J. Biol. Chem., Vol. 261, Issue 15, 6758-6764, 05, 1986
Glycerated hemoglobin, alpha 2A beta 2(82) (EF6) N epsilon- glyceryllysine. A new post-translational modification occurring in erythrocyte bisphosphoglyceromutase deficiency
Y Blouquit, MD Rhoda, J Delanoe-Garin, R Rosa, JC Prome, C Poyart, G Puzo, JM Bernassau and J Rosa
A new minor Hb fraction initially designated Hbx, has been found in the
hemolysate of an erythremic patient that we have previously described with
a complete erythrocyte bisphosphoglycerate mutase (EC 5.4.2.4) deficiency.
Hbx (3.5% of the total) was detected by isoelectric focusing and exhibited
electrophoretic and chromatographic properties similar to those of several
variants of the Hb central cavity. By density fractionation of red cells,
it was demonstrated that Hbx was an aging hemoglobin as in the case of
glycated Hb A1c. Functional studies revealed a low oxygen affinity and
almost complete inhibition of the allosteric effect of the organic
phosphate effectors. Structural studies demonstrated an absence of tryptic
cleavage between the peptides beta T9 and beta T10 suggesting the presence
of an adduct on Lys beta 82 or on a neighboring residue. Fast atom
bombardment mass spectrometry and a specific enzymatic assay with
glyoxylate reductase demonstrated that the beta 82 adduct was a glycerate
moiety. It was concluded that Hbx was a glycerylated Hb, alpha 2A beta
2(82) (EF6) N epsilon-glyceryllysine, to our knowledge the first example of
glycerylated protein. The mechanism of formation of glyceryl Hb, which was
found in the four studied subjects with a bisphosphoglyceromutase
deficiency, remains to be determined.
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