The Primary Structure of the Heavy Chain of Chicken Gizzard Myosin

为了在分子水平上研究肌肉收缩，可能有必要揭示肌球蛋白的一级结构，肌球蛋白是收缩装置的主要组成部分。在本研究中，我们测定了鸡胆肌球蛋白S-1重链的N-端203-残基和C-端203-残基序列。肌球蛋白在三磷酸腺苷存在下用N-iodoacetyl-N‘-(5-sulfo-1-naphtyl)ethylenediamine(缩写为IAEDANS)修饰。通过Sephadex G-100凝胶过滤和CM 52柱层析，从修饰肌球蛋白的胰酶解液中分离得到一条24kodalton的荧光片段。用常规方法测定该片段的氨基酸序列。该片段含有203个氨基酸残基和一个封闭的N-末端，被归属为重链的N-末端部分。N-三甲基赖氨酸与…的同源位置更多的是骨骼肌球蛋白，但没有-N-单甲基赖氨酸。兔骨骼肌球蛋白重链的Trp-130被肌球蛋白中的谷氨酰胺取代，该重链被认为是ATP结合残基之一。该片段的CyS-93为氨基酸残基，其与IAEDANS的作用改变了肌球蛋白的ATPase活性。在没有ATP的情况下，用IAEDANS对肌球蛋白进行修饰，并用木瓜酶进行消化。从该酶中分离出MR=23,800的荧光片段，并如上所述进行测序。根据与骨骼肌球蛋白序列的同源性，该片段含有203个氨基酸残基，可归属为S-1重链的C-末端。该片段的C末端53个残基是肌球蛋白的颈部部分，含有13个带正电荷的残基，没有带负电荷的残基。我们正在对位于上述两个片段之间的50千道尔顿片段进行测序。肌球蛋白头的初级结构可能在不久的将来被揭示。较少

It may be necessary to reveal the primary structure of myosin, a major component of the contractile apparatus, for studies of muscle contraction at the molecular level. In the present study, we determined the N-terminal 203-residue and C-terminal 203-residue sequences of the S-1 heavy chain of chicken gizzard myosin.1. Gizzard myosin was modified with N-iodoacetyl-N'-(5-sulfo-1-naphtyl)ethylenediamine (abbreviated as IAEDANS) in the presence of ATP. From the tryptic digest of the modified myosin, a fluorescent fragment (24 kilodalton) was isolated by gel filtration on a Sephadex G-100 column in the presence of 5 M guanidine-HCl followed by chromatography on a CM 52 column in the presence of 8 M urea. The amino acid sequence of the fragment was determined by conventional methods. The fragment contained 203 amino acid residues and a blocked N-terminus, and was assigned as an N-termnal part of the heavy chain. An <epsilon> -N-trimethyllysine was recognized at the homologous position with … More skeletal myosin, but no <epsilon> -N-monomethyllysine. Trp-130 of rabbit skeletal myosin heavy chain which is considered to be one of ATP-binding residue was replaced by gultamine in gizzard myosin. Cys-93 of the fragment was the amino acid residue whose reaction with IAEDANS alters the ATPase activity of gizzard myosin.2. Gizzard myosin was modified with IAEDANS in the absence of ATP, and digested with papain. From the digest, a fluorescent fragment of Mr=23,800 was isolated, and sequenced as described above. The papain-fragment contained 203 amino acid residues which could be assigned as C-terminal part of the S-1 heavy chain based on the homology with the sequence of skeletal myosin. The C-terminal 53 residues of this fragment, constituting the neck part of myosin, contained 13 positively charged residues but no negatively charged residue.3. We are sequencing the 50 kilodalton fragment which lies between the above two fragments. The primary structure of the gizzard myosin head could be revealed in the near future. Less