The bound nucleotide of the isolated myofibril.
The bound nucleotide of the isolated myofibril.
复制标题
分离的肌原纤维的结合核苷酸。
DOI：
10.1042/bj0510495
复制
发表时间：
1952
期刊：
影响因子：
--
通讯作者：
S. Perry
中科院分区：
文献类型：
--
作者：
S. Perry
自从Straub和Feuer（1950）报道在球状肌动蛋白（G-肌动蛋白）中存在三磷酸腺苷（ATP）以来，这种蛋白的核苷酸含量一直是大量研究的主题。最初认为ATP在G-肌动蛋白转化为纤维状肌动蛋白（F-肌动蛋白）的过程中被分裂的观点已经被拉基和克拉克（1951）和森特-捷尔吉（1951）的工作所证实，但是这些作者的工作并不支持解聚伴随着ATP再合成的观点。另一方面，Dubuisson和Mathieu（1950）虽然证实了G-肌动蛋白制剂中存在ATP，但在聚合过程中未能检测到磷酸盐分布或游离磷酸盐的任何变化。尽管上述研究者对ATP在肌动蛋白聚合中的作用并不一致，但都证实ATP是正常G-肌动蛋白制品的一种成分，而Snelhman和Gelotte（1951）用色谱技术在G-肌动蛋白或F-肌动蛋白中都不能检测到ATP或腺苷二磷酸（ADP）。这些作者认为，肌动蛋白的辅基是一个含有腺嘌呤和一个迄今尚未确定的碱基的二核苷酸，它可以以富磷酸和贫磷酸的形式出现，分别对应于G-肌动蛋白和F-肌动蛋白。肌动蛋白并不是唯一具有结合腺嘌呤核苷酸特性的蛋白质，因为Buchtal、多伊奇、Knappeis和Munch-Petersen（1949）已经表明，当肌球蛋白和肌动球蛋白用ATP处理时，一些核苷酸以这样的方式结合到蛋白质上，即它不能通过反复洗涤而被去除。到目前为止所提到的研究已经进行了提取纯化的肌原纤维蛋白和完整的肌原纤维的核苷酸含量很少受到关注。Caspersson和Thorell（1942）声称利用紫外线吸收法证明了ATP在静息肌肉I带的定位。然而，不可能确定他们的结果是由于腺嘌呤核苷酸还是由于肌原纤维中存在的少量核酸（佩里，1952）。在较早的通讯中（佩里，1951），描述了一种使用胶原酶分离相对少量肌原纤维的方法。这些制剂的初步分析表明，分离的肌原纤维含有少量的核酸，磷脂和酸不稳定的磷。在本文中，这后者的磷馏分的研究进行了描述，连同一种方法分离肌原纤维在更大的数量，这大大促进了调查。从兔骨骼肌、心肌和大鼠骨骼肌中获得的肌原纤维的酸不稳定磷的量是相当恒定的。在兔骨骼肌中，它是由ATP和ADP与肌原纤维结合而产生的，这种结合使这些核苷酸不能被通常攻击它们的酶所接近。该核苷酸部分主要由ADP组成，并且存在的量与其与分离的肌原纤维中的F-肌动蛋白相关的观点是相容的。
Since Straub & Feuer (1950) reported the presence of adenosinetriphosphate (ATP) in globular actin (G-actin) the nucleotide content of this protein has been the subject of considerable investigation. The original claim that ATP was split during the transformation of G-actin to fibrous actin (F-actin) has been substantiated by the work of Laki & Clark (1951) and Szent-Gyorgyi (1951), but the work of these authors does not support the view that depolymerization is accompanied by resynthesis of ATP. On the other hand, Dubuisson & Mathieu (1950), whilst confirming that ATP is present in G-actin preparations, could not detect any change in phosphate distribution or any change in free phosphate during polymerization. Although the above investigators do not agree as to the role of ATP in the polymerization of actin, all confirm that ATP is a component ofnormal G-actin preparations, whereas Snelhman & Gelotte (1951), using chromatographic techniques, were unable to detect any ATP or adenosinediphosphate (ADP) in either G-actin or F-actin. These authors consider that the prosthetic group of actin is a dinucleotide containing adenine and a so-far unidentified base which can occur in phosphate rich and phosphate poor forms, corresponding to G-actin and F-actin respectively. Actin is not alone in its property of binding adenine nucleotides, for Buchtal, Deutsch, Knappeis & Munch-Petersen (1949) have shown that when myosin and actomyosin are treated with ATP, some nucleotide is bound to the protein in such a way that it cannot be removed by repeated washing. The investigations so far mentioned have been carried out on extracted purified myofibrillar proteins and the nucleotide content of the intact myofibril has received little attention. Using ultraviolet absorption methods Caspersson & Thorell (1942) claimed to have demonstrated the localization ofATP in the I band ofresting muscle. It is not possible, however, to decide whether their results were due to adenine nucleotide or to the small amount of nucleic acid which occurs in the myofibril (Perry, 1952). In an earlier communication (Perry, 1951) a method employing collagenase was described for the isolation of myofibrils in comparatively small quantities. Preliminary analyses of these preparations indicated that the isolated myofibril contained small amounts of nucleic acid, phospholipid and acid-labile phosphorus. In the present paper a study of this latter phosphorus fraction is described, together with a method for isolating myofibrils in larger quantities which has considerably facilitated the investigation. The acidlabile phosphorus of myofibrils obtained from skeletal and cardiac muscle of the rabbit, and rat skeletal muscle, is rather constant in amount. In rabbit skeletal muscle it arises from ATP and ADP bound to the myofibril in a manner which renders these nucleotides inaccessible to the enzymes which normally attack them. This nucleotide fraction consists predominantly of ADP, and the quantities present are compatible with the view that it is associated with F-actin in the isolated myofibril.