Fluorescence of Tryptophan and Protein Dynamics

Gratton, Enrico; Silva, Norberto; Ferreira, Sérgio T.

doi:10.1007/978-94-009-3117-6_4

Cited by 2 publications

(5 citation statements)

References 23 publications

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“…In addition to the average lifetime, one can obtain extra information by the use of continuous lifetime distribution. As has been shown (Alcala et al , 1987a-c;Gratton et al, 1988), the width of the distribution is related to the distribution and dynamics of the interconverting substates responsible for the appearance of lifetime distribution. In our experiments the average lifetime calculated from double-exponential analysis proved to be identical in each case, with the value of the center of the continuous lifetime distribution within the limits of the experimental error (Table 1).…”

Section: Resultsmentioning

confidence: 69%

“…It seems to be unlikely that all of these investigated fluorophores have two different populations (different in fluorescence lifetime values); consequently, the case for the existence of two discrete components, which assumes two fluorophore populations, is not persuasive. To provide an alternative explanation of the heterogeneity of protein fluorescence, the distribution of fluorescence lifetime parameters was introduced (James and Ware, 1985;Engh et al, 1986;Alcala et al, 1987a-c;Gratton et al, 1988). It was shown that even if the physically veritable distribution is continuous, the analysis can still result in two or more discrete components (Demmer et al, 1987).…”

Section: Resultsmentioning

confidence: 99%

“….0 ( _ the width of the lifetime distribution: the change in the number of populated substates and in the interconversion rate between substates may alter the value of this parameter. The interconversion rate is assumed to be faster at higher temperature, which would result in smaller width (Gratton et al, 1988;Ferreira and Gratton, 1990;Ferreira et al, 1994). Therefore, the increasing width of the distribution with increasing temperature in the case of Mg-G-actin is probably due to the increase in the number of populated substates of the fluorophore.…”

Section: Resultsmentioning

confidence: 99%

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Spectroscopic study of conformational changes in subdomain 1 of G-actin: influence of divalent cations

Nyitrai¹,

Hild²,

Belágyi³

et al. 1997

Biophysical Journal

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Temperature dependence of the fluorescence intensity and anisotropy decay of N-(iodoacetyl)-N'-(5-sulfo-1-naphthyl)ethylenediamine attached to Cys374 of actin monomer was investigated to characterize conformational differences between Ca- and Mg-G-actin. The fluorescence lifetime is longer in Mg-G-actin than that in Ca-G-actin in the temperature range of 5-34 degrees C. The width of the lifetime distribution is smaller by 30% in Mg-saturated actin monomer at 5 degrees C, and the difference becomes negligible above 30 degrees C. The semiangle of the cone within which the fluorophore can rotate is larger in Ca-G-actin at all temperatures. Electron paramagnetic resonance measurements on maleimide spin-labeled (on Cys374) monomer actin gave evidence that exchange of Ca2+ for Mg2+ induced a rapid decrease in the mobility of the label immediately after the addition of Mg2+. These results suggest that the C-terminal region of the monomer becomes more rigid as a result of the replacement of Ca2+ by Mg2+. The change can be related to the difference between the polymerization abilities of the two forms of G-actin.

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Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Spectroscopic study of conformational changes in subdomain 1 of G-actin: influence of divalent cations

Nyitrai¹,

Hild²,

Belágyi³

et al. 1997

Biophysical Journal

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“…In this view, fluorescence lifetime distributions originate from the existence of multiple conformational substates of the protein, and distribution analysis of fluorescence decay data may provide information on the conformational landscape and enable detection of dynamics of the protein matrix on a picosecond/nanosecond time scale (Alcala et al, 1987a-c). The heterogeneity of the fluorescence decay (expressed as the width of the lifetime distribution) was shown to be related to microheterogeneity of trp environments arising from conformational dynamics of the protein (Alcala et al, 1987c; Gratton et al, 1988;Bismuto et al, 1988;Ferreira, 1989;Ferreira and Gratton, 1990; Rosato et al, 1990 a, b; Mei et al, 1992). All studies so far, however, have made use of tryptophan (trp) fluorescence.…”

Section: Introductionmentioning

confidence: 99%

“…(B) Temperature dependence of the width of the lifetime distribution.identical conditions (open circles). Activation energies of 4.2 and 7.4 kcal/mol were found for BSOD and L-tyr, respectively.The heterogeneity (width) of protein lifetime distributions has been related to the existence of conformational substates of the protein and to the rate of interconversion between them (Alcala et al, 1987 a-c;Gratton et al, 1988;Bismuto et al, 1988;Ferreira, 1989;Mei et al, 1992). We have therefore investigated the effects of different environmental conditions…”

mentioning

confidence: 99%

Conformational dynamics of bovine Cu, Zn superoxide dismutase revealed by time-resolved fluorescence spectroscopy of the single tyrosine residue

Ferreira

Stella

Gratton

1994

Biophysical Journal

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The structural dynamics of bovine erythrocyte Cu, Zn superoxide dismutase (BSOD) was studied by time-resolved fluorescence spectroscopy. BSOD is a homodimer containing a single tyrosine residue (and no tryptophan) per subunit. Frequency-domain fluorometry revealed a heterogeneous fluorescence decay that could be described with a Lorentzian distribution of lifetimes. The lifetime distribution parameters (center and width) were markedly dependent on temperature. The distribution center (average lifetime) displayed Arrhenius behavior with an Ea of 4.2 kcal/mol, in contrast with an Ea of 7.4 kcal/mol for the single-exponential decay of L-tyrosine. This indicated that thermal quenching of tyrosine emission was not solely responsible for the effect of temperature on the lifetimes of BSOD. The distribution width was broad (1 ns at 8 degrees C) and decreased significantly at higher temperatures. Furthermore, the width of the lifetime distribution increased in parallel to increasing viscosity of the medium. The combined effects of temperature and viscosity on the fluorescence decay suggest the existence of multiple conformational substrates in BSOD that interconvert during the excited-state lifetime. Denaturation of BSOD by guanidine hydrochloride produced an increase in the lifetime distribution width, indicating a larger number of conformations probed by the tyrosine residue in the denatured state. The rotational mobility of the tyrosine in BSOD was also investigated. Analysis of fluorescence anisotropy decay data enabled resolution of two rotational correlation times. One correlation time corresponded to a fast (picosecond) rotation that contributed 62% of the anisotropy decay and likely reported local mobility of the tyrosine ring. The longer correlation time was 50% of the expected value for rotation of the whole (dimeric) BSOD molecule and appeared to reflect segmental motions in the protein in addition to overall tumbling. Comparison between rotational correlation times and fluorescence lifetimes of BSOD indicates that the heterogeneity in lifetimes does not arise from mobility of the tyrosine per se, but rather from dynamics of the protein matrix surrounding this residue which affect its fluorescence decay.

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Fluorescence of Tryptophan and Protein Dynamics

Cited by 2 publications

References 23 publications

Spectroscopic study of conformational changes in subdomain 1 of G-actin: influence of divalent cations

Spectroscopic study of conformational changes in subdomain 1 of G-actin: influence of divalent cations

Conformational dynamics of bovine Cu, Zn superoxide dismutase revealed by time-resolved fluorescence spectroscopy of the single tyrosine residue

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