Studies on blue copper proteins and metal complexes as electron acceptors form a reduced enzyme

用循环伏安法测定了甲基单胞菌J甲胺脱氢酶对5种蓝铜蛋白的电子转移速率。从这些铜蛋白到甲胺脱氢酶的电子转移速率常数(E_&lt；1/2&gt；=约100 mV(NHE))的顺序如下：产碱菌属的天青素。(AZ-AS；E_&lt；1/2&gt；=270 mM(NHE))和GT；amilanin(Am-Me；248 mV)和Gt；azurin-1(Az-MJ1；278 mV)。Az-Az作为电子受体的活性比Az-MJ2高7.5倍，而来自甲基单胞菌AM1的假天青素(Paz-Ac；260 mV)几乎没有这种活性。这些发现不是由于蓝铜蛋白的氧化还原电势，而是蛋白质序列的比对。尤其是蓝铜蛋白中与铜(II)结合的咪唑基团周围的疏水分子似乎对甲胺脱氢酶的作用很重要。

The electron-transfer rates form Methylomonas J methylamine dehyrogenase to five blue copper proteins have been evaluated by cyclic voltammetry. The order of the electron-transfer rate constants from these copper proteins to methylamine dehydrogenase (E_<1/2>=ca.+100mV(NHE))) is as follows : azurin from Alcaligenes sp. (Az-As ; E_<1/2>=+270 mM(NHE)) > amicyanin from Methylobacterium extorquens AM1 (Am-Me ; +248 mV) > azurin-1 from Methylomonas J (Az-MJ1 ; +278 mV). Az-Az exhibited the higher activity bya factor of 7.5 as electron acceptors than Az-MJ2, but pseudoazurin from Methylomonas extorquens AM1 (pAz-Ac ; +260 mV) had hardly the activity. These findings are not due to the redox potentiols of blue copper proteins but the alignment of protein sequences. Espectially the hydrophobic phtch around hystidine imidazole guroup bound to Cu(II) in blue copper protein seems to be important to interact with methylamine dehydrogenase.