inactivation of Pineal Antigonadotrophin by Proteolytic Enzymes

There is evidence that substances possessing higher molecular weights than the pineal indole derivatives may be responsible for the antigonadotrophic activity of pineal extracts (Cheesman & Fariss, 1970; Moszkowska, Kordon & Ebels, 1971; Benson, Matthews & Rodin, 1972). This possibility is suggested first by the fact that pineal extracts are more active than the melatonin which they contain (Benson, Matthews & Rodin, 1971), and secondly by the discovery that the activity of pineal extracts can be separated from the melatonin using Sephadex G-10 and G-25 (Ebels, 1967; Benson et al. 1972). The non-melatonin pineal activity, referred to as pineal antigonadotrophic factor (PAG), was retained in the 500\p=n-\1000 molecular weight fraction after ultrafiltration on Diaflo membranes and was found in a ninhydrin-positive peak when chromatographed on Sephadex G-25 (Benson et al. 1972). Con-sidering that these studies were performed with defatted bovine pineal powder, one would suspect that the active substance is probably a polypeptide or small glyco-peptide (Benson, Matthews & Smith, 1973). Polypeptides structurally similar to oxytocin and vasopressin have also bee