手性环氧氯丙烷的CPO酶催化不对称合成

基于氯过氧化物酶(CPO)对有机底物的手性识别,以CPO催化、叔丁基过氧化氢(TBHP)氧化3-氯丙烯合成手性(R)-环氧氯丙烷,并引入多羟基化合物为添加剂提高了目标产物的产率及对映选择性.反应主要受体系的pH值以及CPO用量等因素控制.UV-vis及CD光谱分析表明,反应体系中引入多羟基化合物(甘油、PEG400、PEG600)时,CPO的血红素辅基暴露程度增加,底物容易接近活性中心,同时CPO的α-螺旋结构得以加强,从而有效提高了产物收率.CPO对底物的手性识别主要基于底物与酶催化中间体([Fe(IV)=O·]+)形成的复合物对酶的稳定性的影响.通过反应条件优化,(R)-环氧氯丙烷产率可达67.3%,对映选择性(ee)97.5%.

Asymmetry synthesis of chiral epichlorohydrin catalyzed by chloroperoxidase

Asymmetric epoxidation of 3-chloropropene can be catalyzed by chloroperoxidase （CPO） from Caldariomyces fumago to produce （R）-epichlorohydrin （ECH） using t-butyl hydroperoxide （TBHP） as oxidant in phrosphate buffer with polyhydroxy compounds as additives at 25 ℃. The reaction was controlled by pH and CPO consumption. UV-vis and CD spectrum assay indicated that the introduction of glycerin,PEG 400 and PEG 600 would intensify the exposure of heme,which made it easier for CPO to bind with the substrate. Moreover,the alpha-helix structure of CPO was improved,which was also favourable for CPO activity and stability. The chiral recognition of CPO to substrate was based on the effect of substrate-compound （[Fe（IV）=O·]＋） complex on CPO stability. Compared with hydrolytic kinetic resolution using chiral salen,（R）-ECH yield reached 67.3% in 1 h with high enantiomeric excesses （ee 97.5%） catalyzed by CPO with polyhydroxy compounds as additives at optimum condition. CPO consumption was very small,which suggested that it is a practical method for industrial purpose.