pituitary PRF partitioned in nearly equal amounts across 1K membranes, as did AII and OT. In contrast, about 80% of the PRF activity in the MBH and all of the synthetic TRH passed through the 1K membranes. We conclude that 1) posterior pituitary PRF can stimulate PRL secretion from perifused anterior pituitary cells in the presence of physiological concentrations of DA; 2) PRF is a small peptide(s) of less than 5,000, and perhaps closer to 1,000, mol wt; 3) PRF is resistant to inactivation by trypsin and to oxidation by performic acid, but is hydrolyzed by both chymotrypsin and proline-specific endopeptidase; and 4) these data further distinguish posterior pituitary PRF from known PRL secretagogues.
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PMID:Characterization of prolactin-releasing factor in the rat posterior pituitary. 313 Nov 18

Recent studies have shown that thyrotropin-releasing hormone is present in gastrointestinal tissues and has effects on gastrointestinal motility and secretion. In the present study, we have investigated in healthy subjects the effects of various doses of thyrotropin-releasing hormone on secretin-cholecystokinin-stimulated pancreatic secretion. Intravenous infusion of thyrotropin-releasing hormone at doses of 4, 20, and 100 microgram/30 min, administered during a constant pancreatic stimulation with secretin (0.5 Clinical Units/kg/h) and cholecystokinin (0.5 Ivy dog units/kg/h), produced a significant decrease in lipase and chymotrypsin secretion without affecting volume and bicarbonate secretion. The decrease appeared immediately with the lowest dose of TRH employed, and was progressively more marked with increasing doses of the hormone. Compared with the control experiments, the maximal inhibition of lipase output reached -17.6%, -37.2%, and -43%, and the maximal inhibition of chymotrypsin output -18.2%, -39.3%, and -44.9%, for the three doses of thyrotropin-releasing hormone employed, respectively. It is concluded that TRH has a marked inhibitory effect on the enzymatic component of the pancreatic secretion stimulated by submaximal doses of secretin and cholecystokinin. The physiologic importance of this effect remains to be defined.
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PMID:Thyrotropin-releasing hormone inhibits pancreatic enzyme secretion in humans. 678 73