Evolution amino acid exchange

This study seems to suggest (but not to prove) that evolution of pronounced (R)-selectivity in the present case requires greater structural change than in the case of (5)-selectivity, which seems to be reflected in the comparatively high number of amino acid exchanges. However, the application of other strategies could lead to a different conclusion. It is also interesting that the amino acid substitutions described herein occur at positions quite different from the hot spots that were uncovered in the case of the (5)-selective mutants. 

S-product ent-40. As shown in Scheme 18, eight mutants, showing up to 54 % -selectivity and up to 79 % S-selectivity were sequenced. One further round of evolution, starting from the mutant shown in entry 3, led to an enzyme that had three additional amino acid exchanges and afforded an ee of the product 40 of 90%. 4-Methoxycyclohexanone was studied as substrate as well. Whereas the wild-type cyclohexanone monooxygenase affords... 

Ind. Vector = Indicator Vector Alph. = Alphabet AA = Amino Acid EG = Exchange Group HP = Hydrophobicity, NA = Nucleic Acid. The HP scale, alphabets, PAM substitution matrix, and evolution profile are as defined in Tables 6.1 and 6.2, and Figures 6.2 and 6.3, respectively. 

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