Electronic spectroscopy of cold, protonated tryptophan and tyrosine

We report here a new method to obtain electronic spectra of biomolecular ions that are produced in the gas phase by electrospray and cooled to ~10K in a 22-pole ion trap, and we demonstrate this technique by applying it to protonated tryptophan and tyrosine. Cooling in the trap greatly simplifies the spectrum of protonated tyrosine, which exhibits a well-defined band origin and clearly resolved low frequency vibrational bands. In contrast, the spectrum of protonated tryptophan exhibits only broad features, even at low temperatures, suggesting that a fast non-radiative process broadens the individual vibronic features, even upon excitation at the electronic band origin. The method demonstrated here should be applicable to a wide variety of biological molecules.

Published in:
Journal of the American Chemical Society, 128, 2816

 Record created 2006-01-03, last modified 2018-01-27

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