Optical rotatory dispersion of polypeptides and proteins

Abstract

“THE invention in 1866 of the Bunsen burner inhibited the more laborious study of rotatory dispersion by making it almost too easy to work with the nearly monochromatic light of the sodium flame, and in this way brought to an end the fertile era which Biot had inaugurated half a century before.” Thus wrote Lowry in his classical study of optical rotatory power. l As a matter of fact, during the time of Biot and his famous pupil, Pasteur, nearly all studies of optical activity were associated with measurements of optical rotatory dispersion. It was indeed most unfortunate that much valuable information was lost in later years through the extensive use of the sodium lamp by almost all the workers in this field. Within the last five years, however, we have witnessed an increasing interest in the optical rotatory power, both theoretically and experimentally. With the availability of commercial spectropolarimeters, the optical rotatory dispersion studies have experienced a rebirth, and have already yielded many fruitful findings as a result of new developments. On the one hand, this technique has been extensively applied to the structural studies of organic compounds, as evidenced by the beautiful work of Djerassi et al. * Of equal importance are the applications of optical rotatory dispersion to the study of polypeptide and protein conformations. It is at the latter aspect that the present paper will be aimed. Already the vast interest in this field has resulted in the appearance of several excellent reviews.3-6 A monograph on synthetic polypeptides has also been published which describes in detail the work of the English school. 7 Therefore (and taking into consideration the limits of time and space imposed upon me) it seems superfluous to discuss recently publishd work; nor is it necessary to describe the work of some of the distinguished participants present at this symposium. Rather, we will limit our brief review to some of our early work, which I, myself, had the good fortune to observe closely. Some of the older proposals and interpretations will also be re-examined in view of later developments.