Comparative Studies on the Enzymic Properties and Thermal Stabilities of N-Ethylmaleimide Modified Myosins from Fish Dorsal and Rabbit Skeletal Muscles
1979 Volume 45 Issue 12 Pages 1503-1512
Details
1979 Volume 45 Issue 12 Pages 1503-1512
The enzymic properties and thermal stabilities of native and N-ethylmaleimide (NEM) modified myosins have been compared between preparations from some fish species and rabbit.
1) 0.4-1.6mol SH residue per 105g of myosin was found to be modified with NEM under the condition employed in this experiment.
2) Changes of Ca-and EDTA-ATPase activities of fish myosin through NEM modification were essentially the same as those of rabbit myosin.
3) The Ca-ATPase activity of NEM modified fish myosin was shown to be similar to that of NEM modified rabbit myosin in the following respects: the KCl concentration dependence, pH dependence and ARRHENIUS activation energy.
4) The inactivation rate of Ca-ATPase activity of fish myosin was increased by about twofold by NEM modification. On the other hand, the rate of rabbit myosin was little affected by NEM modification.
These results strongly suggested that the fish myosin has the identical fast reacting sulfhydryl groups (SH1) which was previously found in rabbit myosin and the SH1 groups may play some role in the stability of ATPase.
A discussion was carried out on the similarities of biochemical properties between NEM modified fish myosin and myosin preparation from frozen bigeye tuna muscle which have previously been reported.
