Reaction-induced infrared difference spectroscopy for the study of proteinreaction mechanisms

This paper reviews state-of-the-art reaction-induced infrared difference sp ectroscopy of proteins. This technique enables detailed characterization of enzyme function on the level of single bonds of proteins, cofactors, or su bstrates. The following methods to initiate a reaction in the infrared samp le are discussed: (i) light-induced difference spectroscopy, (ii) attenuate d total reflection with buffer exchange, (iii) the infrared variant of stop ped and continuous flow, (iv) temperature and pressure jump, (v) photolytic al release of effector substances from caged compounds, (vi) equilibrium el ectrochemistry, and (vii) photoreduction. Illustrating applications are giv en including hot topics from the fields of bioenergetics, protein folding, and molecule-protein interaction.