Turkey beta 2-microglobulin--I. Isolation, properties and amino acid analysis

Turkey beta 2-microglobulin (beta 2m) was purified from pooled serum by successive steps of ultrafiltration, gel filtration chromatography, lectin affinity chromatography, anion exchange chromatography, isoelectric focusing and a second step of gel filtration. Identification of turkey beta 2m was based upon NH2-terminal primary structure analysis. The NH2-terminal primary structure of turkey beta 2m is: NH2-Lys-Ile-Glu-Val-Tyr-Ile-Lys-. The purity of the isolated protein was confirmed by two-dimensional polyacrylamide gel electrophoresis, immunodiffusion and immunoelectrophoresis. Physicochemical parameters of turkey beta 2m are: mol. wt, 10,500 (observed), 9959 (calculated); beta electrophoretic mobility; pI, 4.7, 5.2; E1%280, 10.9; absence of terminal D-mannopyranosyl and D-glucopyranosyl residues. Amino acid composition analysis demonstrated similarities between turkey and chicken beta 2ms that distinguished them from mammalian beta 2ms.