title: The reactive site of alpha 1-antitrypsin is C-terminal, not N-terminal.
abstract: alpha 1-Antitrypsin recovered from trypsin-alpha 1-antitrypsin complexes was shown to be a mixture of two peptides which remained associated in 6 M guanidine and in 1% acetic acid, but were separated by SDS-polyacrylamide gel electrophoresis. The larger peptide had an Mr of 47 000 and gave low yields on end-group analysis; the smaller had an Mr of 4000 and was the C-terminal 36-residue fragment of alpha 1-antitrypsin. These results explain the consistent but erroneous finding of a reactive site near the N-terminus of alpha 1-antitrypsin, and confirm that the reactive site is 36 residues from the C-terminus.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002852:Chromatography, Ion Exchange; D006801:Humans; D008970:Molecular Weight; D000515:alpha 1-Antitrypsin / Q000032:analysis*
chemical_list: D000596:Amino Acids; D000515:alpha 1-Antitrypsin