Hurst J H, Billingsley M L, Lovenberg W
Biochem Biophys Res Commun. 1984 Jul 31;122(2):499-508. doi: 10.1016/s0006-291x(84)80061-3.
Radioactivity from 3H-[methyl]-S-adenosyl-L-methionine (AdoMet) was covalently bound to protein-O-carboxylmethyltransferase and phenylethanolamine N-methyltransferase following 10-15 min irradiation by short-wave ultraviolet light. This photoaffinity binding of 3H-[methyl]-AdoMet was blocked by S-adenosylhomocysteine and sinefungin, but was not affected by 5 mM dithiothreitol. The binding was also inhibited by including methyl acceptors such as calmodulin (protein-O-carboxylmethyltransferase) or phenylethanolamine (phenylethanolamine N-methyltransferase) in the photoaffinity incubation. Staphlococcus V8 protease digests of 3H-[methyl]-AdoMet/enzyme complexes revealed that the primary structure around the AdoMet binding site is different in these two enzymes. Thus, protein-O-carboxylmethyltransferase, a large molecule methyltransferase, can covalently bind 3H-[methyl]-AdoMet in a manner similar to that of phenylethanolamine-N-methyltransferase.
在短波紫外光照射10 - 15分钟后，3H-[甲基]-S-腺苷-L-甲硫氨酸（AdoMet）的放射性与蛋白质-O-羧甲基转移酶和苯乙醇胺N-甲基转移酶共价结合。3H-[甲基]-AdoMet的这种光亲和结合被S-腺苷同型半胱氨酸和杀稻瘟菌素阻断，但不受5 mM二硫苏糖醇影响。在光亲和孵育中加入甲基受体如钙调蛋白（蛋白质-O-羧甲基转移酶）或苯乙醇胺（苯乙醇胺N-甲基转移酶）也会抑制这种结合。3H-[甲基]-AdoMet/酶复合物的葡萄球菌V8蛋白酶消化产物显示，这两种酶中AdoMet结合位点周围的一级结构不同。因此，蛋白质-O-羧甲基转移酶，一种大分子甲基转移酶，能够以与苯乙醇胺-N-甲基转移酶类似的方式共价结合3H-[甲基]-AdoMet。
