Nakano K, Fukui T, Matsubara H
J Biochem. 1980 Mar;87(3):919-27. doi: 10.1093/oxfordjournals.jbchem.a132822.
To elucidate the structural similarity between alpha-glucan phosphorylases from different sources, the amino acid sequences of the cysteinyl regions in potato phosphorylase were determined, and compared with the complete sequence of the rabbit muscle enzyme. Cysteinyl peptides were purified by covalent chromatography based on thiol-disulfide exchange. Potato phosphorylase was coupled to Thiopropyl-Sepharose 6B in the presence of urea, and, after tryptic digestion, 10 distinct cysteinyl peptides which accounted for all the cysteine present in the enzyme were finally isolated in high yields. From the sequence comparison, all of the peptides surrounding the cysteinyl residues in the potato enzyme are homologous with widely distributed specific regions in the rabbit muscle enzyme, although only 4 of 10 cysteinyl residues are conserved between the two enzymes. These observations, in addition to the previously established homology in the cofactor site, show that potato and rabbit muscle phosphorylases are similar in terms of the primary structure. The different properties of cysteinyl residues in the two enzymes are discussed based on the present sequence comparison and the recent X-ray crystallographic data for the rabbit muscle enzyme.
为阐明不同来源的α-葡聚糖磷酸化酶之间的结构相似性，测定了马铃薯磷酸化酶中半胱氨酸区域的氨基酸序列，并与兔肌肉酶的完整序列进行了比较。基于硫醇-二硫键交换，通过共价色谱法纯化半胱氨酸肽。在尿素存在的情况下，将马铃薯磷酸化酶与硫丙基-琼脂糖6B偶联，经胰蛋白酶消化后，最终以高产率分离出10种不同的半胱氨酸肽，它们占该酶中所有的半胱氨酸。通过序列比较发现，马铃薯酶中围绕半胱氨酸残基的所有肽与兔肌肉酶中广泛分布的特定区域同源，尽管两种酶之间10个半胱氨酸残基中只有4个是保守的。这些观察结果，除了先前确定的辅因子位点的同源性外，还表明马铃薯和兔肌肉磷酸化酶在一级结构方面是相似的。基于目前的序列比较和兔肌肉酶最近的X射线晶体学数据，讨论了两种酶中半胱氨酸残基的不同特性。
