Human seminal fluid was fractionated using a column of Sephadex 100 and 200 and the enzymic activity of the fractions was tested using several aminoacid naphthylamides as substrate. Only one protein peak showed activity and hydrolyzed the naphthylamides in the following order: Ala ~ Meth ~ Leu His ~ Arg ~ Lys, etc. Naphthylamides of N~-substituted arginine or of proline and hydroxyproline were not hydrolyzed at all. Assays using combined substrates demonstrated the presence of only one aminopeptidase in the fractions tested. The aminopeptidase was dependent on Fe2+-ions. No indication on the presence of aminopeptidase A or B could be found.
Zusammen]assung. Menschliche Samenfliissigkeit wurde unter
Benutzung einer Sanle aus Sephadex 100 und 200 fraktioniert und die enzymatische Aktivitat der Fraktionen getestet bei Benutzung yon verschiedenen aminosauren Naphthylamiden als Substrat. Nut ein Protein-Maximum zeigte Aktivitat und hydrolysierte die Iqaphthylamide in der folgenden Reihenfolge: Ala ~ ~eth ~ Leu ~ His ~ Arg Lys, usw. Naphthylamide yon N~-substituiert~m Arginin oder yon Prolin und Itydroxyprolin warden iiberhaupt nicht hydrolysiert. Untersuchungen mit kombinierten Substraten zeigten die Anwesenheit yon nut einer Aminopeptidase in den getesteten Fraktionen. Die Aminopeptidase war abhangig yon FeU+-Ionen. Fiir die Anwesenheit yon Aminopeptidase A oder B konnten keine Anzeichen gefunden werden.
The presence of an a m i n o p e p t i d a s e in the h u m a n seminal fluid was first described b y LUNDQUIST et al. (1955). The p r e p a r a t i o n purified a b o u t 10 times was found to hydrolyze a n u m b e r of di-and t r i . p e p t i d e s and to have no preference to leucylpepticles. L a t e r it has been shown t h a t also leueyl-fi-naphthylamide is h y d r o l y z e d v e r y fast b y the seminal fluid ( K ~w r x T z and DOV. Pr~ER, 1961) and this hydrolysis as well as the hydrolysis of a l a n y l a n d glyeyl-fi-naphthylamide has been ascribed to the same active enzyme h y d r o l y z i n g also di-and tri-peptides (WIENEKE and DOEPFMEI~, 1965). This conclusion was based on the fact t h a t efforts to separate the enzymic activities capable of hydrolyzing these s u b s t r a t e s using DEAE-celhilose c h r o m a t o g r a p h y were not successful. The s t a t e m e n t was further s u p p o r t e d b y findings m a d e using various modifier substances and b y experiments with "combined substrates.