Nitromethane

• Published in: The Journal of biological chemistry 1972-03, Vol.247 (6), p.1951-1953
• Main Authors: Porter, David J.T., Voet, Judith G., Bright, Harold J.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)45562-2

d -Amino acid oxidase (EC 1.4.3.3) catalyzes the oxidation of nitromethane by O 2 in the presence or absence of light to give formaldehyde, nitrite, and H 2 O 2 as final products. The anaerobic reduction of the enzyme by nitromethane yields a species ( E' r ) the spectrum of which resembles, but is not identical with, that of free reduced enzyme. E' r reacts rapidly with O 2 to form fully oxidized enzyme. The enzyme remains in the oxidized state during turnover at pH 8.3 because the rate of oxidation of E' r by O 2 is 6 x 10 4 times faster than the rate of formation of E' r . The following scheme accommodates the observed kinetics of turnover and of the half-reactions. E o ( k 1 [CH 3 NO 2 ])/→ E'r (k 2 [O 2 ])/→ E o + H 2 O 2 Whether nitrite and formaldehyde (or a precursor such as HO—CH 2 —NO 2 ) are released in the first or second step has not been established. In addition to undergoing oxidative turnover, nitromethane slowly produces an irreversibly inactivated species of the enzyme with none of the spectral characteristics of oxidized enzyme. Nitromethane interacts with free FAD, but only in the presence of light, to give an oxidizable species having a spectrum resembling that of FADH 2 .