González C, González G, Avila J, Pérez M D, Brito N, Siverio J M
Dapartamento de Bioquímica y Biología Molecular, Universidad de La Laguna, Tenerife, Canarias, Spain.
Microbiology (Reading). 1994 Oct;140 ( Pt 10):2633-7. doi: 10.1099/00221287-140-10-2633.
The addition of nitrite, the product of the reaction catalysed by nitrate reductase, to cell suspensions of the yeast Hansenula anomala caused a reversible inactivation of NADPH-dependent nitrate reductase activity. The haem- and Mo-dependent and Mo-dependent activities of nitrate reductase, determined with the non-physiological electron donors FMNH2 and reduced methyl viologen respectively, were less affected. A similar inactivation was found with the proton ionophores 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. The inactive enzyme was found in the particulate fraction and cosedimented with the mitochondrial fraction. When the NADPH-dependent nitrate reductase activity was restored in vivo the enzyme was found in the soluble fraction. The inactivation of nitrate reductase by nitrite, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone was dependent on the external pH. The treatment of isolated mitochondria at alkaline pH with Triton X-100 solubilized about 30% of the inactive enzyme.
向异常汉逊酵母的细胞悬液中添加硝酸盐还原酶催化反应的产物亚硝酸盐，会导致依赖NADPH的硝酸盐还原酶活性发生可逆失活。分别用非生理性电子供体FMNH₂和还原型甲基紫精测定的硝酸盐还原酶的血红素依赖性、钼依赖性和仅钼依赖性活性受影响较小。在用质子离子载体2,4-二硝基苯酚和羰基氰化物间氯苯腙处理时也发现了类似的失活现象。失活的酶存在于颗粒部分，并与线粒体部分共沉降。当依赖NADPH的硝酸盐还原酶活性在体内恢复时，该酶存在于可溶性部分。亚硝酸盐、2,4-二硝基苯酚和羰基氰化物间氯苯腙对硝酸盐还原酶的失活作用取决于外部pH值。在碱性pH下用Triton X-100处理分离的线粒体，可溶解约30%的失活酶。
