Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Melanin concentrating hormone (MCH) is a heptadecapeptide isolated from chum salmon (Oncorhynchus keta) pituitaries. The peptide has been isolated from whole brain extract at a low yield of 1.2 micrograms/1300 brains. MCH activity in the hypothalamus was characterised by in vitro scale bioassay and radioimmunoassay. Specificity of these assay systems was examined with neurotransmitters such as epinephrine, norepinephrine, and dopamine, hypothalamic hormones such as somatostatin, isotocin, Arg-vasotocin, oxytocin, and Arg-vasopressin, and salmon prolactin and its chymotryptic peptide or salmon PRL176-187. Among them only salmon PRL176-187 exhibited weak activities in both assays. The neurotransmitters were 10(4) to 10(5) times less potent than MCH in the bioassay. MCH concentrations in a pituitary and a hypothalamus were estimated as 5300 +/- 750 ng (ca. 106 micrograms/g) and 48 +/- 9.5 ng (ca. 1.6 micrograms/g), respectively, by radioimmunoassay. Lysyl endopeptidase digestion of the hypothalamic extract resulted in a significant increase of biological activity as well as of immunoreactivity. Gel filtration of the hypothalamic extract and subsequent enzymatic digestion revealed that the fractions at higher molecular weight were contributory to the increase in the activities.
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PMID:Characterization of melanin concentrating hormone in teleost hypothalamus. 288 42

1. In vivo the effects of endothelin-1 (ET-1) are limited by its rapid removal from the circulation and possibly by its metabolism by enzymes such as neutral endopeptidase 24.11, deamidase or carboxypeptidase A. Here, using as a model the isolated perfused mesenteric arterial bed of the rat, we have examined the involvements of these enzymatic activities in the vascular responses to ET-1. 2. Samples of Krebs buffer which had been recirculated through the mesenteric arterial bed for 30 min rapidly destroyed the activity of ET-1 as assessed either by bioassay on rings of rat thoracic aorta or by high performance liquid chromatography (h.p.l.c.). For instance, after 15 min incubation with the recirculated-Krebs solution (recirc-K) the contraction induced by 3 x 10(-9) M ET-1 was reduced by more than 90%. Contractions induced by sarafotoxin 6b (3 x 10(-9) M) were similarly suppressed by preincubation with recirc-K whereas those to Arg-vasopressin (3 x 10(-9) M) were unaffected. 3. The degradation of ET-1 by recirc-K was prevented by 1,10-phenanthroline (10(-3) M), abolished by heating the recirc-K solution to 90 degrees C for 15 min, and reduced by EGTA (5 x 10(-3) M) or ET-1(16-21) (10(-5) M). For instance, in the presence of ET-1(16-21) (n = 6) the contraction induced by ET-1 was reduced by only 40% after 15 min incubation with recirc-K buffer. Leupeptin (3 x 10-4 M), dichloroisocoumarin(5 x 10-5 M), phenylmethyl-sulphonyl fluoride (10-3 M), a combination of bacitracin (300 mg ml-1),bestatin (10-5 M), captopril (10-5 M), phosphoramidon (10-4 M) and thiorphan (10-4 M) or Polypep (aproprietary protein digest) did not inhibit the degradation of ET-1 by recirc-K.4. In experiments examining directly the vascular responses of the isolated perfused mesentery of the rat, the addition of cumulative concentrations of ET-1 to the recirculating Krebs solution caused small concentration-dependent increases in perfusion pressure. The inclusion of ET-1(16-2l), ET-1(17-21), or ET-1(18-21) (10-5M) greatly potentiated these responses, but not those to Arg-vasopressin or methoxamine.The effects of 1,10-phenanthroline or EGTA could not be examined in this system because these agents both depressed non-specifically the vasoconstrictor responses of the mesenteric vascular bed.5. Thus, the rat mesentery releases an enzyme that very rapidly destroys ET-1 or the very closely related peptide, sarafotoxin 6b but not Arg-vasopressin. This enzyme is most probably a metallopeptidase because of its sensitivity to inhibition by 1,10-phenanthroline or EGTA. It is particularly interesting that a simple vascular bed such as the mesentery produces such a powerful endothelin metabolising enzyme. It is tempting, therefore, to speculate that the endothelin degrading enzyme active at neutral pH that- we have found is important in the metabolism of ET-1 throughout the vasculature.
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PMID:Rapid degradation of endothelin-1 by an enzyme released by the rat isolated perfused mesentery. 777 48