Isoenzymes of four acid hydrolases in human kidney and urine

The occurrence of different isoenzymes of β-glucosidase, β-glucuronidase, N-acetyl-β-glucosaminidase, and α-mannosidase in human urine and kidney tissue was studied by isoelectric focusing. Artificial substrates were used for the enzymatic assays. There was a predominance of isoenzymes with a low isoelectric point in the urine. In the kidney tissue isoenzymes with higher isoelectric point predominated. This difference may be due to a higher proportion of N-acetylneuraminic acid-containing enzymes in the urine than in the kidney tissue.