Isolation of Paracoccus denitrificans cytochrome cd1: comparative kinetics with other nitrite reductases.
Isolation of Paracoccus denitrificans cytochrome cd1: comparative kinetics with other nitrite reductases.
复制标题
脱氮副球菌细胞色素 cd1 的分离：与其他亚硝酸盐还原酶的动力学比较。
DOI：
10.1016/0003-9861(82)90277-6
复制
发表时间：
1982
影响因子：
3.9
通讯作者：
Rea,TM
中科院分区：
文献类型：
--
作者：
Timkovich,R;Dhesi,R;Martinkus,KJ;Robinson,MK;Rea,TM
The dissimilatory nitrite reductase of the cytochromecd1type was purified fromParacoccus denitrificans(ATCC 13543) by a novel procedure that avoided conventional ion-exchange techniques. The characterization of this enzyme was extended to include amino acid composition, extinction coefficients, and kinetic properties not previously reported. Cytochromescd1fromAlicaligenes faecalisandPseudomonas aeruginosawere also isolated and assayed with electron donor proteins. The enzymes from all three sources were shown to obey the same integrated rate law. Cross-reactivities were measured in which a reduced donor protein from one strain was assayed with cytochromecd1from another strain using nitrite as ultimate acceptor. Donors includedc-type cytochromes and azurins. In general, the enzymes showed specificity for a donor from the same strain; interspecies cross-reactions were typically slower on the order of 10-fold than corresponding native rates. Notable exceptions wereParacoccuscytochromecd1, which alone reacted with eukaryotic horse cytochromecat appreciable rates, and thePseudomonas cd1-Alcaligenesc554 reaction, which was 4-fold faster than the nativeAlcaligenes cd1-Alcaligenesc554 reaction. For all three enzymes, competitive kinetics were measured in which the alternative substrates, nitrite and oxygen, competed for enzyme in the same assay. It was found that the competitive kinetics were dominated by nonenzymatic reactions involving an enzyme product, nitric oxide.
