Shoji Osami, Watanabe Yoshihito
Bioinorganic Chemistry Laboratory, Department of Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan,
Adv Exp Med Biol. 2015;851:189-208. doi: 10.1007/978-3-319-16009-2_7.
Cytochrome P450s (P450s) catalyze the NAD(P)H/O2-dependent monooxygenation of less reactive organic molecules under mild conditions. The catalytic activity of bacterial P450s is very high compared with P450s isolated from animals and plants, and the substrate specificity of bacterial P450s is also very high. Accordingly, their catalytic activities toward nonnative substrates are generally low especially toward small hydrocarbons. However, mutagenesis approaches have been very successful for engineering bacterial P450s for the hydroxylation of small hydrocarbons. On the other hand, "decoy" molecules, whose structures are very similar to natural substrates, can be used to trick the substrate recognition of bacterial P450s, allowing the P450s to catalyze oxidation reactions of nonnative substrates without any substitution of amino acid residues in the presence of decoy molecules. Thus, the hydroxylation of small hydrocarbons such as ethane, propane, butane and benzene can be catalyzed by P450BM3, a long-alkyl-chain hydroxylase, using substrate misrecognition of P450s induced by decoy molecules. Furthermore, a number of H2O2-dependent bacterial P450s can catalyze the peroxygenation of a variety of nonnative substrates through a simple substrate-misrecognition trick, in which catalytic activities and enantioselectivity are dependent on the structure of decoy molecules.
细胞色素P450（P450s）在温和条件下催化NAD(P)H/O₂依赖的低反应性有机分子单加氧反应。与从动物和植物中分离出的P450s相比，细菌P450s的催化活性非常高，并且细菌P450s的底物特异性也非常高。因此，它们对非天然底物的催化活性通常较低，尤其是对小分子烃类。然而，诱变方法在改造细菌P450s以实现小分子烃类羟基化方面非常成功。另一方面，结构与天然底物非常相似的“诱饵”分子可用于欺骗细菌P450s的底物识别，使P450s在存在诱饵分子的情况下无需任何氨基酸残基取代就能催化非天然底物的氧化反应。因此，长链烷基羟化酶P450BM3可以利用诱饵分子诱导的P450s底物误识别来催化乙烷、丙烷、丁烷和苯等小分子烃类的羟基化反应。此外，许多依赖H₂O₂的细菌P450s可以通过一种简单的底物误识别技巧催化多种非天然底物的过氧化反应，其中催化活性和对映选择性取决于诱饵分子的结构。
