Titration and exchange studies of liver fatty acid-binding protein with 13C-labeled long-chain fatty acids

Hsin Wang, Yan He, Christopher D. Kroenke, Sarala Kodukula, Judith Storch, Arthur G. Palmer, Ruth E. Stark

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Abstract

Uniformly 13C-labeled long-chain fatty acids were used to probe ligand binding to rat liver fatty acid-binding protein (LFABP), an atypical member of the fatty acid-binding protein (FABP) family that binds more than one molecule of long-chain fatty acid, accommodates a variety of diverse ligands, and exhibits diffusion-mediated lipid transport to membranes. Two sets of 1H-13C resonances were found in a titration series of NMR spectra for oleate-LFABP complexes, indicating that two molecules of the fatty acid are situated in the protein cavity. However, no distinct resonances were observed for the excess fatty acid in solution, suggesting that at least one ligand undergoes rapid exchange with oleate in the bulk solution. An exchange rate of 54 ± 6 s-1 between the two sets of resonances was measured directly using 13C z,z-exchange spectroscopy. In light of these NMR measurements, possible molecular mechanisms for the ligand-exchange process are evaluated and implications for the anomalous fatty acid transport mechanism of LFABP are discussed.

Original languageEnglish (US)
Pages (from-to)5453-5461
Number of pages9
JournalBiochemistry
Volume41
Issue number17
DOIs
StatePublished - Apr 30 2002

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ASJC Scopus subject areas

  • Biochemistry

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