title: Apomyoglobin folding intermediates characterized by the hydrophobic fluorescent probe 8-anilino-1-naphthalene sulfonate.
abstract: Folding apomyoglobin intermediates were investigated by optical techniques including steady-state fluorescence, frequency domain fluorometry, and absorption spectroscopy. The investigated chromophores were the aromatic residues, i.e., tyrosyl and tryptophanyl residues, and the extrinsic probe (8-anilino-1-naphthalenesulfonate, ANS) which is particularly useful for studying partly structured forms appearing in the early stage of protein folding. The emission decay of the extrinsic probe as well as resonance energy transfer from tryptophanyl residues to ANS permitted to identify and characterize partly folded forms obtained under different experimental conditions. The results indicate that the intermediates so far detected (I-1 and I-2 states) are distinct structural states. The differences concern the solvent accessibility to the aromatic side chains and the conformational dynamics of the protein region forming the binding site for the extrinsic fluorophore.
authors.affiliation: Dipartimento di Biochimica e Biofisica, Seconda Università di Napoli, Via Costantinopoli 16, 80138 Napoli, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Sirangelo
authors.forename: E
authors.initials: E
authors.lastname: Bismuto
authors.forename: S
authors.initials: S
authors.lastname: Tavassi
authors.forename: G
authors.initials: G
authors.lastname: Irace
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D001059:Apoproteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D005456:Fluorescent Dyes / Q000378:metabolism; D006736:Horses; D006863:Hydrogen-Ion Concentration; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012997:Solvents; D013050:Spectrometry, Fluorescence
chemical_list: D000817:Anilino Naphthalenesulfonates; D001059:Apoproteins; D005456:Fluorescent Dyes; D009211:Myoglobin; D012997:Solvents; C010857:apomyoglobin; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate)