Studies of Proteins and Polypeptides

In the late 1940 s Darmon and Sutherland (1947), Astbury et al. (1948), Sutherland (1950), and later the Courtaulds workers obtained data on the spectra of synthetic polypeptides. 

Type of vibration a-Form /5-Form Not hydrogen-bonded 

Ambrose and Elliott (1951) investigated the dichroism of the three bands above and obtained the following information about qualitative dichroic properties (Table 10.2). If we assume that the C=0 and N—H stretching vibrations have transition 

Elliott and Malcolm (1956 ) and Downie et al. (1957) showed that the procedure of identification of a- or )3-structure by correlation with frequency ranges listed in Table 10.1 can lead to erroneous conclusions in special cases. The Miyazawa theory (to be discussed later) has made possible an analysis more sophisticated than the empirical method mentioned here. 

If we consider that the three major absorption bands of the amide group given above actually represent normal modes of motion of the whole amide linkage, along 

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