sentences:  The reaction mechanism of aldose reductase in the direction of aldehyde reduction follows a sequential ordered path where NADPH binds, followed by the substrate.Binding of NADPH induces a conformational change (Enzyme•NADPH → Enzyme*•NADPH) that involves hinge-like movement of a surface loop (residues 213-217) so as to cover a portion of the NADPH in a manner similar to that of a safety belt.The alcohol product is formed via a transfer of the pro-R hydride of NADPH to the re face of the substrate's carbonyl carbon.