Excited-state lifetime studies of the three tryptophan residues in the N-lobe of human serum transferrin.

ABSTRACT: The energy transfer from the three Trp residues at positions 8, 128, and 264 within the human serum transferrin (hTF) N-lobe to the ligand to metal charge transfer band has been investigated by monitoring changes in Trp fluorescence emission and lifetimes. The fluorescence emission from hTF N-lobe is dominated by Trp264, as revealed by an 82% decrease in the quantum yield when this Trp residue is absent. Fluorescence lifetimes were determined by multifrequency phase fluorometry of mutants containing one or two Trp residues. Decays of these samples are best described by two or three discrete lifetimes or by a unimodal Lorentzian distribution. The discrete lifetimes and the center of the lifetime distribution for samples containing Trp128 and Trp264 are affected by iron. The distribution wid

SUBMITTER: James NG 

PROVIDER: S-EPMC2817844 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature