title: Monitoring membrane protein conformational heterogeneity by fluorescence lifetime distribution analysis using the maximum entropy method.
abstract: Due to the inherent difficulty in crystallizing membrane proteins, approaches based on fluorescence spectroscopy have proved useful in elucidating their conformational characteristics. The ion channel peptide gramicidin serves as an excellent prototype for monitoring membrane protein conformation and dynamics due to a number of reasons. We have analyzed conformational heterogeneity in membrane-bound gramicidin using fluorescence lifetime distribution analysis of tryptophan residues by the maximum entropy method (MEM). MEM represents a model-free and robust approach for analyzing fluorescence lifetime distribution. In this paper, we show for the first time, that fluorescence lifetime distribution analysis using MEM could be a convenient approach to monitor conformational heterogeneity in membrane-bound gramicidin in particular and membrane proteins in general. Lifetime distribution analysis by MEM therefore provides a novel window to monitor conformational transitions in membrane proteins.
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad, 500 007, India.
authors.forename: Sourav
authors.initials: S
authors.lastname: Haldar
authors.forename: Mamata
authors.initials: M
authors.lastname: Kombrabail
authors.forename: G
authors.initials: G
authors.lastname: Krishnamoorthy
authors.forename: Amitabha
authors.initials: A
authors.lastname: Chattopadhyay
mesh_terms: D001407:Bacillus; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D019277:Entropy; D006096:Gramicidin / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D014364:Tryptophan
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D006096:Gramicidin; D014364:Tryptophan