Process for producing HMG-CoA reductase inhibitors

An isolated DNA which encodes for a polypeptide consisting of an amino acid sequence having at least 98% homology with the amino acid sequence of SEQ ID NO:

• 1, and having an activity of producing compound (II-a) or compound (II-b) from compound (I-a) or compound (I-b);
• wherein the compound (I-a) is a compound represented by the formula (I-a):
• the compound (I-b) is a lactone form of compound (I-a) and is represented by the formula (I-b):
• the compound (II-a) is a compound represented by the formula (II-a):
• the compound (II-b) is a lactone form of compound (II-a) and is represented by the formula (II-b):
• and wherein R1 represents a hydrogen atom, a substituted or unsubstituted alkyl, or an alkali metal, and R2 represents a substituted or unsubstituted alkyl, or a substituted or unsubstituted aryl.