title: The role of Trp-82 in the folding of intestinal fatty acid binding protein.
abstract: Multiple phases have been observed during the folding and unfolding of intestinal fatty acid binding protein (WT-IFABP) by stopped-flow fluorescence. Site-directed mutagenesis has been used to examine the role of each of the two tryptophans of this protein in these processes. The unfolding and refolding kinetics of the mutant protein containing only tryptophan 82 (W6Y-IFABP) showed that the tryptophan at this location was critical to the fluorescence signal changes observed throughout the unfolding reaction and early in the refolding reaction. However, the kinetic patterns of the mutant protein containing only tryptophan 6 (W82Y-IFABP) indicated that the tryptophan at this location participated in the fluorescence signal changes observed early in the unfolding reaction and late in the refolding reaction. Together, these data suggest that native-like structure was formed first in the vicinity of tryptophan 82, near the center of the hydrophobic core of this beta-sheet protein, prior to formation of native-like structure in the periphery of the protein.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Dalessio
authors.forename: Susan E
authors.initials: SE
authors.lastname: Fromholt
authors.forename: Ira J
authors.initials: IJ
authors.lastname: Ropson
mesh_terms: D002942:Circular Dichroism; D050556:Fatty Acid-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014364:Tryptophan / Q000235:genetics / Q000378:metabolism*; D014508:Urea / Q000494:pharmacology
chemical_list: D050556:Fatty Acid-Binding Proteins; D014364:Tryptophan; D014508:Urea