Dipeptidyl aminopeptidase IV in hospitalized patients and in galactosamine hepatitis of the rat: Activity and lectin affinity chromatography in serum and hepatic plasma membranes
Eggstein, S.; Kreisel, W.; Gerok, W.; Eggstein, M.
Journal of Clinical Chemistry and Clinical Biochemistry 27(9): 547-554
1989
ISSN/ISBN: 0340-076X PMID: 2575117 Document Number: 341537
The activity of dipeptidyl aminopeptidase IV was studied in the sera of 378 hospitalized patients. The mean activity of dipeptidyl aminopeptide IV was elevated significantly in patients with neoplasmata and hepatitis, but not in patients with liver cirrhosis. Significant correlations (p < 0.001) existed with .gamma.-glutamyl transferase, glutamate dehydrogenase, alkaline phosphatase and leucine aminopeptidase. A significant correlation with lactate dehydrogenase existed only in patients with neoplasmata. Principal component analysis, performed with aspartate aminotransferase, alanine aminotranferase, alkaline phosphatase, leucine aminopeptidase, lactate dehydrogenase and dipeptidyl aminopeptidase IV, revealed correlations between the activities of aspartate aminotransferase and alanine aminotransferase, and between alkaline phosphatase and leucine aminopeptidase, but neither dipeptidyl aminopeptidase IV nor lactate dehydrogenase showed any correlation with either of these two groups. In lectin affinity chromatography with concanavalin A and wheat germ lectin sepharose, serum dipeptidyl aminopeptidase IV from liver cirrhosis patients showed the same binding pattern as that from healthy subjects. The activity and glycosylation of dipeptidyl aminopeptidase IV in serum and hepatic plasma membranes was investigated in rats, following the induction of hepatitis with galactosamine. In the serum, dipeptidyl aminopeptidase IV activity was elevated as early as 6 h after galactosamine injection, and the elevated activity persisted until the 7th day. At the same time dipeptidyl aminopeptidase IV activity was also elevated in the hepatic plasma membrane. Ninety eight percent of hepatic dipeptidyl aminopeptidase IV bound to concanavalin A as well as to wheat germ lectin and this value was unchanged during hepatitis. In the serum of control rats, 90% of dipeptidyl aminopeptidase IV bound to concanavalin A but only 39% to wheat germ lectin. During galactosamine hepatitis, the wheat germ lectin binding fraction of serum dipeptidyl aminopeptidase IV increased significantly (p < 0.001) from 39% to 59%. We suggest that the increased levels of dipeptidyl aminopeptidase IV in serum are derived from the hepatic plasma membrane, where dipeptidyl aminopeptidase IV accumulates during hepatitis.