2000 Volume 43 Issue 8 Pages 681-685
A hemoglobin specimen from a 46-year-old diabetic male was further analyzed because of an unexpectedly low HbA1c value in comparison to the plasma glucose level and the presence of an abnormal peak on an ionexchange high performance liquid chromatography (HPLC) test was noted.
An additional band was observed between the HbA and HbA2 bands on an isoelectrofocused polyacrylamide gel, suggesting the presence of a variant Hb. High-resolution ion-exchange HPLC using a Po1yCAT A, resin revealed the presence of an abnormal Hb and its glycated form. The glycation rate of the abnormal Hb was 10.4%, which is the same as that of normal HbA.This latter value was nearly equal to the immunoassay HbA1c value. Electrospray ionization mass spectrometry revealed the presence of a variant β chain, which was 58 Da less than the normal structure. Analysis of the cleaved globin using on-line HPLC/ESI/MS/MS to determine the sequence revealed a new substitution [β 52 (D 3) Asp→Gly]. This substitution was ascertained using protein and DNA sequencer analysis. We designated this variant as “Hb Hokusetsu”
Hb Hokusetsu exhibits normal stability during isopropanol tests and has no significant difference in oxygen affinity or cooperativity.
