Satoru Tuzi

The structure and mobility of L-alanine residues of tropomyosin in the solid state as studied by high resolution solid state 13C NMR spectroscopy

Abstract High resolution 13C NMR spectra of tropomyosin,one of the muscle proteins, in the solid state were recorded by the cross polarization—magic angle spinning method and the inversion—recovery method, in order to investigate the higher order structure of the protein through the observation of the 13C chemical shifts of the amino acid residues and their mobility. From these results, the two peaks at 15.8 and 16.7 ppm were assigned to the l -Ala Cβ carbons in the external and internal sites of the coiled-coil structure, respectively, and the molecular motion of the latter carbons is found to be more restricted than that of the former carbons.

The 13C-NMR chemical shift and the higher order structure of l-alanine residues in tropomyosin in the solid state and in solution

Abstract High resolution 13 C-NMR spectra of tropomyosin, one of the muscle proteins, in the solid state were recorded by the cross-polarization/magic-angle spinning method, in order to eludicate the influence of the higher order structure of the protein on the 13 C chemical shifts of the amino acid residues. Furthermore, the conventional high-resolution 13 C-NMR spectra were recorded in solution. We found that the l -alanine C β carbons in the hydrophobic site, which is located between the two α helices of the coiled-coil structure of the protein, show a significant 13 C chemical-shift displacement corresponding to the positions of the residues in the higher order structure.

13C NMR chemical shift and conformation of β-benzyl l-aspartate residues in copolymers of β-benzyl l-aspartate and l-alanine in solution

Abstract High resolution 13 C NMR spectra of copolymers of β-benzyl l -aspartate and l -alanine residues have been recorded, in order to obtain detailed information about the conformational behaviour of the main-chain and side-chains of the β-benzyl l -aspartate residues in solution. The observed results in solution show that the main-chain takes both the right- and left-handed α-helical forms, which is identical with the α-helix conformation in the solid state. The inner side-chains in the right-handed α-helical form have different characteristic conformations in solution and in the solid state. Such chemical shift behaviour of the side-chains suggests that inter-side-chain interactions make the inner side-chains take a conformation with higher energy than the isolated side-chain. Such interactions may account for the fact that in solution the main-chain takes the left-handed α-helix rather than the right-handed one.