The correlation of three colorimetric oxytocinase determination methods used in clinics was compared and assessed. It was found that the new methods, the method of Kleiner and Brounet-Yager, and that of Usategui-Gomez et al., show a high correlation with respect to the Tuppy and Nesvadba method (modified by Klimek) the usefulness of which has already been proved. The method of Usategui-Gomez et al., using L-cystine-bis-p-nitroanilide as substrate, is more sensitive and has more advantages.
Aminopeptidases Colorimetry