Comparative biophysical characterization of chicken β2-microglobulin.
β(2)-microglobulin (β(2)m) is the smallest building block of molecules belonging to the immunoglobulin superfamily. By comparing thermodynamic and structural characteristics of chicken β(2)m with those of other species, we seek to elucidate whether it is possible to pinpoint features that set the avian protein apart from other β(2)m. The thermodynamic assays revealed that chicken β(2)m exhibits a lower melting temperature than human β(2)m, and the H/D exchange behavior observed by infrared spectroscopy indicates a more flexible structure of the former protein. To understand these differences at a molecular level, we determined the structure of free chicken β(2)m by X-ray crystallography to a resolution of 2.0 Å. Our comparisons indicate that certain biophysical characteristics of the chicken protein, particularly its conformational flexibility, diverge considerably from those of the other β(2)m analyzed, although basic structural features have been retained through evolution.
Institut für Immungenetik, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Freie Universität Berlin, Thielallee 73, 14195 Berlin, Germany.
Chee-Seng
CS
Hee
Heinz
H
Fabian
Barbara
B
Uchanska-Ziegler
Andreas
A
Ziegler
Bernhard
B
Loll
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002347:Carps; D002417:Cattle; D002645:Chickens; D018360:Crystallography, X-Ray; D041961:Deuterium Exchange Measurement; D006801:Humans; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D013816:Thermodynamics; D001613:beta 2-Microglobulin / Q000737:chemistry*
D021122:Protein Subunits; D001613:beta 2-Microglobulin