摘要
分离了扇贝闭壳肌肌钙蛋白,其分子量为46(InI),40(TnT),和22(TnC)kD.肌球蛋白B含有主要的收缩蛋白质与调节蛋白质,在有Ca2+和ATP存在时,它会发生超沉淀作用.经低离子强度溶液反复沉淀处理,即失去Ca2+-敏感性,成为去敏肌球蛋白B.在Ca2+和ATP作用下,它仍可发生超沉淀作用,但仅及最大活性的50%.若加入肌钙蛋白,则反应活性可完全恢复.兔骨骼肌肌钙蛋白可替代扇贝闭壳肌肌钙蛋白.这表明扇贝闭壳肌兼有肌动蛋白相关调节和肌球蛋白相关调节.
Troponins with molecular weights of 46(TnI),40(TnT)and 22 (TnC)kD have been isolated from scallop adductor muscle.In the presence of Ca 2+ and ATP,scallop myosin B,containing major contractile and regulatory proteins,can produce superprecipitation,showing two maximal pH,Ca 2+ sensitivity and substrate inhibition.After washing with low ionic strength solution several times,myosin B loses Ca 2+ sensitivity and becomes a desensitized myosin B.Ca 2+ and ATP can still induce its superprecipitation by 50 percent of maximal activity.Adding scallop troponins into reaction system,the desensitized myosin B can restore superprecipitation completely.In addition,rabbit skeletal troponins can substitute for scallop adductor troponins in inducing myosin B superprecipitation.The results suggest that the actin linked and myosin linked regulatory mechanisms coexist in scallop adductor muscle.