Reactivity of the amino groups of carbonmonoxyhemoglobin S with glyceraldehyde

The inhibition of erythrocyte sickling in vitro by glyceraldehyde has been shown previously to result from a reduced gelation of deoxyhemoglobin S. Accordingly, the sites of Schiff base formation of the sugar aldehyde with hemoglobin have been determined by peptide of the protein after treatment of CO-saturated sickle cells with 10 mM [14C]glyceraldehyde for 90 min and reduction with NaBH4. About 23% of the glyceraldehyde incorporated into hemoglobin was present at Val-1(beta) with very little present at Val-1(alpha) (less than 5%. The distribution of [14C]glyceraldehyde between the hemoglobin chains was 60% in the beta chains and 40% in the alpha chains. The reactive lysine residues of the beta chain were Lys-82, Lys-59, and Lys-120 (45%, 20%, and 16% of the total 14C in the beta chains, respectively). The most reactive lysine residue of the alpha chain was Lys-16 where 75% of the total [14C]glyceraldehyde was present. The limited number of sites reactive with glyceraldehyde indicate some type of selectivity in the reaction of sugar aldehydes with hemoglobin.