TY - JOUR
T1 - Early intermediates in the photocycle of the Glu46Gln mutant of photoactive yellow protein
T2 - Femtosecond spectroscopy
AU - Devanathan, Savitha
AU - Lin, Su
AU - Cusanovich, Michael A.
AU - Woodbury, Neal
AU - Tollin, Gordon
N1 - Funding Information:
This work was supported in part by National Science Foundation grants MCB-9722781 and MCB-981788.
PY - 2000
Y1 - 2000
N2 - Transient absorption spectroscopy in the time range from -1 ps to 4 ns, and over the wavelength range from 420 to 550 nm, was applied to the Glu46Gln mutant of the photoactive yellow protein (PYP) from Ectothiorhodospira halophila. This has allowed us to elucidate the kinetic constants of excited state formation and decay and photochemical product formation, and the spectral characteristics of stimulated emission and the early photocycle intermediates. Both the quantum efficiency (~0.5) and the rate constants for excited state decay and the formation of the initial photochemical intermediate (I0) were found to be quite similar to those obtained for wild-type PYP. In contrast, the rate constants for the formation of the subsequent photocycle intermediates (I0(+) and I1), as well as for I2 and for ground state regeneration as determined in earlier studies, were found to be from 3- to 30-fold larger. The structural implications of these results are discussed.
AB - Transient absorption spectroscopy in the time range from -1 ps to 4 ns, and over the wavelength range from 420 to 550 nm, was applied to the Glu46Gln mutant of the photoactive yellow protein (PYP) from Ectothiorhodospira halophila. This has allowed us to elucidate the kinetic constants of excited state formation and decay and photochemical product formation, and the spectral characteristics of stimulated emission and the early photocycle intermediates. Both the quantum efficiency (~0.5) and the rate constants for excited state decay and the formation of the initial photochemical intermediate (I0) were found to be quite similar to those obtained for wild-type PYP. In contrast, the rate constants for the formation of the subsequent photocycle intermediates (I0(+) and I1), as well as for I2 and for ground state regeneration as determined in earlier studies, were found to be from 3- to 30-fold larger. The structural implications of these results are discussed.
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U2 - 10.1016/S0006-3495(00)76460-5
DO - 10.1016/S0006-3495(00)76460-5
M3 - Article
C2 - 11023916
AN - SCOPUS:0033798658
SN - 0006-3495
VL - 79
SP - 2132
EP - 2137
JO - Biophysical journal
JF - Biophysical journal
IS - 4
ER -