Enzymatic reduction of phenylglyoxal and 2,3-butanedione, two commonly used arginine-modifying reagents, by the ketoacyl reductase domain of fatty acid synthase.

Fatty acid synthase catalyzes the reduction of one of the carbonyl groups in phenylglyoxal and 2,3-butanedione using NADPH as the reductant. Selective inactivation of the enoyl reductase, one of the two reductase domains that could catalyze this reduction, did not affect the carbonyl reduction showing that the ketoreductase domain catalyzed the reaction. The apparent Km for the two arginine-specific reagents were lower than that for 3-acetoacetyl-N-acetyl cysteamine, the commonly used model substrate for the ketoreductase activity of the synthase.