TY - GEN
T1 - Fluorescence of variant-3 scorpion neurotoxin
T2 - Time-Resolved Laser Spectroscopy in Biochemistry II
AU - Haydock, Christopher
AU - Sedarous, Salah S.
AU - Bajzer, Zeljko
AU - Prendergast, Franklyn G.
PY - 1990
Y1 - 1990
N2 - The fluorescence intensity decay of variant-3 scorpion nuerotoxin has an average lifetime of 510 picoseconds. The consensus of least squares, maximum likelihood, Pade-Laplace, and distributional analyses of this decay is that more than 90% of the initial intensity comes from short lifetime components with lifetimes in the range 0.05 to 0.5 nanoseconds and the remaining shall fraction of initial intensity is essentially one component decaying with an average lifetime of about 2 nanoseconds. Both adiabatic mapping and combined thermodynamic perturbation and umbrella sampling simulations reveal the presence of two tryptophan-47 rotational isomers. One of the isomers corresponds closely to the crystallographic structure and the second is a new rotational isomer that is separated from the first by a rotation angle of about 220 degrees and an activation barrier of about 10 kcal/mole. We propose that the short lifetime components corresponds to conformers with tryptophan-47 approximately in the crystallographic orientation and the long lifetime component is the new rotational isomer identified in the simulations.
AB - The fluorescence intensity decay of variant-3 scorpion nuerotoxin has an average lifetime of 510 picoseconds. The consensus of least squares, maximum likelihood, Pade-Laplace, and distributional analyses of this decay is that more than 90% of the initial intensity comes from short lifetime components with lifetimes in the range 0.05 to 0.5 nanoseconds and the remaining shall fraction of initial intensity is essentially one component decaying with an average lifetime of about 2 nanoseconds. Both adiabatic mapping and combined thermodynamic perturbation and umbrella sampling simulations reveal the presence of two tryptophan-47 rotational isomers. One of the isomers corresponds closely to the crystallographic structure and the second is a new rotational isomer that is separated from the first by a rotation angle of about 220 degrees and an activation barrier of about 10 kcal/mole. We propose that the short lifetime components corresponds to conformers with tryptophan-47 approximately in the crystallographic orientation and the long lifetime component is the new rotational isomer identified in the simulations.
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M3 - Conference contribution
AN - SCOPUS:0025607625
SN - 0819402451
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 92
EP - 99
BT - Proceedings of SPIE - The International Society for Optical Engineering
A2 - Lakowicz, Joseph F.
PB - Publ by Int Soc for Optical Engineering
Y2 - 15 January 1990 through 17 January 1990
ER -