We have constructed (and continue to develop) a laser-based facility for time-resolved fluorescence spectroscopy of biomolecules. This facility provides rapid collection and analysis of luminescence data related to macromolecular size, flexibility, folding and structural fluctuations. Our time-correlated laser fluorometer was used to study the folding and dynamics of several proteins. We focused most of our effort on DNA- binding proteins that control the transcription of DNA blueprints into the """"""""field copies"""""""" (MRNA) used to build proteins in cells. Fluorescence was used to measure distances between proteins and the sections of DNA they control, to look at the wobbling of proteins in the complex, and to reveal internal changes in the bound protein. We studied """"""""oct-pou"""""""", a bipartite factor able to bind two different classes of DNA control sites and accelerate transcription 100-fold. It was seen to """"""""read"""""""" DNA by changing shape. We also began studies on HIV integrase and Heat Shock Factor. The former incorporates HIV DNA into human DNA, and the latter """"""""turns on"""""""" a stress response by self-association. This year we also continued efforts to adapt our laser instruments to the imaging of tissues. In particular, we demonstrated an electronic laser scanning device that uses discoloration to find BB-sized objects almost an inch inside tissue.
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