Richards H H, Chiang P K, Cantoni G L
J Biol Chem. 1978 Jun 25;253(12):4476-80.
Adenosylhomocysteine hydrolase (EC 3.3.1.1) from calf liver was purified to homogeneity by crystallization. The purified enzyme exhibited one single component in polyacrylamide gel electrophoresis. But by Ampholine gel electrophoresis, two isoelectric focusing variants were observed, with pI values at 5.8 and 6.0. when subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, one major subunit with a molecular weight of 60,000 was found; five other minor subunit variants were also observed, with molecular weights ranging between 50,000 and 57,000. These minor subunit variants comprised approximately 15% of the total protein applied. The molecular weight of the native enzyme was estimated to be 237,500 by gradient gel electrophoresis. The native enzyme is probably composed of four subunits, each with a molecular weight of not more than 60,000. Amino acid analyses of the purified enzyme revealed the presence of 1.2 residues of glucosamine/mol of enzyme, in addition to all of the common amino acids. The presence of enzyme-bound NAD was confirmed, probably 1 NAD molecule bound/enzyme subunit. In addition to adenosine, 3-deazaadenosine was found to be an effective substrate as well in the direction of synthesis.
通过结晶法将小牛肝脏中的腺苷同型半胱氨酸水解酶（EC 3.3.1.1）纯化至同质。纯化后的酶在聚丙烯酰胺凝胶电泳中呈现单一成分。但在两性电解质凝胶电泳中，观察到两个等电聚焦变体，其pI值分别为5.8和6.0。当在十二烷基硫酸钠存在下进行聚丙烯酰胺凝胶电泳时，发现一个分子量为60,000的主要亚基；还观察到其他五个次要亚基变体，分子量在50,000至57,则些次要亚基变体约占所加总蛋白的15%。通过梯度凝胶电泳估计天然酶的分子量为237,500。天然酶可能由四个亚基组成，每个亚基的分子量不超过60,000。对纯化酶的氨基酸分析表明，除了所有常见氨基酸外，每摩尔酶还含有1.2个氨基葡萄糖残基。证实了酶结合的NAD的存在，可能每个酶亚基结合1个NAD分子。除腺苷外，还发现3-脱氮腺苷在合成方向上也是一种有效的底物。
