Choudary P V
Antibody Engineering Laboratory, University of California, Davis 95616.
Microbios. 1993;74(298):53-7.
Nitrite functioned as an effective inducer of nitrate reductase, the enzyme responsible for the reduction of nitrate in the nitrate assimilation pathway in Candida utilis. Nitrite-induced synthesis of nitrate reductase in C. utilis was repressed by various metabolites of nitrate, including ammonia. Readily-assimilable sources of nitrogen such as ammonia and glutamate exerted a stronger repression on nitrate reductase induction than did less-readily assimilable hydrazine and hydroxylamine. Nitrite-mediated induction of nitrate reductase appeared more sensitive to repression by nitrate metabolites than was nitrate-mediated induction. Based on the inducer-specific differences in the sensitivity of the enzyme to repression by various intermediary metabolites and on other properties, it is proposed that the C. utilis nitrate reductase is either polymorphic or utilizes alternative receptor(s) for binding various gratuitous inducers including nitrite in initiating the induction pathway.
亚硝酸盐是产朊假丝酵母硝酸盐同化途径中负责硝酸盐还原的硝酸还原酶的有效诱导剂。亚硝酸盐诱导产朊假丝酵母合成硝酸还原酶的过程受到硝酸盐的各种代谢产物（包括氨）的抑制。像氨和谷氨酸这样易于同化的氮源对硝酸还原酶诱导的抑制作用比不易于同化的肼和羟胺更强。亚硝酸盐介导的硝酸还原酶诱导似乎比硝酸盐介导的诱导对硝酸盐代谢产物的抑制更敏感。基于该酶对各种中间代谢产物抑制的敏感性存在诱导剂特异性差异以及其他特性，有人提出产朊假丝酵母硝酸还原酶要么是多态性的，要么利用替代受体来结合包括亚硝酸盐在内的各种 gratuitous 诱导剂以启动诱导途径。
