Resolving the effects of albumin glycation using the quartz crystal microbalance

Pomona College, Chemistry Department, 645 N. College Avenue, Claremont, CA 91711, USA

^* e-mail: malkiat.johal@pomona.edu

Abstract

Both lysine and arginine residues are particularly important at receptor sites for binding anionic ligands. These receptor sites may become compromised via non-enzymatic glycation. While lysine residues are glycated in the presence of glucose, arginine residues are predominantly glycated by α-oxoaldehydes like glyoxal. This study used a quartz crystal microbalance with dissipation monitoring (QCM-D) to examine the binding affinity of surface immobilized human serum albumin (HSA) to hemin after the HSA was pre-incubated with glucose or glyoxal. We found it necessary to pre-expose the HSA functionalized crystal surface to hemin to block irreversible unintended interactions. Glycation with glucose showed little affect on HSA’s affinity for hemin, however, modification with glyoxal showed diminished hemin binding capacity. Despite the hemin-blocking step, we were unable to obtain K_d values consistent with those in literature, which we attribute to other unaccounted for nonspecific interactions. This study highlights the need for a kinetic QCM-D analysis method that accounts for unintended interactions at the sensor surface so that the hemin-blocking step may be eliminated.