In vitro biosynthesis of rabbit blastokinin.

The authors have incubated, in vitro, estrous rabbit endometrium with 3H-leucine and pseudopregnant rabbit endometrium with 14C-leucine. By the double-labeling technique and the use of the 14C:3H ratio, it was shown that blastokinin (BKN) is neosynthesized in vitro and that this neosynthesis probably also affects other protein components. By ion exchange chromatography of the supernatant of the pseudopregnant endometrium and previously purified BKN, it was possible to confirm the in vitro biosynthesis and to exclude interfering phenomena. Time dynamics showed that biosynthesis was more marked between the 18th and 24th hours of incubation.