DiSpirito A A, Hooper A B
J Biol Chem. 1986 Aug 15;261(23):10534-7.
During oxidation of nitrite, cells of Nitrobacter winogradskyi are shown to catalyze the active exchange of oxygen atoms between exogenous nitrate molecules (production of 15N16/18O3- during incubation of 14N16/18O3-, 15N16O3-, and 15N16O2- in H216O). Little, if any, exchange of oxygens between nitrate and water also occurs (production of 15N16/18O3- during incubation of 15N16O3- and 14N16O2- in H218O). 15N species of nitrate were assayed by 18O-isotope shift in 15N NMR. Taking into account the O-exchange reactions which occur during nitrite oxidation, H2O is seen to be the source of O in nitrate produced by oxidation of nitrite by N. winogradskyi. The data do not establish whether the nitrate-nitrate O exchange is catalyzed by nitrite oxidase (H2O + HNO2----HNO3 + 2H+ + 2e-) or nitrate reductase (HNO3 + 2H+ + 2e-----HNO2 + H2O) or both enzymes in consort. The nitrate-nitrate exchange reaction suggests the existence of an oxygen derivative of a H2O-utilizing oxidoreductase.
在亚硝酸盐氧化过程中，发现维氏硝化杆菌细胞能催化外源硝酸盐分子间氧原子的活性交换（在H₂¹⁶O中，用¹⁴N¹⁶/¹⁸O₃⁻、¹⁵N¹⁶O₃⁻和¹⁵N¹⁶O₂⁻培养时产生¹⁵N¹⁶/¹⁸O₃⁻）。硝酸盐与水之间也会发生少量（如果有的话）的氧交换（在H₂¹⁸O中，用¹⁵N¹⁶O₃⁻和¹⁴N¹⁶O₂⁻培养时产生¹⁵N¹⁶/¹⁸O₃⁻）。通过¹⁵N NMR中的¹⁸O同位素位移来测定硝酸盐的¹⁵N种类。考虑到亚硝酸盐氧化过程中发生的氧交换反应，可以看出H₂O是维氏硝化杆菌将亚硝酸盐氧化产生的硝酸盐中氧的来源。这些数据并未确定硝酸盐 - 硝酸盐氧交换是由亚硝酸氧化酶（H₂O + HNO₂→HNO₃ + 2H⁺ + 2e⁻）还是硝酸还原酶（HNO₃ + 2H⁺ + 2e⁻→HNO₂ + H₂O）或两种酶共同催化的。硝酸盐 - 硝酸盐交换反应表明存在一种利用H₂O的氧化还原酶的氧衍生物。
