Muhlrad A, Friedman M
Muscle Nerve. 1978 Nov-Dec;1(6):471-8. doi: 10.1002/mus.880010606.
Young rats treated with 10 to 14 daily injections of 2,4-dichlorophenoxyacetate (2,4-D) developed a myopathy mainly involving fast muscles. Myosin isolated from the gastrocnemius muscles of treated and normal control animals differed in several respects. The Ca2+- and Mg2+-mediated ATPases were higher in myopathic muscle myosin than in normals. Alkylation of thiols by N-ethylmaleimide (NEM) induced an increase of Ca2+-activated ATPase that was higher in normal than in myopathic myosin. Trinitrophenylation of reactive amino groups by 2,4,6-trinitrobenzene sulfonate (TBS) induced on increase in Mg2+-mediated ATPase in both preparations, but the increase was higher in normals. Although the heavy- and light-chain pattern was identical in normal and myopathic myosin, during storage at 0 degrees C the relative amount of myopathic L2 light chain decreased. Myosins fragmented either by limited proteolysis with trypsin and chymotrypsin or by specific cleavage at tryptophanyl and cysteinyl peptide bonds showed differences on sodium dodecylsulfate (SDS)-polyacrylamide-gel electrophoresis. The results indicate that there is a change in the heavy chains of myosin isolated from the gastrocnemius muscle in 2,4-D-induced rat myopathy.
用2,4-二氯苯氧乙酸（2,4-D）每日注射10至14天处理的幼鼠会发生一种主要累及快肌的肌病。从处理过的动物和正常对照动物的腓肠肌中分离出的肌球蛋白在几个方面存在差异。肌病性肌肉肌球蛋白中由Ca2+和Mg2+介导的ATP酶活性高于正常肌肉。N-乙基马来酰亚胺（NEM）对硫醇的烷基化作用会导致Ca2+激活的ATP酶活性增加，正常肌球蛋白中的增加幅度高于肌病性肌球蛋白。2,4,6-三硝基苯磺酸（TBS）对反应性氨基的三硝基苯基化作用会使两种制剂中Mg2+介导的ATP酶活性增加，但正常制剂中的增加幅度更高。尽管正常和肌病性肌球蛋白的重链和轻链模式相同，但在0℃储存期间，肌病性L2轻链的相对含量会降低。通过胰蛋白酶和糜蛋白酶的有限蛋白水解或在色氨酸和半胱氨酸肽键处的特异性切割而片段化的肌球蛋白在十二烷基硫酸钠（SDS）-聚丙烯酰胺凝胶电泳上显示出差异。结果表明，在2,4-D诱导的大鼠肌病中，从腓肠肌分离出的肌球蛋白重链发生了变化。
