title: The site of cleavage in human alpha chains of IgA1 and IgA2:A2m(1) allotype paraproteins by the clostridial IGA protease.
abstract: Fc fragments of human immunoglobulin A(IgA) of IgA1 subclass and IgA2 subclass of A2m(1) allotype were prepared from IgA paraproteins by digestion with a protease from Clostridium sp. (M.O.-6). The N-terminal tetrapeptide of Val-Pro-Ser-Thr- for the Fc of IgA1 subclass, and that of Val-Pro-Pro-Pro- for the Fc of IgA2:A2m(1) allotype, were identified by sequence analysis. The site of cleavage by the protease was defined to be at the Pro-Val peptide bond, which is a common peptide bond present at 221-222 in both alpha chains. IgA of IgA2 subclass of A2m(2) allotype is resistant to the protease due to the different, Arg-Val, peptide bond at the same position.
mesh_terms: D000595:Amino Acid Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D003013:Clostridium / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007122:Immunoelectrophoresis; D007070:Immunoglobulin A; D007141:Immunoglobulin Fc Fragments; D007143:Immunoglobulin Heavy Chains; D007137:Immunoglobulin alpha-Chains; D010266:Paraproteins / Q000276:immunology*; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases
chemical_list: D007070:Immunoglobulin A; D007141:Immunoglobulin Fc Fragments; D007143:Immunoglobulin Heavy Chains; D007137:Immunoglobulin alpha-Chains; D010266:Paraproteins; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase