Merli A, Brodersen D E, Morini B, Chen Z, Durley R C, Mathews F S, Davidson V L, Rossi G L
Istituto di Scienze Biochimiche, Universita di Parma, Parma, Italy.
J Biol Chem. 1996 Apr 19;271(16):9177-80. doi: 10.1074/jbc.271.16.9177.
Enzymatic and electron transfer activities have been studied by polarized absorption spectroscopy in single crystals of both binary and ternary complexes of methylamine dehydrogenase (MADH) with its redox partners. Within the crystals, MADH oxidizes methylamine, and the electrons are passed from the reduced tryptophan tryptophylquinone (TTQ) cofactor to the copper of amicyanin and to the heme of cytochrome c551i via amicyanin. The equilibrium distribution of electrons among the cofactors, and the rate of heme reduction after reaction with substrate, are both dependent on pH. The presence of copper in the ternary complex is not absolutely required for electron transfer from TTQ to heme, but its presence greatly enhances the rate of electron flow to the heme.
通过偏振吸收光谱法，对甲胺脱氢酶（MADH）与其氧化还原伙伴形成的二元和三元复合物的单晶中的酶活性和电子转移活性进行了研究。在晶体内部，MADH氧化甲胺，电子从还原型色氨酸-色氨酸醌（TTQ）辅因子传递至氨腈蓝蛋白的铜，并通过氨腈蓝蛋白传递至细胞色素c551i的血红素。辅因子之间电子的平衡分布以及与底物反应后血红素的还原速率均取决于pH值。从TTQ到血红素的电子转移并非绝对需要三元复合物中铜的存在，但其存在极大地提高了电子流向血红素的速率。
