Characterization and properties of Hb York (beta 146 His leads to Pro)

A second case of Hb York (beta 146 His leads to Pro), was discovered in a patient with polycythemia. The oxygen equilibrium curves (OEC) of red cell suspensions in a buffer (pH 7.4) at 37 degrees C revealed a biphasic curve with a P50 of only 12.5 mm Hg (normal value: 26.5 +/- 1.0 mm Hg). The purified Hb York had an extremely high affinity for oxygen with diminished cooperativity and decreased Bohr effect. The oxygen 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.