Valine, infrared spectrum

Fig. 3.36 Infrared spectrum of ( )-valine recorded as a Nujol mull.

Soon after, Brockmann and Grubhofer (1949) isolated from a culture of 5. chrysomallus another actinomycin which they designated as C. It appeared to be different from actinomycin A or B on the basis of crystal form, melting point, solubihty, infrared spectrum, analytical composition and the nature of the amino acids present (Brockmann and Grubhofer, 1950,1951). Hydrolysates of actinomycin C contained the six amino acids D-valine, sarcosine, L-threonine, L-proline, N-methyl-L-valine and D-alloisoleucine. 

Wright (1937, 1939) had studied infrared spectra of l- and D-amino acids and found them to be identical, but also found that the spectra of l and of D differed from that of the DL-racemate, for example, in the case of cystine, alanine, leucine, valine, and phenylalanine. Glutamic acid, on the other hand, had the same spectrum for the L or dl forms. Acetylleucine exhibits different spectra for the L- and dl-isomers, as is true of acetylisoleucine also (Darmon et al, 1948). Brockmann and Musso (1956) examined L- and DL-alanine and found little difference between their spectra. However, the spectra of l- and OL-serine were quite different. 

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