13C CHEMICAL SHIFTS OF SOLID POLYPEPTIDES BY CROSS POLARIZATION/MAGIC ANGLE SPINNING (CP/MAS) NMR SPECTROSCOPY: CONFORMATION-DEPENDENT 13C SHIFTS CHARACTERISTIC OF α-HELIX AND β-SHEET FORMS

Conformation-dependent 13C chemical shifts of poly(l-valine), poly(l-isoleucine), and poly(lleucine) of α-helix and β-sheet forms in solid state were measured by cross polarization/magic angle spinning (CP/MAS) NMR spectroscopy. It is found that 13C shifts of Cα, Cβ and carbonyl carbons of the first two polypeptides exhibit significant conformation-dependent change, while those of poly(l-leucine) show little change.