title: Parvalbumin conformers revealed by steady-state and time-resolved fluorescence spectroscopy.
abstract: The binding of calcium to whiting (one tryptophan residue) and pike (one tyrosine residue) parvalbumins has been studied by means of kinetic and steady-state fluorescence techniques. The decay curves of the tryptophan and tyrosine fluorescence of the parvalbumins are best fitted by a sum of two exponents for any metal state of the proteins. The data can be interpreted as a nonexponential decay of the fluorescence of a single-type chromophore or in terms of equilibria between compact and relaxed conformers of the parvalbumins in each metal state. Fluorescence quenching by I-ions and effects of H2O/D2O substitution confirm the second interpretation. The constants of the equilibria have been evaluated.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid; D005399:Fishes / Q000378:metabolism*; D007455:Iodine; D007526:Isoelectric Point; D007700:Kinetics; D008433:Mathematics; D009124:Muscle Proteins / Q000378:metabolism*; D010320:Parvalbumins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D009124:Muscle Proteins; D010320:Parvalbumins; D004533:Egtazic Acid; D007455:Iodine; D002118:Calcium