title: Global analysis of the time-resolved fluorescence of alpha- chymotrypsinogen A and alpha-chymotrypsin powders as a function of hydration.
abstract: The time-resolved tryptophyl fluorescence of alpha-chymotrypsin A and alpha-chymotrypsin in the crystalline state and in buffer solution at room temperature was analyzed globally. Triple-exponential decay functions are necessary to adequately describe the tryptophyl fluorescence decay surfaces of the protein powders as a function of hydration and in solution. The fluorescence lifetimes of alpha-chymotrypsinogen A (tau 1 = 0.32, tau 2 = 1.30 ns, tau 3 = 3.98 ns) and alpha-chymotrypsin(tau 1 = 0.66 n s, tau 2 = 2.26 ns, tau 3 = 5.40 ns) are constant over the entire hydration range. The spectral positions of the decay-associated spectra of the hydrated powders do not shift as a function of hydration. This indicates that the structures of the zymogen and the active enzyme are unaffected by hydration. The lifetimes of alpha-chymotrypsinogen A in phosphate buffer pH 7.4 are tau 1 = 0.37 ns, tau 2 = 1.17 ns and tau 3 = 3.44 ns while the respective values of alpha-chymotrypsin are tau 1 = 0.47 ns, tau 2 = 1.40 and tau 1 = 3.89 ns.
authors.affiliation: Department of Chemistry, Katholieke Universiteit Leuven, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Vermunicht
authors.forename: N
authors.initials: N
authors.lastname: Boens
authors.forename: F C
authors.initials: FC
authors.lastname: de Schryver
mesh_terms: D002918:Chymotrypsin / Q000737:chemistry*; D002919:Chymotrypsinogen / Q000737:chemistry*; D003460:Crystallization; D007700:Kinetics; D013050:Spectrometry, Fluorescence / Q000379:methods; D014364:Tryptophan; D014867:Water
chemical_list: D014867:Water; D014364:Tryptophan; D002919:Chymotrypsinogen; D002918:Chymotrypsin