Binding properties of Echinococcus granulosus fatty acid binding protein

EgFABP1 is a developmentally regulated intracellular fatty acid binding pro tein characterized in the larval stage of parasitic platyhelminth Echinococ cus granulosus. It is structurally related to the heart group of fatty acid binding proteins (H-FABPs). Binding properties and ligand affinity of reco mbinant EgFABP1 were determined by fluorescence spectroscopy using cis- and trans-parinaric acid. Two binding sites for cis- and trans-parinaric acid were found (K-d(1) 24 +/- 4 nM, K-d(2) 510 +/- 60 nM for cis-parinaric acid and K-d(1) 32 +/- 4 nM, K-d(2) 364 +/- 75 nM for trans-parinaric). A putat ive third site for both fatty acids is discussed. Binding preferences were determined using displacement assays. Arachidonic and oleic acids presented the highest displacement percentages for EgFABP1. The Echinococcus FABP is the unique member of the H-FABP group able to bind two long chain fatty ac id molecules with high affinity. Structure-function relationships and putat ive roles for EgFABP1 in E. granulosus metabolism are discussed. (C) 2001 E lsevier Science B.V. All rights reserved.