title: Conformation of gramicidin-A in CTAB micellar media.
abstract: Gramicidin A (gA) is a linear pentadecapeptide, which exhibits various conformations depending on the environment. The conformational behavior of gA in spherical and rod-shaped cationic micelles formed by cetyltrimethylammonium bromide (CTAB) surfactant has been studied using circular dichroism (CD) and fluorescence spectroscopy, and a probable structure of gramicidin A in CTAB media has been proposed. A CD study shows that gramicidin A assumes beta(6.3) helical structure in cationic spherical as well as rod-shaped CTAB micellar media. Modeling studies show the flexibility of the side chain conformation particularly in tryptophan-9. Study of intrinsic fluorescence of tryptophans in gramicidin A indicates three distinct environments for the four-tryptophan residues in CTAB media.
authors.affiliation: Department of Chemistry, Indian Institute of Technology--Madras, Chennai 600 036, India.
authors.forename: J
authors.initials: J
authors.lastname: Shobini
authors.forename: A K
authors.initials: AK
authors.lastname: Mishra
authors.forename: Nagasuma
authors.initials: N
authors.lastname: Chandra
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D002942:Circular Dichroism; D006096:Gramicidin / Q000737:chemistry*; D008823:Micelles; D008958:Models, Molecular; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D002593:Cetrimonium Compounds; D008823:Micelles; D006096:Gramicidin; D000077286:Cetrimonium