Chen Z, Schwartz B, Williams N K, Li R, Klinman J P, Mathews F S
Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Biochemistry. 2000 Aug 15;39(32):9709-17. doi: 10.1021/bi000639f.
Copper amine oxidases (CAOs) catalyze the two-electron oxidation of primary amines to aldehydes, utilizing molecular oxygen as a terminal electron acceptor. To accomplish this transformation, CAOs utilize two cofactors: a mononuclear copper, and a unique redox cofactor, 2,4,5-trihydroxyphenylalanine quinone (TPQ or TOPA quinone). TPQ is derived via posttranslational modification of a specific tyrosine residue within the protein itself. In this study, the structure of an amine oxidase from Hansenula polymorpha has been solved to 2.5 A resolution, in which the precursor tyrosine is unprocessed to TPQ, and the copper site is occupied by zinc. Significantly, the precursor tyrosine directly ligands the metal, thus providing the closest analogue to date of an intermediate in TPQ production. Besides this result, the rearrangement of other active site residues (relative to the mature enzyme) proposed to be involved in the binding of molecular oxygen may shed light on how CAOs efficiently use their active site to carry out both cofactor formation and catalysis.
铜胺氧化酶（CAOs）催化伯胺的双电子氧化生成醛，利用分子氧作为末端电子受体。为实现这一转化，CAOs利用两种辅因子：单核铜和一种独特的氧化还原辅因子，2,4,5-三羟基苯丙氨酸醌（TPQ或TOPA醌）。TPQ是通过蛋白质自身特定酪氨酸残基的翻译后修饰产生的。在本研究中，多形汉逊酵母胺氧化酶的结构已解析至2.5埃分辨率，其中前体酪氨酸未加工成TPQ，且铜位点被锌占据。值得注意的是，前体酪氨酸直接与金属配位，从而提供了迄今为止TPQ生成过程中中间体最接近的类似物。除此之外，其他被认为参与分子氧结合的活性位点残基（相对于成熟酶）的重排，可能有助于揭示CAOs如何有效利用其活性位点进行辅因子形成和催化。
