PICOSECOND FLUORESCENCE FROM PHYCOCYANIN 612 |
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| Authors: | HENRYK MALAK ROBERT MACCOLL |
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| Institution: | Center for Fluorescence Spectroscopy, Department of Biological Chemistry, University of Maryland at Baltimore, School of Medicine, 660 West Redwood St., Baltimore, MD 21201, USA;Wadsworth Center for Laboratories and Research, New York State Department of Health, Empire State Plaza, P. O. Box 509, Albany, NY 12201-0509 and Department of Biomedical Sciences, State University of New York, Albany, NY 12201, USA |
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| Abstract: | The biliprotein, phycocyanin 612, was purified from a cryptomonad, Hemiselmis virescens. The protein, which is an α2β2 dimer having four spectrally different tetrapyrrole chromophores, was studied using picosecond fluorescence by exciting the various chromophores at three wavelengths, 565, 585 and 615 nm. These wavelengths were chosen to excite selectively the three highest energy chromophores. Decay times were measured as the excitation energy migrated from each of the three excited chromophores to the lowest-energy chromophore. The ps decay times were found to be 9, 13, and 12 ps for excitations at 565, 585, and 615 nm, respectively. A comparison is made between phycocyanin 612 and phycocyanin 645 with regard to the causes of their differing absorption maxima. |
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