導(dǎo)讀：近日,，中國科學(xué)院青島生物能源與過程研究所仿真模擬團(tuán)隊(duì)負(fù)責(zé)人姚禮山研究員與美國國立健康中心Ad Bax研究小組合作,，在《美國化學(xué)會(huì)志》（JACS）上發(fā)表了一篇關(guān)于蛋白質(zhì)主鏈酰胺基上質(zhì)子的化學(xué)位移各項(xiàng)異性張量的研究文章。
生物谷提供文章索引<<<
J.AM.CHEM.SOC. doi：10.1021/ja103629e.
The Impact of Hydrogen Bonding on Amide 1H Chemical Shift
Anisotropy Studied by Cross-Correlated Relaxation and Liquid Crystal NMR Spectroscopy
Lishan Yao, Alexander Grishaev, Gabriel Cornilescu, and Ad Bax
近日,，中國科學(xué)院青島生物能源與過程研究所仿真模擬團(tuán)隊(duì)負(fù)責(zé)人姚禮山研究員與美國國立健康中心Ad Bax研究小組合作,，在《美國化學(xué)會(huì)志》（JACS）上發(fā)表了一篇關(guān)于蛋白質(zhì)主鏈酰胺基上質(zhì)子的化學(xué)位移各項(xiàng)異性張量的研究文章。
該研究以蛋白質(zhì)GB3為研究對(duì)象,，測(cè)量了大量的殘余化學(xué)位移和化學(xué)位移各項(xiàng)異性/偶極-偶極交叉弛豫數(shù)據(jù),。通過模型擬合，研究首次確定出了酰胺基質(zhì)子的化學(xué)位移各項(xiàng)異性張量而無需引入人為的假設(shè)——即該張量是相對(duì)于肽平面對(duì)稱,。
實(shí)驗(yàn)結(jié)果表明,，不同酰胺基質(zhì)子的化學(xué)位移各項(xiàng)異性張量有較大差異。進(jìn)一步的密度泛函量子力學(xué)計(jì)算表明,，該差異主要是由酰胺基質(zhì)子和其他基團(tuán)形成氫鍵強(qiáng)弱不同造成的,。文章提出一個(gè)經(jīng)驗(yàn)公式用來描述氫鍵和該張量的關(guān)系，并達(dá)到較好的效果,。該研究還發(fā)現(xiàn),，不同的酰胺基質(zhì)子TROSY效應(yīng)差別很大，平均大約1200兆赫茲的磁場(chǎng)會(huì)產(chǎn)生最窄的線寬,。
該研究為更好地理解酰胺基質(zhì)子的化學(xué)位移各項(xiàng)異性張量奠定了基礎(chǔ),。研究中發(fā)展和使用的一些先進(jìn)技術(shù)方法對(duì)其他相關(guān)研究也有借鑒意義。（生物谷Bioon.com）
生物谷推薦英文摘要>>>
Site-specific 1H chemical shift anisotropy (CSA) tensors have been derived for the well-ordered backbone amide moieties in the B3 domain of protein G (GB3). Experimental input data include residual chemical shift anisotropy (RCSA), measured in six mutants that align differently relative to the static magnetic field when dissolved in a liquid crystalline Pf1 suspension, and cross-correlated relaxation rates between the 1HN CSA tensor and either the 1H-15N, the 1H-13C′, or the 1H-13CR dipolar interactions. Analyses with the assumption that the 1HN CSA tensor is symmetric with respect to the peptide plane (three-parameter fit) or without this premise (five-parameter fit) yield very similar results, confirming the robustness of the experimental input data, and that, to a good approximation, one of the principal components orients orthogonal to the peptide plane. 1HN CSA tensors are found to deviate strongly from axial symmetry, with the most shielded tensor component roughly parallel to the N-H vector, and the least shielded component orthogonal to the peptide plane. DFT calculations on pairs of N-methyl acetamide and acetamide in H-bonded geometries taken from the GB3 X-ray structure correlate with experimental data and indicate that H-bonding effects dominate variations in the 1HN CSA. Using experimentally derived 1HN CSA tensors, the optimal relaxation interference effect needed for narrowest 1HN TROSY line widths is found at ～1200 MHz.
