Seminal plasma proteins of Atlantic halibut (Hippoglossus hippoglossus L.).

Protein content and properties in the seminal plasma of Atlantic halibut (Hippoglossus hippoglossus) were assayed using spectrophotometric and electrophoretic methods. The protein concentration ranged from 6.4 +/- 3.1 to 19.4 +/- 3.4 mg ml(-1) and anti-proteolytic activity from 585.2 +/- 104.6 to 2912.4 +/- 367.4 U l(-l). A high correlation between anti-proteolytic activity and protein concentration (r = 0.95), and between sperm concentration and osmolality was found (r = 0.92). There was a significant decrease in anti-proteolytic activity from the first to the second sampling, but not in protein concentration. Anti-proteolytic activity and protein concentration were significantly affected by variations in individual males. Electrophoresis revealed four anti-proteolytic bands and individual differences in bands of proteolytic activity, which were subsequently characterized as metalloproteases and serine proteases.