The artificial α1β1-contact mutant hemoglobin, Hb Phe-35β, shows only small functional abnormalities

AbstractIt was previously reported that Hb Philly with a mutation of Phe for Tyr at 35(C1)β showed non-cooperative oxygen binding with a very high affinity and instability leading to hemolysis. Further, it lacked the 1H-NMR signal at 13.1 ppm from 2,2-dimethyl-2-silapentane-5-sulfonate in normal hemoglobin (Hb A), so that this signal was assigned to a hydrogen bond formed by Tyr-35(C1)β. Surprisingly, our artificial mutant hemoglobin with the same mutation as Hb Philly showed slightly lowered oxygen affinity, almost normal cooperativity, the 1H-NMR signal at 13.1 ppm and no sign of instability. Our results indicate that the mutation reported for Hb Philly and the assignment of the 13.1 ppm signal need reexamination