Binding mechanisms of PEGylated ligands reveal multiple effects of the PEG scaffold

Raibatak Das, Emily Baird, Scott Allen, Barbara Baird, David Holowka, Byron Goldstein

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

A series of synthetic ligands consisting of poly(ethylene glycol) (PEG), capped on one or both ends with the hapten 2,4-dinitrophenyl (DNP), were previously shown to be potent inhibitors of cellular activation in RBL mast cells stimulated by a multivalent antigen [Baird, E. J., Holowka, D., Coates, G. W., and Baird, B. (2003) Biochemistry 42, 12739-12748]. In this study, we systematically investigated the effect of increasing length of the PEG scaffold on the binding of these monovalent and bivalent ligands to anti-DNP IgE in solution. Our analysis reveals evidence for an energetically favorable interaction between two monovalent ligands bound to the same receptor, when the PEG molecular mass exceeds ∼5 kDa. Additionally, for ligands with much higher molecular masses (> 10 kDa PEG), the binding of a single ligand apparently leads to a steric exclusion of the second binding site by the bulky PEG scaffold. These results are further corroborated by data from an alternate fluorescence-based assay that we developed to quantify the capacity of these ligands to displace a small hapten bound to IgE. This new assay monitors the displacement of a small, receptor-bound hapten by a competitive monovalent ligand and thus quantifies the competitive inhibition offered by a monovalent ligand. We also show that, for bivalent ligands, inhibitory capacity is correlated with the capacity to form effective intramolecular cross-links with IgE.

Original languageEnglish (US)
Pages (from-to)1017-1030
Number of pages14
JournalBiochemistry
Volume47
Issue number3
DOIs
StatePublished - Jan 22 2008

ASJC Scopus subject areas

  • Biochemistry

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