The Comparative Study of Myofibrillar Proteins of Skeletal Muscles of Some Deep-Sea Fish Species

Comparative characteristics, common and distinctive features of qualitative and quantitative composition of myofibril proteins of skeletal muscles of some deep-sea fish species (Podonema longipes, Coryphaenoides cinereus, Coryphaenoides pectoralis) have been determined. Myofibrillar proteins were extracted from the skeletal muscle of three species deep-sea fish and their relative molecular mass was estimated by SDS/polyacrylamide gel electrophoresis. Subunit and quantitative compositions of deep-sea fish proteins were determined. The molecular weight of predominant contractile proteins, myosin (with heavy chains and two light chains), actin, troponin and tropomyosin was about 492, 47, 38 and 35 kDa, respectively for all fish species. The myosin/actin ratios were determined to be 2.85, 2.76 and 2.56 respectively for C. cinereus, P. longipes, and C. pectoralis. The Ca2+-ATPase activity of C. cinereus and P. longipes actomyosins was significantly higher at low ionic strengths (0.317 and 0.324 μМ Pi mg -1min-1 accordingly) than at high ionic strengths (0.257 and 0.221 μМ Pi mg -1min-1 accordingly). At the same time the Mg2+ATPase activity value remained almost constant at both high and low ionic strengths (0.169–0.178 μМ Pimg -1min-1). The Ca2+-ATPase activity of C. cinereus, P. longipes and C. pectoralis myosins was 0.534, 0.641 and 0.376 μМ Pi mg -1min-1 respectively.