Regulation Of Photosynthetic Coenzyme Regeneration Metabolism In Microalgae For Asymmetric Reduction Of Prochiral Carbonyl Compounds To Chiral Alcohols

Asymmetric reduction of prochiral carbonyl compounds by living cells is one ofthe most efficient and environmentally friendly methods to produce chiral alcohols. Theprocess requires coenzyme NAD(P)H as hydrogen donor. Then NAD(P)H is one of thekey factors that influence the efficiency of this asymmetric reduction. Microalgae cancatalyze prochiral carbonyl compounds to chiral alcohols, also it can efficientlyregenerate NADPH through photosynthesis at the same time. Discovering its catalyticproperties and developing an efficient catalytic process have important theoreticalsignificance and application value for bio-catalytic asymmetric synthesis. This thesisdiscovered the catalytic properties and the metabolism of photosynthetic coenzymeregeneration in microalgae for asymmetric reduction of prochiral carbonyl compoundsto chiral alcohols and further developed a metabolic regulating technology forphotosynthetic coenzyme regeneration to improve the efficiency of asymmetricreduction.First, the reaction characters were studied about asymmetric reduction of prochiralcarbonyl compounds to chiral alcohols by microalgae. It was found that Spirulinaplatensis could efficiently catalyze the asymmetric reduction of acetophenone toR-1-phenylethanol. As a result, the yield and enantiomeric excess were more than30%and99%, respectively. Scenedesmus obliquus could efficiently catalyze the asymmetricreduction of ethyl acetoacetate to ethyl3-hydroxybutyrate. As a result, the yield andenantiomeric excess were more than45%and65%, respectively.Then, we analyzed the metabolism of photosynthetic coenzyme regeneration anddeveloped a metabolic regulating technology for photosynthetic coenzyme regenerationin microalgae. There were two ways to regulate the metabolism of photosyntheticcoenzyme regeneration. At first, the coenzyme consumption was cutted by inhibitingglyceraldehyde3-phosphate dehydrogenase with inhibitors, such as iodoacetic acid, 4-chloromercuribenzoate and Angeli’ s Salt. It was found that NADPH in microalgaewere increased by71.9%,79.9%and96.0%, respectively. And the yield of theasymmetric redction reation were correspondingly improved by12.9%、10.2%and63.3%, respectively. On the other hand, the coenzyme regeneration was promoted byimproving electron transfer with sodium cholate, sodium acetate and sodium thiosulfate.The NADPH were correspondingly increased by73.1%,60.2%and70.4%, respectively.The yield were slso improved by118.4%、36.7%and26.2%, respectively.This work provides a direction for the metabolic regulation of coenzymeregeneration on asymmetric reduction of prochiral carbonyl compounds to chiralalachols by living cells, and also provides a theoretical basis for future in-depth studyon the mechanism of metabolic regulation of coenzyme regeneration.