Nitric Oxide-reducing Activity of Alcaligenes faecalis Cytochrome cd
1972 Volume 72 Issue 1 Pages 57-64
Details
1972 Volume 72 Issue 1 Pages 57-64
Cytochrome cd of Alcaligenes faecalis, which has been found to be a nitrite reductase, was found to have a NO-reducing activity which converts NO to N2O, when ascorbate-phenazine methosulfate was used as an electron donor system. Some characteristics of the reduction of NO by cytochrome cd were examined, comparing with those by the particulate-bound NO-reductase.
(1) The specific activity was about 500μl NO-uptake (or 250μl N2O-output)/hr/mg of cytochrome cd at pH 7 and at 10% NO in the gas phase of the reaction vessel.
(2) The optimum pH for the reduction of NO by cytochrome cd was 5.5, which is similar to that by the particulate-bound NO-reductase.
(3) The NO-reducing activity of the particulate-bound enzyme was inhibited by more than 20% of NO in the gas phase, while that of cytochrome cd was not saturated even at 60% of NO in the gas phase.
(4) Effects of some inhibitors were examined upon the reduction of NO. Cyanide, azide or diethyldithiocarbamate inhibited the reduction of NO by particulate-bound NO-reductase stronger than that by cytochrome cd.
