title: Quenching of tryptophan fluorescence in various proteins by a series of small nickel complexes.
abstract: A series of twelve anionic, cationic, and neutral nickel(II) complexes have been synthesized and characterized. The interaction of these complexes with bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lyso), and tryptophan (Trp) has been studied using steady-state fluorescence spectroscopy. Dynamic and static quenching constants have been calculated, and the role played in quenching by the ligand and complex charge investigated. The nickel complexes showed selectivity towards the different proteins based on the environment surrounding the Trp residue(s). Only small neutral complexes with hydrophobic ligands effectively quenched protein fluorescence via static quenching, with association constants ranging from 10(2) M(-1) (free Trp) to 10(10) M(-1) (lysozyme), indicating a spontaneous and thermodynamically favorable interaction. The number of binding sites, on average, was determined to be one in BSA, HSA and free Trp, and two in lysozyme.
authors.affiliation: Department of Chemistry, Susquehanna University, Selinsgrove, PA 17870, USA.
authors.forename: Heather F
authors.initials: HF
authors.lastname: Crouse
authors.forename: Julianne
authors.initials: J
authors.lastname: Potoma
authors.forename: Farhat
authors.initials: F
authors.lastname: Nejrabi
authors.forename: Deanna L
authors.initials: DL
authors.lastname: Snyder
authors.forename: Balwant S
authors.initials: BS
authors.lastname: Chohan
authors.forename: Swarna
authors.initials: S
authors.lastname: Basu
mesh_terms: D001665:Binding Sites; D005453:Fluorescence; D057927:Hydrophobic and Hydrophilic Interactions; D009113:Muramidase / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D012709:Serum Albumin; D009532:Nickel; D014364:Tryptophan; D009113:Muramidase