Two hemoglobin variants with an alteration of the oxygen-linked chloride binding: Hb antananarivo [α1(NA1)Val→Gly] and Hb barbizon [β144(HC1)Lys→Met]

Abstract

We here report two new, clinically silent, hemoglobin variants in which the structural modification disturbs the oxygen-linked chloride binding. Hb Antananarivo [α1(NA1)Val→Gly] was found during a systematic hematological study in a 24-year-old woman, who originates from Madagascar. Hb Barbizon [β144 (HC1)Lys→Met] was found in several members of a French family. The oxygen binding properties of Hb Barbizon were similar to those of Hb Antananarivo showing, in vitro, a decreased chloride effect as compared to Hb A. In Hb Barbizon, the replacement of lysine β 44 by a methionine residue decreased from 4 to 2 the excess positive charges in the central cavity, thus leading to a reduction of about half of the chloride effect. For Hb Antananarivo, the mechanism is unclear since there is no difference in the number of positive charges in the central cavity but alterations are likely at the aloc2 interface.

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Notes on contributors

C. Godart

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.