Scheme 2. Catalytic cycle for NADPH-dependent carbonyl reduction by Kvβ2.

Sequential binding of the protein to NADPH and the carbonyl substrate results in the formation of a ternary complex in which the carbonyl is reduced to its corresponding alcohol. The release of products is also shown to be ordered. The microscopic rate constants for each reaction step in the forward and reverse direction are indicated as k_n and k_−n, respectively.