[Determination of L-cystine aminopeptidase (serum oxytocinase, EC 3.4.1.2) during normal pregnancy].

It is given a method to the determination of cystine aminopeptidase activity in the serum in pregnancies. A time of few minutes is necessary for one determination. The determination is performed with a spectralphotometer or with the Reaction Rate Analyzer (LKB 8600) in using the chromogen substance 1-cystine-bis p-nitroanilide. This substance is solved in dimethylformamide. The normaly range of the 8th to the 41 th week of pregnancy is determinated in a number of 453. In twins the values were higher. The cystine aminopeptidase is nearly specifically in pregnancies and is produced in the plazenta. It is a statement of cellulary activity in the plazenta.