Parés X, Llorens R, Arús C, Cuchillo C M
Eur J Biochem. 1980 Apr;105(3):571-9. doi: 10.1111/j.1432-1033.1980.tb04534.x.
The chemical modification of bovine pancreatic ribonuclease A by 6-chloropurine 9-beta-D-ribofuranosyl 5'-monophosphate was studied under several reaction conditions. The reaction, at pH 7.3, 40 degrees C and a nucleotide: enzyme molar ratio of 60, showed a high degree of specificity in comparison to those corresponding to the base or the nucleoside. The main derivative was isolated by means of CM-cellulose chromatography. Subtilisin cleavage of this derivative showed that the substitution had taken place in the S-peptide moiety. Tryptic digestion of the S-peptide indicated that a lysine residue had been modified. Enzymatic and physico-chemical considerations showed that the actual site of reaction was the alpha-amino group of Lys-1. The structural and kinetic properties of the derivative are consistent with the existence of a phosphate-binding sub-site near the N-terminal region of the enzyme.
在几种反应条件下研究了6-氯嘌呤9-β-D-呋喃核糖基5'-单磷酸对牛胰核糖核酸酶A的化学修饰。在pH 7.3、40℃且核苷酸与酶的摩尔比为60的条件下进行的反应，与相应的碱基或核苷相比显示出高度的特异性。主要衍生物通过CM-纤维素色谱法分离。该衍生物的枯草杆菌蛋白酶裂解表明取代发生在S-肽部分。S-肽的胰蛋白酶消化表明一个赖氨酸残基已被修饰。酶学和物理化学方面的考虑表明，实际反应位点是Lys-1的α-氨基。该衍生物的结构和动力学性质与酶N端区域附近存在磷酸盐结合亚位点一致。
