Hyperunstable Hemoglobin Toyama [α₂136(H19)LEU→ARGβ₂]: Detection and Identification by in Vitro Biosynthesis with Radioactive Amino Acids

Abstract

A previously reported case of congenital Heinz body anemia was reinvestigated. Heat denaturation, isopropanol testing, PCMB precipitation, isoelectricfocusing, and reversed phase high performance liquid chromatography on the red cell lysate from the patient gave either negative, or at most, questionable results. In vitro globin biosynthesis using peripheral blood with incorporation of ³H-leucine demonstrated the production of an abnormal a chain at the rate of about 1/3 that of the normal a chain. A substitution, α136(H19)Leu→Arg, was elucidated by peptide mapping and radiose-quencing of an abnormal tryptic peptide.

The hemoglobin consisting of the abnormal o and normal β chains eluted between Hb A₂ and Hb A₀ in anion exchange high performance liquid chromatography. It was barely detectable by this method, comprising less than 1/1000 of the amount of Hb A₀, although it was produced at a level of 1/3 of that of Hb A₀ in terms of radioactivity.

The daughter of the propositus was similarly afflicted and produced the same abnormal a chain. The son, who also produced the abnormal o chain, was essentially free from hemolytic manifestation. His red cells were microcytic and showed an α/β synthetic ratio of over 2.