HB hope, β136(H14)Gly→Asp, in a Diabetic Japanese Female and its Functional Characterization

Abstract

A β-variant hemoglobin, first misjudged as a marked elevation of Hb A₁, was found in a 68-year-old Japanese female with diabetes mellitus. This hemoglobin was isolated by Bio-Rex 70 chromatography combined with chromatofocusing, and was found to be Hb Hope, β136(H14)Gly→Asp, by classical and high performance liquid chromatographic peptide mapping techniques. Intrinsic oxygen affinity of this hemoglobin was approximately one-third as compared with that of Hb A_0. his property was still observed in the constituent β subunits isolated. Effects of such allosteric effectors as H⁺ (at a fixed concentration of Cl⁻), anion (Cl⁻), 2,3-diphosphoglycerate and carbon dioxide were more or less depressed. Among others, a marked reduction in the carbamate effect should be noted in a structural interpretation of the functional modifications. Subunit cooperatlvity, on the contrary, was not different from that in Hb A₀ (n = 2.8-2.9). Explanation of these altered functions were attempted on the basis of the altered structure. The reduced stability of Hb Hope is also described.