Quantitation of glycosylated hemoglobin by boronate affinity chromatography

Total hemoglobin glycosylation and the contribution of glycosylation at the N-terminus of the beta-chains and at "non"-beta-N-terminal positions were quantitated by use of boronate affinity and ion exchange chromatography. Glycohemoglobin (y) was found to correlate linearly (y = 1.92x + 0.53; r = 0.96) with HbA1c (x) and to contain approximately 50% beta-N-terminally glycosylated hemoglobin. This result is in agreement with the binding on boronate agarose of the various hemoglobin components resolved by cation exchange chromatography. An amount of glycohemoglobin similar to that of HbA1c was isolatable from HbA. A slope of less than 2 results because HbA1c is retained only to 93% and the intercept of the regression line reflects the partial adherence (65%) of HbA1a + b to the resin. These results confirm the occurrence of significant "non"-beta-N-terminal glycosylation and show that under optimal chromatographic conditions total glycohemoglobin can be determined with boronate affinity chromatography.