ティラピア背筋ミオシンの精製およびその性質について

抄録

Myosin from dorsal muscle of tilapia, Tilapia mossambica, was purified by chromatography on DEAE-Sephadex A-50. Its properties have been investigated.
1. The ratio of the absorption of tilapia myosin at 280mμ to that at 260mμ was 1.83. The purity of this protein was examined by analytical ultracentrifugation, rechromatography on DEAE-Sephadex A-50 and SDS-polyacrylamide gel electrophoresis.
2. The intrinsic viscosity ([μ]=2.15dl/g) and the sedimentation coefficient (S⁰_{20, w}=6.38S) of tilapia myosin were very similar to those of rabbit myosin, respectively.
3. The amino acid composition of tilapia myosin was generally similar to that of rabbit myosin. The apparent specific volume of tilapia myosin calculated from the amino acid composition was 0.734cm³/g.
4. Its biological activities such as ATPase properties and combining ability with actin was fundamentally the same as those of rabbit myosin. The Ca²⁺-ATPase activity of tilapia myosin was more stable than that of carp myosin.
These results indicated that our tilapia myosin preparation was homogeneous and highly purified. We proposed that the use of tilapia myosin has some advantages for studies on the muscular protein of fish, particularly on its structure and function.