Enzymatic properties, metal composition and SH-group reactivity of fragmented sarcoplasmic reticulum isolated from rabbit skeletal muscle.

Comparison of properties of fragmented sarcoplasmic reticulum samples isolated by several methods is reported. It was found that the protein composition does not differ significantly in samples which were or were not washed with 0.6 M KCl when isolated. In the case of samples washed with KCl solution the Zn concentration, the Ca/Mg ratio (determined from experimental data), acetylcholinesterase and superoxide dismutase activities were higher whereas Ca+Mg-activated ATPase and p-nitrophenylphosphatase activities were lower than those of samples which were not washed with 0.6 M KCl. In the latter samples the amount of SH-groups and the reactivity of fast SH-s are higher in Ca+EGTA containing media than in media containing only EGTA. In contrast in the case of samples washed with KCl solution the results are the opposite. In conclusion, washing of FSR with 0.6 M KCl alters the metal composition, enzymatic properties, SH-group reactivity and as a result of these probably the conformation of the protein samples, as well.