Cytidine-5'-monophosphate-N-acetylneuraminic acid. Asialoglycoprotein sialic acid transferase activity in liver and serum of patients with juvenile hepatic cirrhosis and alpha-1-antitrypsin deficiency.
The molecular basis for the accumulation of a substance which displays the immunological reactivity of alpha-1-antitrypsin within vesicles of liver parenchymal cells of individuals with hepatic cirrhosis and serum alpha-1-antitrypsin deficiency remains unclear. We recently reported that serum from a patient with alpha-1-antitrypsin deficiency and hepatic cirrhosis was substantially deficient in sialyltransferease (EC 2.4.99.1) an enzyme which transfers sialic acid from cytidine 5'-monophosphate-N-acetylneuraminic acid to a variety of asialoglycoprotein acceptors. In the present report we have extended these studies to include serum from five additional patients with alpha-1-antitrypsin deficiency and juvenile hepatic cirrhosis as well as a liver specimen obtained at autopsy of one of these patients. We find the sialytransferase activity in serum from six patients with alpha-1-antitrypsin deficiency and hepatic cirrhosis to be 50% of healthy pediatric control values and 30% of pediatric patients with liver disease. However, serum from family members homozygous for alpha-1-antitrypsin deficiency but without hepatic cirrhosis, and serum from patients with a variety of other kinds of liver disease, failed to exhibit the marked sialytransferase deficiency. Similar assays carried out on a homogenate of a liver sample from one patient with alpha-1-antitrypsin deficiency and hepatic cirrhosis indicated that the deficiency of sialyltransferase activity was not demonstrable in liver. Furthermore, a comparative kinetic analysis of serum and liver sialytransferase in normal and afflicted individuals failed to detect differences in substrate affinities which might account for a decrease in functional sialyltransferase capacity in individuals with alpha-1-antitrypsin deficiency and hepatic cirrhosis. These observations suggest that the serum sialyltransferase deficiency in such patients probably arises after chronic and extensive liver disease involving hepatic accumulation of alpha-1-antitrypsin rather than the enzyme deficiency being the primary cause of the hepatic cirrhosis and alpha-1-antitrypsin deficiency.
D000293:Adolescent; D000328:Adult; D002648:Child; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008103:Liver Cirrhosis / Q000201:enzymology*; D008107:Liver Diseases / Q000201:enzymology; D008297:Male; D012794:Sialic Acids / Q000378:metabolism*; D012799:Sialyltransferases / Q000172:deficiency / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism*; D019896:alpha 1-Antitrypsin Deficiency
D012794:Sialic Acids; D003569:Cytidine Monophosphate N-Acetylneuraminic Acid; D014166:Transferases; D012799:Sialyltransferases