Open AccessHormonal Interactions at the Molecular Level
Author(s) -
Camier Maryse,
ALAZARD Robert,
Cohen Paul,
PRADELLES Philippe,
Morgat JeanLouis,
FROMAGEOT Pierre
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb02598.x
Subject(s) - neurophysins , oxytocin , vasopressin , vasotocin , lysine , chemistry , peptide , peptide hormone , biochemistry , hormone , endocrinology , medicine , biology , neuropeptide , amino acid , receptor
Bovine neurophysins I and II have been obtained in a highly purified state using isoelectric focusing. The interactions of oxytocin and [8‐lysine]vasopressin with these proteins have been investigated by thin‐film equilibrium dialysis using highly radioactive hormones retaining their full biological activities.1 Binding of both oxytocin and [8‐lysine]vasopressin to neurophysins I and II as a function of pH leads to typical “bell‐shaped” curves. The patterns obtained indicate functional differences in the binding of oxytocin to neurophysin I compared with neurophysin II. No significant change was detected in the case of [8‐lysine]vasopressin. 2 Scatchard plots indicate that both hormones bind neurophysins I and II with similar affinities. They demonstrate that at pH 5.7 one oxytocin molecule and two [8‐lysine]vasopressin molecules can be bound per neurophysin I or II monomer. 3 Ca 2+ and Mg 2+ had no effect on the binding process of either [8‐lysine]vasopressin or oxytocin. Iodination on the tyrosyl ring of [8‐lysine]vasopressin and oxytocin resulted in the suppression of their binding ability. 4 Competition experiments between oxytocin and vasopressin show that each compound inhibits the binding of the other peptide in a non‐competitive fashion.