以核磁共振光譜技術探討Lanreotide與SDS微胞作用之性質

Lanreotide-SDS micelle interactions via NMR spectroscopy

賴其良(Chi-liang Lai)

指導教授 ： 錢偉鈞

朝陽科技大學/理工學院/應用化學系/碩士(2008年)

摘要

本文以核磁共振光譜技術為主，輔以相關光譜結果探討Lanreotide與SDS(Sodium Dodecyl Sulfate)微胞作用之特徵與性質。Lanreotide(BIM23014)為體制素之八肽類似物，具有比原生體制素還要強的抑制生長激素功能。Lanreotide與體制素受體子型的SSTR2和SSTR5有較明顯的鍵結親和力性。螢光光譜結果顯示Lanreotide進入SDS微胞環境時最高吸收波長產生藍位移及螢光消光現象。螢光實驗證實在SDS微胞環境中Lanreotide之色胺酸殘基位於微胞疏水性的環境中，而螢光強度減弱則源自色胺酸芳香支鏈與賴胺酸支鏈靠近所導致之靜態消光。藉由脈衝磁場梯度實驗可分別測量Lanreotide於水溶液及微胞環境中之擴散係數，並進而估計Lanreotide與SDS微胞之結合常數為6.15×102 M-1(自由能為-15.9 KJ/mol)，顯示此一結合反應為一自發反應。化學位移特性、NOE及耦合常數之分析顯示，Lanreotide在微胞環境下之背骨結構，在D-Trp4-Lys5呈現為β型迴路構型。Lanreotide之構型與芳香環側鏈的空間關係以及其對體制素受體之選擇性之影響在文中進一步的討論。

關鍵字

分子模擬 ； 核磁共振光譜 ； 體制素 ； Lanreotide

並列摘要

The octapeptide Lanreotide (BIM23014) [D-Nal1-cyclo[Cys2-Tyr3-D-Trp4-Lys5-Val6-Cys7]-Thr8-NH2] is an analogous of somatostatin. It has stronger inhibition effect on growth hormone than native somatostatin. Upon binding to its trans-membrane receptors SSTRs, it shows specific affinity to SSTR2 and SSTR5. Nuclear magnetic resonance spectroscopy has been applied to investigate the interaction properties of Lanreotide with SDS micelle. The association constant of Lanreotide-SDS micelle complex is estimated by a two-state approximation based on the diffusion coefficients for Lanreotide in aqueous and micellar solutions, respectively, which is measured by PFG-NMR spectroscopy. The binding constant is estimated to have a value of 6.12×102 M-1, which implied that the interaction between Lanreotide and SDS micelle was spontaneous under current condition. When association with SDS micelle, Lanreotide adopts a β-turn centered at D-Trp4-Lys5. The correlation between the relative positions of the aromatic side-chain of the peptide and its receptor affinity is further discussed.

並列關鍵字

Lanreotide ； somatostatin ； molecular simulation ； nuclear magnetic resonance

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