Evaluating Ketoreductase Exchanges as a Means of Rationally Altering Polyketide Stereochemistry.Modular polyketide synthases (PKSs) are multidomain multienzymes responsible for the biosynthesis in bacteria of a wide range of polyketide secondary metabolites of clinical value.  The exchange of ketoreductase (KR) domains in model PKSs has been shown in several cases to predictably alter the configuration of the β-hydroxy functionalities but not of the α-methyl groups. 
PKSs
By systematic screening of a broad panel of KR domains, we have identified two donor KRs that afford modification of α-methyl group stereochemistry. 
KR domains
Evaluating Ketoreductase Exchanges as a Means of Rationally Altering Polyketide Stereochemistry.Modular polyketide synthases (PKSs) are multidomain multienzymes responsible for the biosynthesis in bacteria of a wide range of polyketide secondary metabolites of clinical value.  The exchange of ketoreductase (KR) domains in model PKSs has been shown in several cases to predictably alter the configuration of the β-hydroxy functionalities but not of the α-methyl groups. 
PKSs