INHIBITION OF NITROGENASE-CATALYZED REDUCTIONS
INHIBITION OF NITROGENASE-CATALYZED REDUCTIONS
复制标题
DOI：
10.1016/0005-2728(73)90270-3
复制
发表时间：
1973-01-01
期刊：
影响因子：
--
通讯作者：
BURRIS, RH
中科院分区：
文献类型：
--
作者：
HWANG, JC;CHEN, CH;BURRIS, RH
在电子受体和抑制剂的浓度不影响固氮酶催化ATP水解的条件下，研究了固氮酶催化还原的抑制作用，电子受体的浓度至少是其米氏常数的1.8倍，以降低放氢的影响.根据Lineweaver-Burk作图，CO与N2、乙炔和NaN 3之间为非竞争性，不抑制H2的释放，H2竞争性抑制N2的固定，但不抑制叠氮化物、乙炔、氰化物、异氰化物和H+的还原，乙炔和氰化物与N2之间为非竞争性，乙炔和叠氮化物之间为非竞争性，而H2与N2之间为非竞争性。氰化物和甲基异氰化物与NaN 3竞争。根据这些观察结果，提出固氮酶复合物的5个位点或修饰位点：（1）N2和H2位点，（2）乙炔位点，（3）叠氮化物、氰化物和甲基异氰化物位点，（4）CO位点，（5）H+位点。
Inhibition of nitrogenase-catalyzed reductions was studied under such conditions that the concentration of electron acceptors and inhibitors did not affect nitrogenase-catalyzed ATP hydrolysis, and the concentration of the electron acceptor was at least 1.8 times its Michaelis constant to reduce the effect of H2evolution. Thus, the effects were centered on the reduction site.Based on Lineweaver-Burk plots, CO was noncompetitive with N2, acetylene and NaN3and did not inhibit H2evolution; H2inhibited N2fixation competitively, but it did not inhibit reduction of azide, acetylene, cyanide, isocyanide, and H+; acetylene and cyanide were noncompetitive with N2; acetylene and azide acted noncompetitively with each other; cyanide and methylisocyanide were competitive with NaN3. According to these observations, the following five sites or modified sites are proposed for the nitrogenase complex: (1) N2and H2site, (2) acetylene site, (3) azide, cyanide and methylisocyanide site, (4) CO site, (5) H+site.