“…The enzyme also has the ability to inactivate vasopressin and angiotensin II and so appears to have a broad specificity, hydrolysing aromatic neutral, basic and acidic N-terminal amino acids from the octapeptides (Tuppy, 1961; Ryden, 1966;Sjoholm & Yman, 1967;Mizutani et ai, 1979). It also splits the equivalent amide bonds in a number of synthetic peptides; the substrate behaviour of these peptides is similar to that of oxytocin (Tuppy, 1961; Ryden, 1966;Floyd et ai, 1973;Tovey et ai, 1973;Small & Watkins, 1974, 1975Mizutani et ai, 1979). The activity of oxytocinase which appears in the maternal circulation soon after conception and then increases progressively with gestational age is believed to be involved in both maintenance and termination of human pregnancy (Roy & Karim, 1983;Roy et ai, 1985aRoy et ai, , b, 1986aYeang, 1986).…”