Structure-based engineering of a NAD⁺-dependent secondary alcohol dehydrogenase from Micrococcus luteus led to a 1800-fold increase in catalytic efficiency for NADP⁺. Furthermore, the engineered enzymes (e.g., D37S/A38R/V39S/T15I) were successfully coupled to a NADPH-dependent Baeyer窶天illiger monooxygenase from Pseudomonas putida KT2440 for redox-neutral biotransformations of C18 fatty acids into C9 chemicals.