Gray K A, Davidson V L, Knaff D B
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061.
J Biol Chem. 1988 Oct 5;263(28):13987-90.
Two proteins isolated from Paracoccus denitrificans, the copper-containing electron carrier amicyanin and the pyrroloquinoline quinone-containing enzyme methylamine dehydrogenase, have been shown to form a complex. Complex formation between methylamine dehydrogenase and either oxidized or reduced amicyanin resulted in alterations in the absorbance spectrum of the pyrroloquinoline quinone prosthetic group of methylamine dehydrogenase. Binding of amicyanin to the enzyme exhibited positive cooperativity. Complex formation with methylamine dehydrogenase shifted the oxidation-reduction midpoint potential of amicyanin by 73 mV, from +294 to +221 mV, making electron transfer from amicyanin to cytochrome c551 (Em = +190 mV) thermodynamically possible.
从反硝化副球菌中分离出的两种蛋白质，即含铜电子载体氨腈蛋白和含吡咯喹啉醌的酶甲胺脱氢酶，已被证明能形成复合物。甲胺脱氢酶与氧化型或还原型氨腈蛋白之间形成复合物，导致甲胺脱氢酶的吡咯喹啉醌辅基的吸收光谱发生变化。氨腈蛋白与该酶的结合表现出正协同性。与甲胺脱氢酶形成复合物使氨腈蛋白的氧化还原中点电位从 +294 mV 偏移了 73 mV 至 +221 mV，使得氨腈蛋白向细胞色素 c551（Em = +190 mV）的电子转移在热力学上成为可能。
