Solid-state 17 O NMR of amino acids
Solid-state 17 O NMR of amino acids
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氨基酸的固态 17 O NMR
DOI：
10.1021/jp049958x
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发表时间：
2004
影响因子：
3.3
通讯作者：
R. Dupree
中科院分区：
文献类型：
--
作者：
K. J. Pike;V. Lemaitre;A. Kukol;T. Anupõld;A. Samoson;A. Howes;A. Watts;Mark E. Smith;R. Dupree
本文报道了14种氨基酸的~（17）O固体核磁共振谱，大大增加了研究的数量。在大多数情况下，良好分离的共振，从羰基和羟基氧与不同的二阶四极线形状观察到使用600 MHz的光谱仪与快速魔角旋转（MAS）。这与通常从溶液中的氨基酸中看到的运动平均共振形成对比。对于氨基酸，双角旋转（DOR）使谱线宽度减少40倍以上，从而提供非常高的分辨率（100 ppm）光谱。用~ 1H-去偶DOR法对丙氨酸中的氧线和L-谷氨酸盐酸盐中的羰基氧进行了归属。氨基酸的NMR相互作用参数显示XQ的变化很大，从6.4到8.6 MHz，η从0.0到0.9，δiso从83到353 ppm。在14.1 T下获得的MAS NMR线形的高质量意味着即使是参数的微小变化也可以非常准确地推断出来，从而提供了17 O NMR作为这些化合物和相关化合物结构变化的灵敏探针的可能性。谷氨酸盐酸盐的D-和L-形式显示具有相同的NMR参数，误差范围内，这与文献中报道的D，L-形式的NMR参数非常不同。δiso与羰基氧的C-O键长有很强的相关性（~ 1200 ppm/A）。在这些数据的基础上，在更复杂的多肽和蛋白质中富集特定的氨基酸可以提供关于生物分子中不同位点的键合和功能的位点选择性信息。对这些物质的可能检测限进行了估计。
17 O solid-state NMR from 14 amino acids is reported here, greatly increasing the number investigated. In most cases well-separated resonances from carbonyl and hydroxyl oxygens with distinct second-order quadrupolar line shapes are observed using a 600 MHz spectrometer with fast magic angle spinning (MAS). This is in contrast to the motionally averaged resonances usually seen from amino acids in solution. For amino acids double-angle rotation (DOR) produces a decrease in the line width by more than a factor of 40, providing very high resolution, ∼ 1 ppm, spectra. The oxygen lines in alanine and the carbonyl oxygens in L-glutamic acid hydrochloride are assigned using 1H-decoupled DOR. The NMR interaction parameters for amino acids show a wide variation of XQ, from 6.4 to 8.6 MHz, η from 0.0 to 0.9, and δiso from 83 to 353 ppm. The high quality of the MAS NMR line shapes obtained at 14.1 T means that even small changes in parameters can be very accurately deduced, offering the possibility of 17O NMR as a sensitive probe of structural changes in these and related compounds. The D- and L-forms of glutamic acid hydrochloride are shown to have the same NMR parameters to within error, which are very different from those reported in the literature for the D,L-form. A strong correlation (∼-1200 ppm/A) is found between δiso and the C-O bond length of the carbonyl oxygens. On the basis of these data, enriching specific amino acids in more complex polypeptides and proteins could provide site-selective information about the bonding and functionality of different sites in biomolecules. An estimate is made of the possible detection limit for such species.