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Amino acid sequence around the thiolester of α 2 ‐macroglobulin from plasma of the crayfish, Pacifastacus leniusculus
Author(s) -
Hall Martin,
Söderhäll Kenneth,
Sottrup-Jensen Lars
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81019-1
Subject(s) - pacifastacus , crayfish , chemistry , trypsin , size exclusion chromatography , methylamine , peptide sequence , alpha 2 macroglobulin , thiol , amino acid , macroglobulin , chromatography , biochemistry , biology , enzyme , ecology , gene
α 2 ‐Macroglobulin (α 2 M) was isolated from plasma of the freshwater crayfish, Pacifastacus leniusculus , using ultracentrifugation, ion‐exchange chromatography and gel filtration techniques. The Pacifastacus α 2 M molecule (Pα 2 M) was radioactively labeled in the thiol ester structure with iodo [ 14 C]acetic acid in the presence of methylamine. After reduction and carboxymethylation of the protein, it was digested with trypsin. A 14 C‐labeled tryptic peptide was sequenced and contained an amino acid sequence very similar to other known thiol ester sequences from human α 2 M and related proteins. The N‐terminal sequence of Pα 2 M was related to that recently determined for lobster α 2 M [(1987) J. Biol. Chem. 262, 14606–14611].