Decreased Benzoyl Formate Decarboxylation Activity of Variant

6 Decreased Benzoyl Formate Decarboxylation Activity of Variant 55E4 

Further studies, with the substrate ratio altered from 1 3 to 1 100, were performed in order to suppress the formation of benzoin 12 and increase the yield of DMA-HPP 10. Although this strategy was successful, the results showed that even a 100-fold excess of dimethoxyacetaldehyde 8 (500 mM) relative to benzaldehyde 4 (5 mM) could not completely supress benzoin 12 formation catalyzed by variant 55E4. Furthermore, the formation of the mixed product DMA-HPP 10 was decreased by a factor of 2 relative to the 1 3 substrate mixture. Variant 55 E4 showed a 55-fold higher productivity with respect to the formation of DMA-HPP 10 under these conditions as compared to variant L476Q. The overall carboligation 

L476Q catalyzed the substrate conversion to DMA-HPP 10 only at a neglegible rate. 

B) BFD variant 55E4 catalyzed the formation of both enantiomers of DMA-HPP 10 with retention times of approx. 15.1 min for the (S)- and approx. 16.4 min for the (R)-enantiomer. 

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