Patent ID: 8796002

Claim:
An engineered ketoreductase polypeptide capable of converting (S)-tert-butyl 4-chloro-3-oxo-1-phenylbutan-2-ylcarbamate to tert-butyl (2S,3R)-4-chloro-3-hydroxy-1-phenylbutan-2-ylcarbamate with a relative activity at least 1.2-fold that of the polypeptide of SEQ ID NO:2, wherein the engineered ketoreductase polypeptide comprises an amino acid sequence at least 90% identical to SEQ ID NO:2 and includes one or more amino acid substitutions relative to SEQ ID NO: 2, selected from the group consisting of P2L; V28A; A34S; A47V; E50K; D81N; 590V; I191L; I91W; I91R; I91K; K94R; D112Y; G117D; S143R; V144T; G145A; R148H; A150G; F152L; N153G; N153V; N153H; T1585; G190A; S198N; I199M; I199L; I199N; M200I; A217T; I225V; P231F; A232V; E233Q; D244G; F260Y; and S261N.