Isolation and properties of goat β2-microglobulin

Abstract 1. 1. Goat β 2 - microglobulin was isolated and purified from colostrum. 2. 2. Comparisons of the amino acid composition and amino-terminal sequence the goat protein with the bovine and human homologues, indicates a high degree of similarity. Both goat and bovine β 2 - microglobulins differ slightly in composition from the human molecule, most notably in threonine and proline values. 3. 3. For the first 32 residues, bovine and goat differ only at two positions, one of which is a valyl/isoleucyl substitution consistent with the amino acid compositions. The equivalent goat/human sequence comparison shows seven differences. 4. 4. Immunological studies, using the ELISA method, also confirm the close relatedness of goat and bovine β 2 - microglobulin and their more distant relatedness to the human homologue.