Acid glycohydrolase in Chinese hamster with spontaneous diabetes. I. Depressed levels of renal alpha-galactosidase and beta-galactosidase.

The activites of alpha-and Beta-galactosidases (alpha-D-galactoside galactohydrolase, EC 3.2.1.22; beta-D-galactoside galactohydrolase, EC 3.2.1.23) were significantly lower in the kidneys of diabetic XA line than those in the nondiabetic M line Chinese hamsters. The depression of these enzymes was found only in the kidney but not in liver, spleen, hind leg muscle, cheek pouch or spinal cord. In young XA animals before onset of glycosuria, renal alpha-galactosidase level was similar to that in age-matched M animals; whereas, their renal beta-galactosidase activity was about 90% of those in the M animals. Partial purification and separation of these enzymes were achieved by chromatography on DEAE-Sepharose CL-6B columns. beta-galactosidase was separated into two isozymes and depression of activity in the XA kidneys was evident in both. alpha-galactosidase was recovered in a single peak. The pH optima of these enzymes from XA and M animals were identical. With p-nitrophenyl glycosides as substrates, the Michaelis constants of these enzymes were also the same of XA and M animals. Molecular weight estimation by gel filtration on Sepharose 6B yielded similar results between M and XA samples: 2.4-10(5) for alpha-galactosidase and 1.6.10(5) and 1.9.10(5) for beta-galactosidase isozymes. The data suggest that the diabetic animals had lower concentrations of alpha-and beta-galactosidase in their kidneys, probably as a consequence of hyperglycemia.