title: The effect of neuraminidase on genetic variants of alpha anitrypsin.
abstract: Sera of Pi types M, F, S, Z, IM, FM, MS, and MZ were incubated with neuraminidase and the reaction products followed by electrophoresis. The alpha1 antitrypsin components showed a series of changes in mobility as sialic residues were removed. Removal of sialic acid was confirmed by chemical assay. Results of studies with two different electrophoretic systems suggested that the Z type alpha1 antitrypsin has less sialic acid than the M, F, and S types. There was no evidence that other genetic variants have a reduced sialic acid content. The two major bands of alpha1 antitrypsin seen in certain electrophoretic systems may reflect a difference of one sialic acid residue. It is proposed that the Z protein lacks a carbohydrate chain with two terminal sialic acid residues. This carbohydrate deficiency results in lack of secretion of type Z alpha1 antitrypsin from the endoplasmic reticulum, perhaps because of binding to sites specific for the incomplete glycoprotein or because of aggregation of the Z asialo protein. A carbohydrate chain could be prevented from attaching to the Z type either because of a conformational change or because of the replacement of a carbohydrate-binding asparagine residue in the Z protein.
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001216:Asparagine / Q000032:analysis; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D004592:Electrophoresis, Starch Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D014644:Genetic Variation; D006579:Heterozygote; D006801:Humans; D007122:Immunoelectrophoresis; D066298:In Vitro Techniques; D009439:Neuraminidase / Q000494:pharmacology*; D012794:Sialic Acids / Q000032:analysis; D000515:alpha 1-Antitrypsin / Q000032:analysis
chemical_list: D012794:Sialic Acids; D000515:alpha 1-Antitrypsin; D001216:Asparagine; D009439:Neuraminidase