Characterization and Properties of Hb York (β146 HIS-PRO)

Abstract

A 2nd case of Hb York (.beta.146 His .fwdarw. Pro), was discovered in a patient with polycythemia. The O2 equilibrium curves (OEC) of red cell suspensions in a buffer (pH 7.4) at 37.degree. C revealed a biphasic curve with a P50 [O2 partial pressure at 50% saturation of Hb] of only 12.5 mm Hg (normal value: 26.5 .+-. 1.0 mm Hg). The purified Hb York had an extremely high affinity for O2 with diminished cooperativity and decreased Bohr effect. The O2 affinity was significantly reduced by inositol hexaphosphate. Molecular stability studies by mechanical shaking of various liganded forms of Hb York revealed stabilities between those of Hb A and Hb S. Isolated .beta.Y-subunits were more unstable than .beta.A-subunits at every pH examined. Hb York was 1.4 times more unstable than Hb A in 18.9% isopropanol.