Amino Acid Substitution in Hemoglobin M Akita

A new variant of Hb M was discovered from a family of hereditary cyanosis living in Akita by combined use of conventional tests for Hb M including spectroscopy of methemoglobin type hemolysate, agar gel electrophoresis (pH 7.0) and Amberlite IRC 50 chromatography. The hemoglobin was caued Hb M_Akita. MetHb M_Akita was purified by starch block electrophoresis (pH 7.0) of the metHb hemolysate of patient and deprived of heme to get M_Akita globin. Mixture of β chains (P^M+P^A) was also purified by CMC chromatography in 8M urea of the globin (Hb M_Akita + Hb A) prepared from the patient's hemolysate. The globin and the β chain mixture were aminoethylated, digested, with trypsin and then fingerprinted. The fingerprint thus made revealed abnormal spots related to peptides βTp-10, and βTp-10, 11. These were eluted, and hydrolyzed with hydrochloric acid. The amino acid analysis of the acid hydrolysate has demonstrated that, in Hb M_Akita, the ninety-second residue of the β chain, His (β 92), is substituted for by tyrosine. This hemoglobin is therefore expressed by the formula α_2β_2^92Tyr. Hb M_Akita is identical with Hb M_Hyde Park which was detected from a negro patient in the United States several months earlier.