Gorlatova N, Tchorzewski M, Kurihara T, Soda K, Esaki N
Institute for Chemical Research, Kyoto University, Japan.
Appl Environ Microbiol. 1998 Mar;64(3):1029-33. doi: 10.1128/AEM.64.3.1029-1033.1998.
A nitroalkane-oxidizing enzyme was purified to homogeneity from Neurospora crassa. The enzyme is composed of two subunits; the molecular weight of each subunit is approximately 40,000. The enzyme catalyzes the oxidation of nitroalkanes to produce the corresponding carbonyl compounds. It acts on 2-nitropropane better than on nitroethane and 1-nitropropane, and anionic forms of nitroalkanes are much better substrates than are neutral forms. The enzyme does not act on aromatic compounds. When the enzyme reaction was conducted in an 18O2 atmosphere with the anionic form of 2-nitropropane as the substrate, acetone (with a molecular mass of 60 Da) was produced. This indicates that the oxygen atom of acetone was derived from molecular oxygen, not from water; hence, the enzyme is an oxygenase. The reaction stoichiometry was 2CH3CH(NO2)CH3 + O2-->2CH3COCH3 + 2HNO2, which is identical to that of the reaction of 2-nitropropane dioxygenase from Hansenula mrakii. The reaction of the Neurospora enzyme was inhibited by superoxide anion scavengers in the same manner as that of the Hansenula enzyme. Both of these enzymes are flavoenzymes; however, the Neurospora enzyme contains flavin mononucleotide as a prosthetic group, whereas the Hansenula enzyme contains flavin adenine dinucleotide.
从粗糙脉孢菌中纯化出一种氧化硝基烷的酶，使其达到同质。该酶由两个亚基组成，每个亚基的分子量约为40,000。该酶催化硝基烷的氧化反应，生成相应的羰基化合物。它对2-硝基丙烷的作用比对硝基乙烷和1-硝基丙烷更好，且硝基烷的阴离子形式比中性形式是更好的底物。该酶不作用于芳香族化合物。当以2-硝基丙烷的阴离子形式为底物在18O2气氛中进行酶反应时，生成了丙酮（分子量为60 Da）。这表明丙酮的氧原子来源于分子氧，而非水；因此，该酶是一种加氧酶。反应化学计量式为2CH3CH(NO2)CH3 + O2→2CH3COCH3 + 2HNO2，这与马尔克汉逊酵母中2-硝基丙烷双加氧酶的反应相同。粗糙脉孢菌酶的反应与汉逊酵母酶的反应一样，受到超氧阴离子清除剂的抑制。这两种酶都是黄素酶；然而，粗糙脉孢菌酶含有黄素单核苷酸作为辅基，而汉逊酵母酶含有黄素腺嘌呤二核苷酸。
