Pressure dependence of fluorescence quenching reactions in proteins
1988; Elsevier BV; Volume: 32; Issue: 1 Linguagem: Inglês
10.1016/0301-4622(88)85040-3
ISSN1873-4200
AutoresMaurice R. Eftink, Zygmunt Wasylewski,
Tópico(s)Photochemistry and Electron Transfer Studies
ResumoThe effect of hydrostatic pressure (0–2.6 kbar) on the acrylamide quenching of the fluorescence of indole derivatives and several single-tryptophan-containing proteins has been studied using phase fluorometry at 25°C. For the model system, N-acetyl-l-tryp-tophanamide in water, there is essentially no pressure dependence of the quenching rate constant, kq. For the internal Trp residue of ribonuclease T1 and cod parvalbumin, there also is essentially no pressure dependence of the apparent kq at low pressure. Thus, the activation volume, ΔV‡, for these quenching processes is approximately zero. Such small ΔV‡ values are expected for diffusion-limited reactions in water at this temperature. The low, apparent ΔV‡ values for the globular proteins characterize these quenching processes as involving very small amplitude fluctuations in the protein structures. Only for the poised tetramer ∡ monomer equilibrium of melittin were we able to observe a significant effect of pressure on kq and this is due to the pressure-induced shift in the equilibrium position.
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