Subcellular distribution of oxidoreductases in genital organs of the male rat.

The subcellular distribution of alcohol and aldehyde-dehydrogenases in selected endocrine tissues of the adult male rat is reported. Certain kinetics and developmental aspects of these enzymes were also investigated. Aldehyde dehydrogenase (ALDH) was measurable in nuclear, mitochondrial, and cytoplasmic preparations of rat testis (T), ductus deferans (DD), and the penis (P). This enzyme was also present in nuclear and mitochondrial but not in cytoplasmic-fractions of the seminal vesicles (SV). Alcohol dehydrogenase (ADH) was measurable in cytoplasmic preparations of the rat testis, ductus deferans, and of the penis, in addition to that of the nuclear fraction of the rat testis. Testicular nuclear and mitochondrial-aldehyde dehydrogenase as well as cytoplasmic alcohol dehydrogenase increased as a function of age. The kinetics of the study indicate that nuclear ALDH in seminal vesicles possessed greater Vmax than corresponding ALDH in reproductive tissues studied. Mitochondrial ALDH of penis preparation showed a higher velocity of the enzymatic reaction than that assayed in T, DD, or SV-preparations, and these organs possessed similar Km. Testicular cytoplasmic ALDH displayed a marked high affinity towards the substrate, and DD-ALDH showed a similar Km to that of hepatic cytoplasmic ALDH. The Vmax of ADH determined in cytoplasmic fraction of the rat testis was greater than that assayed in the nuclear fraction with both preparations demonstrating equal Km value. The kinetics suggest that the velocity of the enzymatic reaction and the apparent Km values of these enzymes depends on the tissue and on the subcellular component fractionated.