Differences in aldehyde oxidase activity in cytosolic preparations of human and monkey liver

This study presents data showing individual differences in aldehyde oxidase activity in human and monkey liver cytosols. When assayed with benzaldehyde as a substrate, a significant inter-subject variation in the activity was found in the human liver preparations. When assayed with N1-methylnicotinamide as a substrate, the inter-subject variation of the activity was also observed, but to a lesser extent compared with that of the activity with benzaldehyde. Similarly, variations in aldehyde oxidase activity were found in the monkey liver preparations when assayed with benzaldehyde or N1-methylnicotinamide. The present study suggested that at least two isozymes of aldehyde oxidase exist in the human liver preparations.