Di Donato A, Galletti P, D'Alessio G
Biochemistry. 1986 Dec 30;25(26):8361-8. doi: 10.1021/bi00374a005.
Isoenzymatic forms alpha 2, alpha beta, and beta 2 of bovine seminal ribonuclease are generated by the transformation of beta-type into alpha-type subunit through deamidation of a single amide group [Di Donato, A., & D'Alessio, G. (1981) Biochemistry 20, 7232-7237]. The residue involved in this selective deamidation has been identified as Asn67. Deamidation occurs by formation of a cyclic imide intermediate involving the Gly at position 68. Opening of the cyclic imide may occur on either side of the nitrogen, generating both the normal alpha-aspartyl and an isoaspartyl residue at position 67. The alpha-carboxyl of the isoaspartyl residue is effectively methylated by bovine brain protein carboxylmethyltransferase.
牛精核糖核酸酶的同工酶形式α2、αβ和β2是通过单个酰胺基团的脱酰胺作用将β型亚基转化为α型亚基而产生的[迪多纳托，A.，& 达莱西奥，G.（1981年）《生物化学》20，7232 - 7237]。参与这种选择性脱酰胺作用的残基已被确定为Asn67。脱酰胺作用通过形成涉及68位甘氨酸的环状亚胺中间体而发生。环状亚胺的开环可能发生在氮的两侧，在67位产生正常的α - 天冬氨酰残基和异天冬氨酰残基。异天冬氨酰残基的α - 羧基被牛脑蛋白羧甲基转移酶有效地甲基化。
