Nitro-phenylalanine: a novel sensor for heat transfer in peptides.

Karin Haiser, Florian O Koller, Markus Huber, Nadja Regner, Tobias E Schrader, Wolfgang J Schreier, Wolfgang Zinth

Index: J. Phys. Chem. A 115(11) , 2169-75, (2011)

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Abstract

Femtosecond IR-pump-IR-probe experiments with independently tunable pulses are used to monitor the ultrafast response of selected IR absorption bands to vibrational excitation of other modes of Fmoc-nitrophenylalanine. The absorptions of both NO(2)-bands change rapidly within <2 ps upon excitation of other vibrational modes. The results point to considerable coupling between the monitored NO(2) modes and the initially excited modes or low-frequency modes. The latter are populated by a rapid energy redistribution process. The strong IR absorption of the NO(2) stretching bands and the intense coupling to other modes makes the nitro group of nitrophenylalanine a sensitive monitor for vibrational energy arriving at this amino acid.