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首页> 外文期刊>Applied Microbiology and Biotechnology >Enzymatic (R)-phenylacetylcarbinol production in benzaldehyde emulsions
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Enzymatic (R)-phenylacetylcarbinol production in benzaldehyde emulsions

机译：苯甲醛乳液中的酶促（R）-苯基乙酰甲醇生产

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(R)-Phenylacetylcarbinol [(R)-PAC)] is the chiral precursor for the production of the pharmaceuticals ephedrine and pseudoephedrine. Reaction conditions were improved to achieve increased (R)-PAC levels in a simple batch biotransformation of benzaldehyde emulsions and pyruvate, using partially purified pyruvate decarboxylase (PDC) from the filamentous fungus Rhizopus javanicus NRRL 13161 as the catalyst. Lowering the temperature from 23degreesC to 6degreesC decreased initial rates but increased final (R)-PAC concentrations. Addition of ethanol, which increases benzaldehyde solubility, was not beneficial for (R)-PAC production. It was established that proton uptake during biotransformation increases the pH above 7 thereby limiting (R)-PAC production. For small-scale studies, biotransformations were buffered with 2-2.5 M MOPS (initial pH 6.5). High concentrations of MOPS as well as some alcohols and KCl stabilised PDC. A balance between PDC and substrate concentrations was determined with regards to (R)-PAC production and yields on enzyme and substrates. R. javanicus PDC (7.4 U/ml) produced 50.6 g/l (337 mM) (R)-PAC in 29 h at 6degreesC with initial 400 mM benzaldehyde and 600 mM pyruvate. Molar yields on consumed benzaldehyde and pyruvate were 97% and 59%, respectively, with 17% pyruvate degraded and 24% converted into acetaldehyde and acetoin; 43% PDC activity remained, indicating reasonable enzyme stability at high substrate and product concentrations. [References: 21]
机译：（R）-苯基乙酰基甲醇[[R-PAC]]是用于生产药物麻黄碱和伪麻黄碱的手性前体。使用来自丝状真菌爪哇根霉NRRL 13161的部分纯化的丙酮酸脱羧酶（PDC），通过简单的批量苯甲醛和丙酮酸的生物转化，改善了反应条件，以提高（R）-PAC水平。将温度从23℃降至6℃降低了初始速率，但增加了最终（R）-PAC浓度。添加乙醇会增加苯甲醛的溶解度，对（R）-PAC生产无益。已经确定，在生物转化过程中质子的吸收使pH增加到7以上，从而限制了（R）-PAC的产生。对于小规模研究，生物转化用2-2.5 M MOPS（初始pH 6.5）缓冲。高浓度的MOPS以及一些醇和KCl稳定了PDC。关于（R）-PAC的产生以及酶和底物的产率，确定了PDC和底物浓度之间的平衡。 Javanicus PDC（7.4 U / ml）在29°C的条件下于6小时内于29小时内产生50.6 g / l（337 mM）（R）-PAC，并带有初始400 mM苯甲醛和600 mM丙酮酸。消耗的苯甲醛和丙酮酸的摩尔产率分别为97％和59％，其中17％的丙酮酸降解，而24％的转化为乙醛和丙酮。保留了43％的PDC活性，表明在高底物和产物浓度下酶具有合理的稳定性。 [参考：21]

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