The relative extent of glycation of haemoglobin and albumin

The level of non-enzymatic glycation of a protein is thought to depend on the number of sites available for reaction, the half-life of the protein and the ambient concentration of glucose. Accordingly, the modification of two blood proteins with a similar number of potential sites but different survival times was examined in non-diabetic patients by periodate oxidation and by reduction with [3H]borohydride. The amount of glycation of haemoglobin and its sub-fractions HbA1 and HbA1c were determined to be 0.44, 2.42 and 2.24 mol/mol respectively and the corresponding value for albumin was 0.37 mol/mol protein. Amino acid analysis showed that the epsilon amino groups of albumin were more extensively modified than they were in haemoglobin and thus it is concluded that the average rate of reaction of the lysine residues in albumin is markedly faster than in haemoglobin.