MECHANISM OF ACTION OF POLYMERIC AURINTRICARBOXYLIC ACID, A POTENT INHIBITOR OF PROTEIN-NUCLEIC ACID INTERACTIONS
MECHANISM OF ACTION OF POLYMERIC AURINTRICARBOXYLIC ACID, A POTENT INHIBITOR OF PROTEIN-NUCLEIC ACID INTERACTIONS
复制标题
DOI：
10.1021/bi00559a023
复制
发表时间：
1980-01-01
期刊：
影响因子：
2.9
通讯作者：
SCHLEICH, T
中科院分区：
文献类型：
--
作者：
GILBERTOGONZALEZ, R;HAXO, RS;SCHLEICH, T
用质子磁共振波谱研究了聚合金精三羧酸（ATA）抑制蛋白质-核酸复合物形成的机理。该方法是合成全氘代ATA，然后用100 MHz PMR研究其与牛胰腺RNA酶A（EC 3.1.4.22）（一种模型核酸结合蛋白）的相互作用。ATA与RNA酶的结合引起组氨酰残基12和119的C（2）-H-共振的化学位移变化和谱线增宽，这两个残基都位于活性位点，而位于蛋白质结构外部的组氨酰残基105的C（2）-H-共振不受影响。（除了在高pH下，在这些条件下未观察到组氨酰残基48。）ε-赖氨酰侧链的亚甲基质子也在ATA结合后变宽。聚合ATA从酶的活性位点置换2“-CMP和3”-CMP，如NMR光谱所揭示的。这些观察结果表明，ATA的作用机制涉及核酸和多聚ATA之间的竞争，以结合在蛋白质的活性位点。ESR光谱表明，聚合ATA是一种稳定的自由基，从而占主要的线加宽效应后，结合到蛋白质。这一发现可能提供了一个强有力的手段探测核酸结合位点的蛋白质的PMR光谱。
The mechanism of inhibition of protein-nucleic acid complex formation by polymeric aurintricarboxylic acid (ATA) was investigated by PMR spectroscopy. The approach was the synthesis of totally deuterated ATA, followed by a 100 MHz PMR study of its interaction with bovine pancreatic RNase A (EC 3.1.4.22), a model nucleic acid binding protein. The binding of ATA to RNase elicited chemical shift changes and line broadening in the C(2)-H- resonances of histidyl residues 12 and 119, both of which are located in the active site, whereas that of histidyl residue 105, which resides on the exterior of the protein structure, is unaffected. (Histidyl residue 48 is not observed under these conditions except at high pH.) The .epsilon.-methylene protons of the lysyl side chains were also broadened upon the binding of ATA. Polymeric ATA displaces 2''-CMP and 3''-CMP from the active site of the enzyme as revealed by NMR spectroscopy. These observations suggest that the mechanism of action of ATA involves competition between the nucleic acid and the polymeric ATA for binding in the active site of the protein. ESR spectroscopy reveals that polymeric ATA is a stable free radical, thus accounting for the major line broadening effect upon binding to protein. This finding may provide a powerful means of probing the nucleic acid binding site of proteins by PMR spectroscopy.