Induction of gelatinolytic activities in ayu muscle at the spawning stage

Gelatinolytic activities derived from both serine proteinase and metalloproteinase were induced in mature ayu muscle. These activities from ayu muscle at spawning stage (November) were fractionated successively by DEAE-cellulose, CM-cellulose, and gelatin affinity chromatographies, while no corresponding activity was detected from that of the growing stage (July). A gelatinolytic active band adsorbed to a CM-cellulose column was detected at 80 kDa by gelatin zymographic analysis. The activity was expressed at a slightly alkaline pH range and optimally at pH 8.5. The activity was inhibited by leupeptin and 1,10-phenanthroline, but not by E-64, suggesting that it was composed of both serine proteinase and metalloproteinase. Serine-type activity at 80 kDa was not adsorbed to a gelatin-immobilized column. On the other hand, metallo-type activity was adsorbed to the column, and the molecular mass of the activity was estimated to be 68 kDa. Our findings suggested that these gelatinolytic activities due to both serine proteinase and metalloproteinase, which are specifically induced in the spawning stage, are possibly responsible for collagen breakdown according to maturation.