Chapter 4 Absorption, circular dichroism and optical rotatory dispersion of polypeptides, proteins, prosthetic groups and biomembranes

Abstract

Publisher Summary The physical methods of absorption, circular dichroism (CD), and optical rotatory dispersion (ORD) are invaluable laboratory tools that are useful at every degree of familiarity with the method. The physical processes of absorption, refraction, circular dichroism, and optical rotatory dispersion are closely inter-related, such that mechanistic discussions of the latter two require adequate consideration of the former two. The chapter begins with consideration of basic elements and terminologies of absorption and refraction, and then treats circular dichroism and optical rotatory dispersion, and in doing so, provides prosthetic group examples of excitation resonance interaction and of the dispersion force interactions giving rise to hyper- and hypochromism in absorption and to reciprocal relations in optical rotation. In addition, the chapter also presents characteristic absorption and circular dichroism spectra of some five or more regular protein and polypeptide conformations. Finally, the chapter reviews the particular problem of applying these methods to the timely study of biomembrane is presented by considering the model poly-L-glutamic acid particulate system and by applying the analysis to the purple membrane of Halobacterium halobium .