[Localization and separation of various amino acid arylamidases in the uterus and blastocyst of the rabbit].

Distribution patterns of amino acid arylamidases have been studied in rabbit uterus and implantation stage blastocysts using a simultaneous coupling technique. A series of beta-naphthylamides (NAs) of various amino acids were used as substrates. Tests were performed at pH 6.5 and 7.5 using both Fast Blue B and Fast Garnet GBC as diazonium salts. Despite limited substrate specificity known in arylamidases, this procedure proved to be sufficient to give some evidence for the presence in uterus and blastocyst of at least three different arylamidases. NAs of aromatic amino acids (Phe, Tyr, Trp) are hydrolyzed predominantly by an enzyme showing maximum activity in uterine epithelium and in walls of blood vessels. An amino dicarbonic acid (alpha-Glu, alpha-Asp) NAs splitting arylamidase, possibly related to "aminopeptidase A", seems to be localized more specifically in myometrium and trophoblast. When NAs of basic (Arg, Lys) or certain other (Gly, Ala) amino acids were used, a strong reaction was obtained in myometrium, uterine epithelium, blood vessels and trophoblast as well. The observed patterns of distribution did not give evidence for the existence of an enzyme splitting exclusively Arg-betaNa and Lys-betaNA ("aminopeptidase B") although the activation by Cl- ions did. The problem of identification of different amino acid arylamidases by histochemical means will be discussed. For better localization, a section freeze substitution technique was found as efficient as the use of methoxy substrates. For the study of uterine secretion, either the section freeze substitution or the membrane method may be used.