FT-IR STUDY ON THERMAL-DENATURATION PROCESSES OF OVOMACROGLOBULIN ANDALPHA(2)-MACROGLOBULIN

Thermal denaturation processes of chicken egg white ovomacrogrobulin a nd human serum alpha(2)-macroglobulin with and without chymotrypsin ha ve been studied in H2O and D2O solutions. Denaturation temperatures of ovomacroglobulin and alpha(2)-macroglobulin are 60 degrees C and 66 d egrees C, respectively. The deconvolved amide I and I' bands assignabl e to the beta-sheet structure show distinct downshifts at the denatura tion temperatures. The downshifts are attributed to the formation of a n intermolecularly hydrogen-bonded beta-sheet structure between separa ted half macroglobulin molecules. The denaturation temperatures rise m ore than 10 degrees C by the chymotrypsin binding to ovomacroglobulin or alpha(2)-macroglobulin. The denaturation temperature of methylamine -treated alpha(2)-macroglobulin is not different from that of native a lpha(2)-macroglobulin.