Low-Temperature Spectroscopy

This chapter provides some practical advice on the way to do low-temperature spectroscopy. The chapter discusses the internal structure of visible absorption spectra and their temperature dependence. It also discusses the utilization of low-temperature spectroscopy to probe protein dynamics. The chapter goes beyond the traditional use of low temperatures to trap intermediate chemical states and to speculate the insight that low-temperature spectroscopy provides the role of protein dynamics in controlling chemical reactions. Probably the main reason for the neglect of low-temperature spectroscopy in biophysics is the unstated opinion of many biophysicists that these kinds of studies are irrelevant to the biological aspects of the reaction. Another reason, connected to the first claim of irrelevance, is the fact that any such study of low-temperature dynamics necessarily involves construction of theoretical models, and in complex molecules this is a notoriously difficult and speculative thing to do. Thus, the chapter provides a comprehensive review of all low-temperature studies on biological systems.