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Human placental oxytocinase and its relationship to pregnancy plasma oxytocinase

par Kleiner, Henri ;Vermeulen, Claudine ;May, Claude ;Yager, Michèle ;Popowski, Anna;Mosselmans, Roger ;Graff, Guy
Référence Clinica chimica acta, 101, 1, page (113-123)
Publication Publié, 1980-02

Article révisé par les pairs

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Résumé :

Plasma "oxytocinase of pregnancy" and three placental "oxytocinase" fractions from human placental extracts were compared. On the basis of acrylamide-agarose chromatography, polyacrylamide gel electrophoresis, substrate specificity, heat lability and relative in sensitiveness to L-methionine, it is concluded that placental enzyme activities, present in the second acrylamide-agarose peak, are identical with the plasma "pregnancy oxytocinase" and are to be regarded as its source. The hypothesis of a transplacental passage of placental peak II oxytocinase in the blood compartment of the mother seems well supported. Heat treatment of the placental extracts uncovered a minor activity behaving like Oya's microsomal oxytocinase, which is totally unlike the plasma oxytocinase and plays no part in the increased oxytocinase activity of human pregnancy plasma. A hitherto undescribed enzyme activity shares with the pregnancy oxytocinase its specificity towards l-leucyl-β-naphthylamide and di-s-s-l-cysteinylβ-naphthylamide, its heat lability and relative insensitiveness to l-methionine. However, this activity is carried by a protein of much lower molecular weight as judged by acrylamide-agarose chromatography, which shows only a single activity band on polyacrylamide gel electrophoresis. © 1980.