Figure 5.

Analysis of sperm extracts after affinity chromatography (benzamidine sepharose). (a) Electrophoretic profiles of fractions collected after affinity chromatography on sperm extracts. Black arrows indicate the more abundant proteins, * indicates the active form of the acrosin. (b) Amidase activities. Two hundred nanograms of proteins from each fraction were incubated in presence of BAPNA in a 50 mM Tris‐HCl buffer, pH 8.0 at 37°C for 20 min. AU, absorbance unit at 410 nm. (c) Effect of SPINK2 on serine protease activity of F3 fraction (■) and F4 fraction (○). Two hundred nanograms of proteins from F3–F4 fractions were incubated with increasing amounts (0–800 nM) of purified SPINK2 in a 50 mM Tris‐HCl buffer, pH 8.0 at 37°C for 20 min. The percentage of remaining sperm protease activity is indicated in y‐axis and inhibitor concentration (nM) is indicated in x‐axis. RE: row extract; UN: unbound fraction; F1‐F10: eluted fractions