Primary structure of human alpha 2-macroglobulin. III. Primary structure of three large disulfide-bridged CNBr fragments, located in the COOH-terminal part of alpha 2-macroglobulin and accounting for 301 residues.

The amino acid sequences have been determined for three CNBr fragments of human alpha 2-macroglobulin which form a disulfide-bridged Mr = 40,000 fragment set. The fragments are located in the COOH-terminal part of alpha 2-macroglobulin (CB18, residues 776-936; CB23, residues 1292-1355; and CB26, residues 1376-1451). CB18 contains one glucosamine-based carbohydrate group attached to Asn-71 and two internal disulfide bridges (Cys-23 bound to Cys-51 and Cys-49 bound to Cys-85, respectively). Cys-123 is disulfide bridged to Cys-7 of CB23. Cys-38 of CB23 is disulfide bridged to Cys-69 of CB26. CB26, which contains one glucosamine-based carbohydrate group attached to Asn-26, is the COOH-terminal CNBr fragment. CB18, CB23, and CB26 account for 301 of the 1451 residues of the subunit of alpha 2-macroglobulin.