IDENTIFICATION OF TRYPSIN-LIKE ACTIVITY IN STURGEON SPERMATOZOA

We documented amidase activity in lake sturgeon (Acipenser fulvescens) and white sturgeon (Acipenser transmontanus) spermatozoa. This activi ty was inhibited by benzamidine and soybean trypsin inhibitor (SBTI), and N-alpha-p-tosyl-L-lysine chloromethyl ketone-HCl (TLCK), but not b y N-tosyl-L-phenylalanine chloromethyl keton (TPCK), indicating the pr esence of trypsin-like activity in sturgeon spermatozoa. Higher activi ty occurred at pH 8.5 and 9.0 than at 8.0. No effect of 10 mM KCl and 100 mM NaCl on trypsin-like activity was found. Calcium ions inhibited the activity at 10 and 50 mM. Similar activities were documented in n eat semen and washed sperm suspension. Presence of trypsin-like activi ty corresponds to the presence of acrosomes and acrosome reaction in s permatozoa of these fishes. (C) 1994 Wiley-Liss, Inc.