The artificial alpha 1 beta 1-contact mutant hemoglobin, Hb Phe-35 beta, shows only small functional abnormalities

It was previously reported that Hb Philly with a mutation of Phe for Tyr at 35(C1)beta showed non-cooperative oxygen binding with a very high affinity and instability leading to hemolysis, Further, it lacked the H-1-NMR signa l at 13.1 ppm from 2,2-dimethyl-2-silapentane-5-sulfonate in normal hemoglo bin (Hb A), so that this signal was assigned to a hydrogen bond formed by T yr-35(C1)beta. Surprisingly, our artificial mutant hemoglobin with the same mutation as hb Philly showed slightly lowered oxygen affinity, almost norm al cooperativity, the H-1-NMR signal at 13.1 ppm and no sign of instability . Our results indicate that the mutation reported for Hb Philly and the ass ignment of the 13.1 ppm signal need reexamination. (C) 1998 Federation of E uropean Biochemical Societies.