Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

[1-Penicillamine,2-leucine]oxytocin was synthesized by the solid-phase method of peptide synthesis and purified by partition chromatography on Sephadex G-25, followed by gel filtration. The peptide was found to be a very potent competitive inhibitor of oxytocin in the oxytocic assay with a pA2 of 7.14 and an inhibitor of oxytocin in the milk-ejecting assay. The compound showed no agonist activity in either of these assays, and its inhibitory activity at the uterus was of prolonged duration. The 13C nuclear magnetic resonance spectral properties and the 13C T1 (spin-lattice) relaxation times of [Pen1,Leu2]oxytocin were determined, and the results were compared with previous studies of [Pen1]oxytocin, a related competitive inhibitor, and oxytocin, the native hormone agonist. These studies indicated that the hormone inhibitors [Pen1,Leu2]oxytocin and [Pen1]oxytocin have similar conformational and dynamic properties which are different than those of the agonist, oxytocin.
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PMID:[1-Penicillamine,2-leucine]oxytocin. Synthesis and pharmacological and conformational studies of a potent peptide hormone inhibitor. 42 85

The solid phase syntheses of [2-cycloleucine] oxytocin and [1-penicillamine, 2-cycloleucine] oxytocin are reported. [1-Penicillamine, 2-cycloleucine] oxytocin is an oxytocin antagonist exhibiting no in vitro oxytocic activity. In the in vitro oxytocic assay, [1-penicillamine, 2-cycloleucine] oxytocin has a pA2 value of 6.70 +/- 0.08. [2-Cycloleucine]-oxytocin is a full oxytocin agonist exhibiting 4.9 +/- 0.5 U/mg of oxytocic activity. Neither compound possesses any measurable agonist or antagonist activity in the rat pressor assay. Carbon-13 nuclear magnetic resonance chemical shift parameters and spin-lattice relaxation times (T1) of the antagonist, [1-penicillamine, 2-cycloleucine] oxytocin, indicate that the antagonist exhibits similar conformational and dynamic properties as other oxytocin inhibitors previously studied. The carbon-13 nuclear magnetic resonance shift parameters and spin-lattice relaxation times (T1) of the oxytocin agonist, [2-cycloleucine] oxytocin, indicate that the agonist exhibits similar conformational and dynamic properties as oxytocin. These results are discussed in terms of the different receptor requirements for agonist and antagonist activities. It appears that there are different structural and conformational requirements at the 2-position for oxytocic agonist and antagonist activities.
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PMID:Pharmacological, conformational and dynamic properties of cycloleucine-2 analogues of oxytocin and [1-penicillamine]oxytocin. 682 79

The solid phase synthesis of [1-penicillamine, 4-threonine]-oxytocin and [1-penicillamine, 2-phenylalanine, 4-threonine]-oxytocin is reported. The two compounds have no in vitro milk ejecting activity and no in vivo or in vitro oxytocic activity, but both are potent antagonists in these three assay systems. In the in vitro oxytocic assay, [1-penicillamine, 4-threonine]- and [1-penicillamine, 2-phenylalanine, 4-threonine]-oxytocin have pA2 values of 7.55 +/- 0.04 and 7.67 +/- 0.02, respectively, and both inhibit the uterine contractile response to oxytocin in nonpregnant and pregnant rats. [1-Penicillamine, 2-phenylalanine, 4-threonine]-oxytocin has a weak antipressor activity and at high doses, consistently caused a weak and transient fall in blood pressure in the rat. Carbon-13 nuclear magnetic resonance chemical shift parameters and spin-lattice relaxation times (T1) indicate that these two new oxytocin antagonists have very similar conformation and dynamic properties to oxytocin inhibitors which have previously been examined. These results are discussed in terms of conformational and dynamic models of oxytocin antagonism at the uterus. It is suggested that conformational restrictions at the 2- and 4-positions of penicillamine-1 analogues of oxytocin are important to antagonist activity and potency.
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PMID:Synthesis, pharmacological, conformational, and dynamic studies of the potent hormone antagonists [1-penicillamine, 4-threonine]-oxytocin and [1-penicillamine, 2-phenylalanine, 4-threonine]-oxytocin. Conformational and dynamic considerations in the design of antagonists. 721 13

[1-Penicillamine,2-leucine]oxytocin is a conformationally restricted analogue of oxytoxin in which the half-cystine-1 and tyrosine-2 residues of the native hormone are replaced by half-penicillamine (beta, beta-dimethyl-half-cystine) and leucine, respectively. This analogue is a surprisingly potent oxytocin antagonist [Hruby, V. J., Deb, K. K., Yamamoto, D. M., Hadley, M. E., & Chan, W. Y. (1979) J. Med. Chem. 22,7]. Extensive proton magnetic resonance experiments were performed to determine the conformational properties of this analogue in aqueous solution, and the results were compared with the previously published model for the conformation of [1-penicillamine]oxytocin. The results are consistent with a conformation similar to that of [1-penicillamine]oxytocin except that, while [1-penicillamine]oxytocin in aqueous solution possesses two 1 comes from 3 (C7) type turns involving the isoleucine-3 peptide amide proton and the half-penicillamine-1 carbonyl and the asparagine-5 peptide amide proton and the isoleucine-3 carbonyl, [1-penicillamine,2-leucine)oxytocin has only the latter 1 comes from 3 turn. This difference between the antagonists is reflected in the different phi and psi angles in the three N-terminal residues of the two inhibitor analogues and in differences in the preferred side-chain conformations for several residues. One particular result of these conformational differences is that, whereas for [1-penicillamine]oxytocin the tyrosine-2 side chain is unable to assume the rotamer for maximal binding to the uterine receptor, [1-penicillamine,2-leucine]oxytoxin retains conformational and dynamic properties at residues two and three which are more similar to those of oxytocin. It is postulated that these conformational and dynamic properties are consistent with the stronger binding and, hence, greater antagonist activity for this penicillamine analogue relative to [1-penicillamine]oxytocin.
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PMID:Conformational study of the potent peptide hormone antagonist [1-penicillamine,2-leucine]oxytocin in aqueous solution. 724 50