title: Electronic spectroscopy of cold, protonated tryptophan and tyrosine.
abstract: 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 approximately 10 K 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 nonradiative 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.
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Boyarkin
authors.forename: Sébastien R
authors.initials: SR
authors.lastname: Mercier
authors.forename: Anthi
authors.initials: A
authors.lastname: Kamariotis
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Rizzo
mesh_terms: D003080:Cold Temperature; D005740:Gases; D013058:Mass Spectrometry / Q000379:methods; D010777:Photochemistry; D011522:Protons; D013057:Spectrum Analysis; D014364:Tryptophan / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D005740:Gases; D011522:Protons; D014443:Tyrosine; D014364:Tryptophan