Steric structure of L-proline oligopeptides. I. Infrared absorption spectra of the oligopeptides and poly-L-proline

✍ Scribed by T. Isemura; H. Okabayashi; S. Sakakibara

• Publisher: Wiley (John Wiley & Sons)
• Year: 1968
• Tongue: English
• Weight: 516 KB
• Volume: 6
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1968.360060306

✦ Synopsis

Poly-cprolines I and I1 were differentiated by the characteristic bands in the far infrared region. Form I showed two broad bands at about 280 and 160 cm.-l and form 11 two bands at 400 and 670 ern.-'. Furthermore, three broad bands at about 250,200, and 100 cm.-l were observed in the spectrum for form 11. Infrared absorption bands of the pentamer, hexamer, and octamer of tert-amyloxycarbonyl-cproline were almost similar to those of poly-L-proline I1 in the 1800-75 cm.-l region. I n the far-infrared region, especially, the absorption bands of these three oligopeptidea were in good agreement with that of ply-L-proline 11. Accordingly we concluded that the molecules of pentamer, hexamer, and oetamer had a helical structure of a left-handed threefold screw axis. The tetrapeptide of tert-amyloxycarbonyl-L-proline might also have a left+ handed helix, probably one turn, since the tetramer clearly showed an absorption band at about 400 cm.-' characteristic of poly-L-proline 11.