Packing Arrangements and Inter-Sheet Interaction of Alanine Oligopeptides as Revealed by Relaxation Parameters Obtained From High-Resolution (13)C Solid-State NMR.
Related Articles Packing Arrangements and Inter-Sheet Interaction of Alanine Oligopeptides as Revealed by Relaxation Parameters Obtained From High-Resolution (13)C Solid-State NMR.
J Phys Chem B. 2017 Sep 05;:
Authors: Naito A, Tasei Y, Nishimura A, Asakura T
Abstract
Alanine oligopeptides provide a key structure of the crystalline domains of the silks from spiders and wild silkworm, and also the sequences included in proteins such as antifreeze proteins and amyloids. In this paper, the local dynamics of alanine oligopeptides, (Ala)3, (Ala)4 and (Ala)6 were examined by high-resolution (13)C solid-state NMR. The (13)C spin-lattice relaxation times (T1's) for the C?4 carbons of antiparallel (AP)-?-sheet (Ala)4 significantly prolonged and the correlation time was estimated as 3.6 x 10(-11) sec which was shorter than those of other carbons in the AP-?-sheet (Ala)4 (2.8 x 10(-10) sec). The T1 values for the C? carbons of (Ala)6 showed significantly longer correlation time (8.8 x 10(-9) sec) than those of AP-?-sheet (Ala)4. It is thus revealed that AP-?-sheet (Ala)6 exhibited stronger inter-sheet interaction than those of AP-?-sheet (Ala)4. The (13)C spin-spin relaxation times (T2's) for the C?4 carbons showed longer than those of the other C?1-3 carbons of AP-?-sheet (Ala)4. T2 values of C? carbons reflect the slow time-scale (~70 kHz) backbone motions. The C-terminal forms strong hydrogen bonds with water molecules and thus the backbone motion is slower than ~70 kHz, while the central backbone motions are faster than ~70 kHz in AP-?-sheet (Ala)4.
PMID: 28872862 [PubMed - as supplied by publisher]
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