Effect of Nonenzymatic Glycosylation on the Magnetic Resonance Imaging (MRI) Contrast Agent Binding to Human Serum Albumin

Abstract

Enhanced nonenzymatic glycosylation (NEG) of human serum albumin (HSA) is observed in diabetic patients. This modifies some of the physiological functions of HSA, as the binding of ligands. Some gadolinium complexes, commonly used as MRI contrast agents, have a high affinity for HSA, which enhances their efficacy. The aim of this study is to evaluate the possible influence of the NEG of HSA on its affinity for some gadolinium chelates.

Zn2+‐Responsive Bimodal Magnetic Resonance Imaging and Fluorescence Imaging Agents and Their Interaction with Human Serum Albumin

“…To determine whether these Gd III complexes bind at site I (subdomain IIA) or site II (subdomain IIIA) of HSA, displacement experiments were performed with warfarin as a fluorescent probe for site I and l-tryptophan as a fluorescent probe for site II. [26] Upon binding to HSA, the fluorescence emission at 380 nm for warfarin or 365 nm for l-tryptophan is greatly enhanced ( Figure S5). Nevertheless, when the binding sites to HSA are occupied by other species, the fluorescence of the probes will be reduced.…”

“…The binding sites of HSA to the gadolinium(III) complexes were detected through displacement experiments with warfarin as a fluorescent probe for site I and l-tryptophan as a probe for site II. [26] Upon binding to HSA, the relaxivity (r 1 ) and the contrasts of T 1 -weighted phantom MR images for GdL1, (GdL1) 2 Zn, GdL1Zn, GdL2, and (GdL2) 2 Zn exhibit different degrees of enhancement. Interestingly, GdL1Zn displays the highest affinity towards HSA owing to the direct binding of HSA to Zn 2+ ions; both the relaxivity and the fluorescence of GdL1Zn exhibited threefold increases with an obvious blueshift of the emission in response to HSA.…”