J. Biol. Chem., Vol. 261, Issue 15, 6811-6821, 05, 1986
Reaction of acetaldehyde with hemoglobin
RC San George and HD Hoberman
Acetaldehyde reacted with hemoglobin at neutral pH and 37 degrees C to form
adducts that were stable to dialysis and that were not reduced by sodium
borohydride. Hemoglobin tetramers having 2, 3, and probably 4 molar eq of
bound aldehyde were isolated by cation exchange chromatography. The sites
of attachment of the aldehyde were the free amino groups of the N-terminal
valine residues of the alpha and beta chains of hemoglobin. Derivatization
of the beta chains caused a greater increase in the acidity of the
hemoglobin than did derivatization of the alpha chains. Derivatization of
the beta chains was also preferred over that of the alpha chains.
Acetaldehyde derivatives of the N-terminal octapeptide of hemoglobin S
(beta sT-1 peptide), Val-Gly-Gly, and tetraglycine were formed readily,
contained 1 M eq of acetaldehyde/mol of peptide, and were not reduced by
sodium borohydride. In contrast, Ala-Pro-Gly failed to form a 1:1 adduct
with acetaldehyde. 13C NMR analysis of the peptide adducts formed with
[1,2- 13C]acetaldehyde indicated that tetrahedral diastereomeric
derivatives were produced. The 13C chemical shifts of the adducts formed
between hemoglobin and [1,2-13C]acetaldehyde were identical to those of the
peptide adducts although resonances from the individual diastereomeric
adducts at each hemoglobin site could not be resolved. The results cited
above as well as other evidence indicate that acetaldehyde reacts with the
amino termini of hemoglobin to form stable cyclic imidazolidinone
derivatives. An exchange of acetaldehyde residues between peptides was also
documented.