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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors studied the dynamics of natural substrates of neurohumoral origin (oxytocin and lysine-vasopressin) by the serum of pregnant and nonpregnant women in relation to the pH in the medium, within pH limits of 2.5 to 8. The values obtained in a polarographic study of depression of the complex oxytocin and lysine-vasopressin polarographic wave by pregnancy and non-pregnancy sera and the results of a parallel analysis of free amino acids of the inactivated substrates under the same conditions showed that, apart from deep degradation of the studied substrates at the optimum pH (5.5 minus 8), less pronounced degradation of the molecule at low pH values (3 minus 4,5), i.e. in a non-physiological blood medium, also occurred. On the basis of their results, the authors submit the hypothesis of the existence of oxytocinase isoenzymes and of the probable presence of several peptidases with overlapping specificity.
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PMID:The influence of pH in the medium on degradation of neurohormones by pregnancy serum. 23 51

1 Synthetic analogues of oxytocin and of lysine-vasopressin with an hydroxyl group in either the L ro D configuration replacing the primary amino group have been tested for biological activity.2 [1-(L-2-Hydroxy-3-mercaptopropanoic acid)] oxytocin ([L-Hmp(1)]oxytocin) was 1.5 to 2 times more potent than oxytocin on the rat uterus in situ, the rat mammary strip and the rat mammary gland in situ and 3 times more potent on the rat isolated uterus.3 The pressor activity of [1-(L-2-hydroxy-3-mercaptopropanoic acid)-8-lysine]vasopressin ([L-Hmp(1), Lys(8)] vasopressin) was 2.2 and the antidiuretic activity 2.1 times that of lysine-vasopressin.4 The [D-Hmp(1)] analogues of oxytocin and vasopressin were much less potent than the [L-Hmp(1)] analogues.5 The responses to oxytocin and its hydroxy analogues in vivo were qualitatively indistinguishable but the pressor and antidiuretic responses to the hydroxy analogues of lysine-vasopressin were prolonged compared with those to the parent hormone.6 The hydroxy analogues of oxytocin and lysine-vasopressin were not inactivated by pregnancy plasma oxytocinase.7 The results are discussed in relation to the importance of the primary amino group for the biological activity and metabolism of the neurohypophysial hormones.
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PMID:Hydroxy analogues of oxytocin and of lysine-vasopressin. 51 8

1. Bothrops jararaca plasma or serum hydrolysed L-cystine-di-beta-naphthylamide (CNAse activity) at a degree comparable to that of plasma or serum in pregnant women. 2. In adult snakes, activity was less in males. It was not altered in pregnancy but increased after delivery, being higher at pH 6.4 (unspecific enzymes) than at pH 7.9 (true pregnant woman plasma oxytocinase). 3. Its optimum pH was 5.9, different from that of other known enzymes that hydrolyse the same substrate. 4. Bothrops jararaca plasma also hydrolysed vasopressin, oxytocin and vasotocin. 5. These hydrolysing activities were unexpected for an ovoviviparous reptile.
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PMID:Hydrolysis of L-cystine-di-beta-naphthylamide and neurohypophyseal peptides by the plasma of the snake Bothrops jararaca. 152 15

Human placental leucine aminopeptidase (P-LAP) was purified from retroplacental serum for the first time by serial chromatography on columns of Matrex Blue A, DEAE-Sepharose CL-6B, phenyl-Sepharose 4B, chelating-Sepharose, and Sepharose CL-6B. The purified P-LAP was apparently homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the apparent molecular weight (Mr) was estimated to be 210,000. By comparing P-LAP activity with cystine aminopeptidase activity, we concluded that both activities were shared by the same molecule. We also examined the hydrolytic activity of P-LAP using naturally occurring peptide hormones and found that the enzyme hydrolyzed oxytocin, vasopressin, and angiotensin III. These results suggest that P-LAP shows oxytocinase activity and plays an important role in the regulation of the plasma level of these hormones during pregnancy.
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PMID:Identification of human placental leucine aminopeptidase as oxytocinase. 173 8

This article, a review of factors controlling vasopressin (AVP) release in pregnancy, extends our contribution to a symposium in this journal published in 1987 (vol X, pp 270-275). Body tonicity decreases (approximately 10 mOsm/kg) very early in pregnancy due to decrements in the osmotic thresholds for AVP release and thirst. In addition, the metabolic clearance rate (MCR) of AVP markedly increases between gestational week 10 and midpregnancy, and is paralleled by the appearance and increase of circulating cystine aminopeptidase (vasopressinase), while the MCR of 1-deamino-8-D-AVP (DDAVP), an analogue resistant to inactivation by the enzyme, changes little in pregnancy. These increases (MCR of AVP and plasma vasopressinase) may explain certain syndromes of transient diabetes insipidus (DI) that complicate gestation. Finally, mechanisms responsible for the altered osmoregulation in pregnancy are obscure, but chorionic gonadotropin may be involved in the changes during human gestation.
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PMID:Osmotic and volume control of vasopressin release in pregnancy. 199 49

Aminopeptidase from dysgerminoma was purified and characterized using L-leucine-beta-naphthylamide as substrate. The enzyme was resistant to puromycin, methionine, amastatin, bastatin, and EDTA, and it was heat labile at 60 degrees C. The enzyme showed the same electrophoretic mobility as pregnant-patient serum oxytocinase CAP1 on polyacrylamide gel electrophoresis. Km value against S-benzylcysteine-p-nitroanilide was 4.2 X 10(-4) M. Oxytocin and vasopressin competitively inhibited the enzyme activity. Molecular weight of the enzyme was estimated to be 80,000 by Sephadex G-200 column chromatography. These results suggest that aminopeptidase from dysgerminoma is an oxytocinase-like enzyme, a placenta-specific protein.
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PMID:Oxytocinase-like enzyme in an ovarian dysgerminoma: a placenta-specific protein. 408 42

This review stresses changes in osmoregulation as well as the secretion and metabolism of arginine vasopressin during pregnancy, focusing on human gestation. Pregnant women experience a decrease in body tonicity, plasma osmolality decreasing immediately after conception to a nadir approximately 10 mosmol/kg below non-pregnant levels early in pregnancy, after which a new steady state is maintained until term. Data from both human and rodent gestation have led to a formation of how these changes occur. The osmotic thresholds for thirst and antidiuretic hormone release decrease in parallel. Lowering the threshold to drink stimulates increased water intake and dilution of body fluids. Because arginine vasopressin (AVP) release is not suppressed at the usual level of body tonicity, the hormone continues to circulate and the ingested water is retained. Plasma osmolality declines until it is below the osmotic thirst threshold, and a new steady state with little change in water turnover is established. Pregnancy is characterized by increments in intravascular volume, but volume-sensing AVP release mechanisms appear to adjust as gestation progresses so that each new volume status is "sensed" as normal. The metabolic clearance of AVP increases fourfold, the rise paralleling that of circulating cystine aminopeptidase (vasopressinase), and enzyme produced by the placenta. Furthermore, the disposal rate of 1-deamino-8-D-AVP, and AVP analogue resistant to inactivation by vasopressinase, is unaltered in pregnancy. Thus, the increase in AVP's metabolism and the high circulating aminopeptidase levels have been implicated in certain forms of transient diabetes insipidus that occur in late pregnancy. Finally, mechanisms responsible for the altered osmoregulation in pregnancy are obscure, but chorionic gonadotropin and relaxin may be implicated in the changes.
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PMID:Osmoregulation, the secretion of arginine vasopressin and its metabolism during pregnancy. 785 29

An aminopeptidase from porcine kidney, hydrolyzing oxytocin and vasopressin in vitro, was purified by chromatography on hydroxyapatite, DEAE-cellulose and nickel ion chelate gel and gel filtration on Sephadex G-100. The enzyme appeared to be a high molecular mass (M(r) 105,000) monomeric protein. It was sensitive to inhibition by metal chelator, o-phenanthroline. Cobalt ion and sulfhydryl activator, 2-mercaptoethanol, had activating effects, while p-chloromercuribenzoate, amino acids with large hydrophobic side chains, L-cystine and aminopeptidase inhibitors, bestatin and amastatin, had inhibitory effects on the enzyme activity. The enzyme hydrolyzed several aminoacyl p-nitroanilides, and had the highest specificity against S-benzyl-L-cysteine p-nitroanilide. The properties of the enzyme were distinct from those of well-characterized leucyl aminopeptidase (EC 3.4.11.1), membrane alanyl aminopeptidase (EC 3.4.11.2) and primate placental cystinyl aminopeptidase (EC 3.4.11.3).
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PMID:An aminopeptidase activity from porcine kidney that hydrolyzes oxytocin and vasopressin: purification and partial characterization. 787 63

Oxytocinase (EC 3.4.11.3) activity was determined in 80 amniotic fluid samples obtained from 40 normotensive primigravidas (median age 27 years) and 40 primigravidas (median age 29 years) with pregnancies complicated by preeclampsia between 32 and 39 weeks of gestation. The enzyme activity was significantly lower in preeclampsia than in normal pregnancy with matched gestations (p < 0.01). Considering the possible involvement of vasopressin and angiotensin II in preeclampsia, it is suggested that the enzyme which degrades these pressor hormones may play a role in the pathogenesis of hypertensive pregnancy.
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PMID:Decreased levels of amniotic fluid oxytocinase activity in preeclampsia. 850 9

We describe a case of diabetes insipidus (DI) due to a pituitary tumor in a 33-year-old pregnant woman who developed a sudden onset of polyuria (over 8 l/day) and polydipsia at 30 weeks of gestation. Her plasma concentration of vasopressin (AVP) was low compared with high serum osmolality (298 mOsm/kg), and her urine output was well controlled by treatment with desmopressin acetate (DDAVP). Cranial magnetic resonance imaging (MRI) demonstrated a 1.8 x 1.2-cm pituitary tumor, but she did not have any disturbance in the release of anterior pituitary hormones. The serum concentration of cystine aminopeptidase (CAP) was within the normal range for a woman at 34 weeks of gestation. After an uncomplicated delivery of a healthy girl, her polyuria gradually resolved. The size of the pituitary tumor gradually decreased in parallel to a reduction in her urine output, but a silent hemorrhage was detected in her pituitary gland 4 weeks after the delivery. Although pregnancy is sometimes associated with central DI, the occurrence of DI due to pituitary tumor under pregnancy is rare. The basal AVP recovered to within the normal range, but the low response of AVP secretion to high osmolality persisted. In this case, pregnancy may affect the manifestation of subclinical DI. This case may therefore enhance our understanding of the mechanisms of DI during pregnancy.
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PMID:Manifestation of subclinical diabetes insipidus due to pituitary tumor during pregnancy. 898 Sep


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