Observation of low frequency vibrational modes in a mutant of the green fluorescent protein

Abstract

Coherent vibrational dynamics in a mutant of the green fluorescent protein are studied by diffractive optic ultrafast transient grating spectroscopy. Two low frequency (<100 cm⁻¹) modes are observed. We propose that one at 95 cm⁻¹ may be associated with intramolecular torsional motion in the excited state. The possible importance of such modes in understanding the very high quantum yield of the intact GFP is discussed.