Picosecond fluorescence decay of lens protein gamma-II crystallin.
The fluorescence decay of tryptophan residues in the bovine lens protein gamma-II crystallin has been measured in aqueous buffer solutions. Results were obtained as a function of emission wavelength, temperature, dissolved oxygen, and denaturing solvent. The protein displayed complex fluorescence decay which fit a biexponential model with a long component (ns) and a short component (few hundred ps). Measured fluorescence quantum yields data for gamma-II crystallin allowed calculation of radiative and non-radiative rate constants. The radiative rate constant was consistent with that observed in other indole derivatives, while the non-radiative rate constant was quite large and accounted for the short lifetime in gamma-II. The temperature dependence of the non-radiative decay in gamma-II crystallin yielded a small activation energy of only 1-2 kcal/mol, compared to 4 kcal/mol for the reference compound NATA whose barrier is known to derive from the rotamer model.
Borkman
R F
RF
Institute for Molecular Science Myodaiji, Okazaki, Japan.
Douhal
A
A
Yoshihara
K
K
D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000737:chemistry*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D013696:Temperature
D003459:Crystallins