Effect of buffer carbonate and arsenate on the kinetics of glycation of human hemoglobin

Abstract

Abstract The glycation of hemoglobin is catalyzed by buffer carbonate and arsenate. The reaction of hemoglobin with glucose exhibits identical rates in protium and deuterium oxides, both for the buffer‐independent rate and for the first‐order rate in carbonate and arsenate buffer. When D ‐glucose‐2‐ h is compared with D ‐glucose‐2‐ d , the kinetic isotope effect for the buffer‐independent rates is ∼2, whereas the buffer‐dependent rate constants show no isotope effects. The absence of both substrate and solvent isotope effects for the buffer‐dependent term are indicative that a functional group on the hemoglobin is the proton‐abstracting base in the Amadori rearrangement. The catalytic constant ( k B ) of arsenate is double that of carbonate. A different base group on the hemoglobin may be involved in the abstraction of proton 2 in the Amadori rearrangement. Copyright © 2004 John Wiley & Sons, Ltd.