Enzymatic activity of atypical oriental types of aldehyde dehydrogenases

Catalytic activity of the atypical Oriental-type aldehyde dehydrogenase-2 (ALDH₂) was considered to be null or severely diminished. Recently it was suggested that the atypical ALDH ₂ ² retained about 30% of the specific activity of the usual ALDH ₂ ¹ . We reexamined the problem by two-dimensional crossed immunoelectrophoresis. The usual Caucasian livers exhibited two distinctive precipitin peaks, one corresponding to the cytosolic ALDH₁ and the other corresponding to the usual mitochondrial ALDH ₂ ¹ , in both protein stain and enzyme activity stain. In contrast, the atypical Oriental livers exhibited two precipitin peaks in protein stain, but only one peak, corresponding to ALDH₁, in enzyme activity stain. These results support the original notion that the atypical ALDH ₂ ² is enzymatically inactive or far less active than the usual enzyme, refuting the idea of the atypical ALDH ₂ ² with substantial enzyme activity.This work was supported by U.S. Public Health Service Grants HL-29515 and AA05763.