Borchardt R T, Thakker D R
J Med Chem. 1975 Feb;18(2):152-8. doi: 10.1021/jm00236a008.
Several N-acyl-3,5-dimethoxy-4-hydroxyphenylalkylamines have been synthesized and evaluated for their ability to inactive catechol 9-methyltransferase (COMT). N-iodoacetyl-3,5-dimethoxy-4-hydroxyphenylethylamine was found to rapidly and irreversibly inactivate this enzyme. The corresponding N-bromoacetyl derivative also produced inactivation of COMT but at a slower rate than the N-iodoacetyl derivative. The N-acetyl and N-fumaryl derivatives were completely inactive. The inactivation of COMT by these reagents appears to proceed by a unimolecular reaction within a dissociable complex rather than by a nonspecific bimolecular reaction. The proximity of the amino acid residue being modified relative to the site which binds the aromatic portion of these inhibitors was determined using N-iodoacetylphenylakylamines of varying chain length. The number of methylene carbons separating the aromatic ring and the iodoacetamide moiety in these inhibitors did not greatly influence the binding to COMT nor did it affect how rapidly the enzyme was inactivated. From these observations it was concluded that the amino acid moiety being modified by this class of affinity labeling reagents must be relatively close to or part of the site which binds the aromatic region of these inhibitors.
已经合成了几种N-酰基-3,5-二甲氧基-4-羟基苯烷基胺，并对其使儿茶酚-O-甲基转移酶（COMT）失活的能力进行了评估。发现N-碘乙酰基-3,5-二甲氧基-4-羟基苯乙胺能快速且不可逆地使该酶失活。相应的N-溴乙酰基衍生物也能使COMT失活，但速率比N-碘乙酰基衍生物慢。N-乙酰基和N-富马酰基衍生物则完全无活性。这些试剂使COMT失活的过程似乎是通过可解离复合物内的单分子反应进行的，而不是通过非特异性的双分子反应。使用不同链长的N-碘乙酰基苯烷基胺确定了被修饰的氨基酸残基相对于结合这些抑制剂芳香部分的位点的接近程度。这些抑制剂中分隔芳香环和碘乙酰胺部分的亚甲基碳的数量对与COMT的结合影响不大，对酶失活的速度也没有影响。从这些观察结果可以得出结论，被这类亲和标记试剂修饰的氨基酸部分必定相对靠近这些抑制剂芳香区域的结合位点或为该位点的一部分。
