Bovine thymus poly(adenosine diphosphate ribose) polymerase. Physical properties and binding to DNA.
Bovine thymus poly(adenosine diphosphate ribose) polymerase. Physical properties and binding to DNA.
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牛胸腺聚（腺苷二磷酸核糖）聚合酶。
DOI：
10.1016/s0021-9258(18)43723-4
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
T. Kamiya
中科院分区：
文献类型：
--
作者：
H. Ohgushi;K. Yoshihara;T. Kamiya
纯化的牛胸腺多聚(二磷酸腺苷核糖)聚合酶是一种单体蛋白，经十二烷基硫酸钠凝胶电泳法、分析超速离心法和凝胶过滤法测定，其相对分子质量约为13万。较高的摩擦比(1.81)表明该分子具有拉长的形状，或高溶剂化，或两者兼而有之。该酶是一种碱性蛋白质，等电点为9.8，氨基酸分析表明其赖氨酸含量较高。酶的活性依赖于双链DNA，并且只与DNA上的单链或双链断裂相关。滤膜结合实验表明，DNA的酶激活效率与其酶结合效率具有较好的相关性。因此，从粗酶组份中分离出的DNA组分(活性DNA)具有非常高的酶激活效率主要是由于其高的酶结合效率。单链DNA和肝素对酶与双链DNA的结合有很强的抑制作用，而竞争性抑制剂不影响结合。我们解释这些结果表明，酶与双链DNA的结合是其催化活性的先决条件，具有双重功能：(A)将酶定位在特定的结合部位，如DNA上的单链或双链断裂；(B)诱导酶的活性构象。
Purified bovine thymus poly(adenosine diphosphate ribose) polymerase is a monomeric protein with a single polypeptide chain having a molecular weight of approximately 130,000, determined by sodium dodecyl sulfate-gel electrophoresis, analytical ultracentrifugation, and gel filtration. A high frictional ratio (1.81) indicated that the molecule has an elongated shape, or a high solvation, or both. The enzyme is a basic protein (pI 9.8), and amino acid analysis showed a relatively high lysine content. The enzyme activity is dependent on double-stranded DNA and is solely correlated with single- or double-stranded breaks on the DNA. Filter binding assay technique showed that the enzyme-activating efficiency of DNA correlated sufficiently with its enzyme-binding efficiency. Thus, a very high enzyme-activating efficiency of a DNA fraction (active DNA) which was separated from the crude enzyme fraction is mainly due to its high enzyme-binding efficiency. It was also shown that single-stranded DNA and heparin had a strong inhibitory effect on the binding of the enzyme to double-stranded DNA, whereas competitive inhibitors did not affect the binding, We interpret these results to indicate that the binding of the enzyme to double-stranded DNA is a prerequisite step to its catalytic activity and has a dual function: (a) to position the enzyme on specific binding sites such as single- or double-stranded breaks on the DNA, and (b) to induce an active conformation of the enzyme.