title: The influence of pH in the medium on degradation of neurohormones by pregnancy serum.
abstract: 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.
mesh_terms: D000596:Amino Acids / Q000097:blood; D001711:Biotransformation; D003470:Culture Media; D010122:Cystinyl Aminopeptidase; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000097:blood; D008236:Lypressin / Q000097:blood; D010121:Oxytocin / Q000097:blood*; D011048:Polarography; D011247:Pregnancy; D014667:Vasopressins / Q000031:analogs & derivatives*
chemical_list: D000596:Amino Acids; D003470:Culture Media; D007527:Isoenzymes; D014667:Vasopressins; D010121:Oxytocin; D008236:Lypressin; D010122:Cystinyl Aminopeptidase