Structural determination of a new electrophoreticaly silent variant: hemoglobin Alzette, beta 104(G6)Arg --> Lys.

A new electrophoreticaly neutral hemoglobin variant was found by ion-exchange high-performance liquid chromatography (HPLC). The molecular mass of the β-chain was shifted down 28 mass units. The modification was found in the βT-11 peptide that co-elutes with βT-14 in the tryptic HPLC profile. Collision-induced decomposition of the protonated modified peptide indicated the Arg → Lys exchange at the C-terminus. This modifies the fragmentation pattern as charge-remote processes induced by the strong basicity of arginine were replaced by charge-induced mechanisms. The exchanged 104 Arg is one of the chloride binding sites in the central cavity of Hb.