Evidence for a Proteinase Inhibitor Binding Component Associated with Murine Spermatozoa 1

Abstract

The supernatants of frozen-thawed murine epididymal sperm suspensions contain a heat-labile component capable of binding a low molecular weight, acid-stable proteinase inhibitor of seminal vesicle origin. The substance has a molecular weight of approximately 15,000 and can be isolated by affinity chromatography using the inhibitor as the ligand. Although the substance has no inherent enzymatic properties, it will decrease the activity of the seminal inhibitor in the standard N-benzoyl-DL-arginine-p-nitroanilide (BAPNA) assay. Enzyme-linked immunosorbent assays (ELISA) indicate that the substance, when bound to microtiter plates, is capable of binding the seminal vesicle inhibitor. Turkey egg white trypsin inhibitor will decrease the amount of the seminal inhibitor that will bind to the substance, while noninhibitor proteins, e.g., bovine serum albumin or insulin, have no effect. Turkey egg white and lima bean trypsin inhibitor will also decrease the amount of seminal vesicle inhibitor capable of binding to washed sperm. These data indicate the presence of an inhibitor acceptor site associated with murine epididymal spermatozoa.

Developmental Profile of a Caltrin-Like Protease Inhibitor, P12, in Mouse Seminal Vesicle and Characterization of Its Binding Sites on Sperm Surface1

“…Since proacrosin is not exposed on the sperm surface but is located in the acrosomal matrix of intact sperm [33], P12 is unlikely to interact with the zymogen unless P12 penetrates into the acrosomal region. In fact, there is one protein component, which is distinct from acrosin/proacrosin but is capable of binding a PI of seminal vesicle origin, in the supernatant of frozen-thawed murine epididymal sperm suspension [34].…”

Binding of a murine proteinase inhibitor to the acrosome region of the human sperm head

“…The molecular weight of the component from the human sperm extract that binds murine SVI is -20,000. This is larger than the comparable component (15,000) found on murine sperm (Aarons et al, 1984). In the mouse the inhibitor binding component functions in zona binding (Poirier et al, 1986) and is the approximate size of the murine zona binding components (16,000-19,000) found by O'Rand et al (1985).…”

“…Treating sperm with purified SVI blocks sperm-zona binding (Poirier et al, 1986). The inhibitor binding site, the acceptor, is heat labile and has a molecular weight of 15,000 (Aarons et al, 1984). Treating oocytes with purified acceptor reduces in a concentration-dependent manner the number of sperm able to bind (Poirier et al, 1986).…”

From Catalysts to Bioactive Organometallics: Do Grubbs Catalysts Trigger Biological Effects?

“…The enzymatic activities were determined afterwards according to established procedures and expressed as EC 50 values (Table 1). [15][16][17] Whereas for GR and trypsin no inhibition was observed up to 100 mm, for TrxR and catB in most cases a noticeable inhibition of the enzymatic activity was observed with the order of activity G1 < G2 < HG1 < HG2. Comparing the structures of the complexes, the results of the enzyme inhibition assays overall indicate a positive influence of the isopropyloxo group and NHC ligand.…”