Tryptophan phosphorescence has been used for over 20 years to study the conformation and flexibility of proteins under physiological conditions. The basis for this research has been the extraordinary sensitivity of the tryptophan triplet state to quenching by molecular collisions (protein flexibility). The triplet state photophysics of tryptophan and its analogs is inadequately understood; little is known of the actual physical mechanism by which collisions quench the triplet state and almost nothing is known about the triplet state photophysics and non-radiative decay of tryptophan analogs (which can be incorporated into proteins in vivo to generate spectrally enhanced proteins). This project will investigate the triplet state photophysics of trp and trp analogs at room temperature in glassy sugar matrixes and the effect of temperature and viscosity on these properties, additional studies will assay the effect of deuterium substitution on non-radiative decay of try ptophan to evaluate the influence of C-H stretch/bending modes on promoting the T to S transition. Measurements of quantum yields for fluorescence, triplet state formation, and phosphorescence will be combined with lifetime measurements to generate a complete photophysical characterization of the excited state photophysics of this important class of biological chromophores. Detailed comparison of the photophysical behavior in rigid (glassy sugar) and mobile (viscous solution) environments will allow evaluation of the quenching rate constant due to collisions for tryptophan and each of the analogs.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR001348-19
Application #
6328033
Study Section
Project Start
2000-08-01
Project End
2001-07-31
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
19
Fiscal Year
2000
Total Cost
$545
Indirect Cost
Name
University of Pennsylvania
Department
Type
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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