【作者】 武红丽；

【导师】 欧阳平凯； 屠春燕；

【作者基本信息】 南京工业大学 ， 生物化工， 2004， 硕士

【摘要】 对于固相多肽合成来说,防止消旋化是一个十分重要的问题。为了保证多肽产物的光学纯度,除了在合成过程中严格控制消旋化的发生以外,还必须严格采用光学纯的原料-N-Fmoc 保护氨基酸。因此, N-Fmoc 保护氨基酸对映体的检测对于光学活性多肽的合成至关重要。本文选取具有代表性的五种保护氨基酸,根据保护氨基酸的结构与性质的差异,分别采用毛细管区带电泳、毛细管胶束电动色谱以及非水毛细管电泳进行了手性拆分。不同毛细管电泳拆分体系的选择与运用,为建立拆分 N-Fmoc 保护氨基酸方法提供了可能。具体内容如下:1、毛细管区带电泳拆分选择 DM-β-CD 为手性选择剂实现对 Fmoc-Asp(otBu)-OH、Fmoc-Val-OH 的毛细管区带电泳分离。对毛细管电泳的分离条件进行了优化,最终获得分离色谱条件为:毛细管 50μm×40 ㎝(有效长度为 30 ㎝);电解液:40mmol·L-1磷酸二氢钠溶液,内含商品化 20mmol·L-1 2,6-二甲基-β-环糊精,用 Tris 调 pH 为 5.0;电压:20kv;温度:毛细管柱温 25℃,样品恒温 25℃;电极:正向;检测波长:λ=214nm。在此色谱条件下,Fmoc-Asp(otBu)-OH、Fmoc-Val-OH 对映体的分离度分别为 2.54 和 1.62。并对 Fmoc-Asp(otBu)-OH、Fmoc-Val-OH 的实验方法进行了验证,结果显示该方法准确,可行。同时对环糊精拆分原理进行了初步的推测:对于两种 N-Fmoc 保护氨基酸对映体来说,有可能是保护氨基的疏水骨架-芴甲氧羰酰基从粗端口进入环糊精内部疏水空腔中,形成主-客体复合物。在环糊精的空腔外的氨基酸的羧基和侧链,与环糊精的空腔外缘仲羟基之间形成氢键而达到手性识别。2、毛细管胶束电动色谱拆分选择γ-CD 为手性选择剂实现对 N-Fmoc-Lys(Boc)-OH 的毛细管胶束电动色谱分离。对毛细管电动色谱的分离条件进行了优化,最终获得分离色谱条件为:毛细管 50μm×40 ㎝(有效长度为 30 ㎝);电解液:40mmol·L-1磷酸二氢钠溶液,内含商品化 60mmol·L-1γ-环糊精,100 mmol·L-1十二烷基磺酸钠(SDS),用氢 I<WP=5>摘 要氧化钠调 pH 为 8.3;电压:18kv;温度:毛细管柱温 35℃,样品恒温 25℃;电极:正向;检测波长:λ=214nm;在此色谱条件下,N-Fmoc-Lys(Boc)-OH 的分离度为 1.2;对 N-Fmoc-Lys(Boc)-OH 的实验方法进行了验证,结果显示该方法准确,可行。3、非水离子对毛细管电泳拆分选择奎宁为手性选择剂,实现对 Fmoc-Tyr-(tBu)-OH 和 Fmoc-Trp-(Boc)-OH对映体的非水体系逆流离子对毛细管电色谱分离。其分离原理为:在测定的 pH范围内分离时,保护氨基酸带负电,朝检测窗口方向运动;奎宁带正电,与电渗流相同背向检测窗口运动。游离的手性选择剂奎宁和待分析物则分别向阴极或阳极迁移,形成逆流分离过程,从而形成逆流离子对手性电色谱。在二者相互运动过程中,保护氨基酸与奎宁形成离子对,并通过其它氢键、疏水作用等因素实现对映体的手性识别。分离是建立在不同的离子对平衡常数的基础之上。通过对非水体系逆流离子对毛细管电色谱的原理分析,对色谱的分离条件进行了优化,最终获得分离色谱条件为:石英未涂层毛细管 50μm×40 ㎝(有效长度为 30 ㎝);电解液:乙醇:甲醇(60:40),四丁基氢氧化铵 12.5 mmoL/L;用乙酸调节 pH 约为 6.5 ;手性选择剂:奎宁 10 mmoL/L;电压:25kv;温度:毛细管柱温 20℃,样品恒温 25℃;电极:反向;检测波长:λ=254nm。在此色谱条件下,Fmoc-Tyr-(tBu)-OH 和 Fmoc-Trp-(Boc)-OH 的分离度分别为 1.64 和 1.23;对 Fmoc-Tyr-(tBu)-OH 和 Fmoc-Trp-(Boc)-OH 的实验方法进行了验证,结果显示该方法准确,可行。更多还原

【Abstract】 For solid-phase synthetic peptide, the racemic phenomenon must to be controlled.Beside keeping react process, we also selected the enough optically pure rawmaterial—N-Fmoc group protected amino acids. So the optical detection of thesematerials was very important. In this paper, we chirally separated five typical N-Fmoc amino acids:Fmoc-Asp(otBu)-OH, Fmoc-Val-OH, Fmoc-Lys-(Boc)-OH, Fmoc-Tyr-(tBu)-OHand Fmoc-Trp-(Boc)-OH by three separation model, because of the solibility of theN-Fmoc amino acids in water. Through the research, we get the following conclusion:1 The enantioseparation of N-Fmoc amino acids by CZE The Fmoc-Asp(otBu)-OH and Fmoc-Val-OH was resoluted with DM-β-CD aschiral selector by capillary zone electrophoresis (CZE). The Rs of the two N-Fmocamino acids were 2.54 and 1.62, respectively. The composition of the backgroundelectrolyte was 20 mM chiral selector-- DM-β-CD in a 40 mM phosphate-Tris buffer(pH5.0) and the enantioseparations were performed at 25oC, at 20 kV and UVdetection wavelength at 214 nm.This method was sample, quick and selective. For two enantiomer, the hydrophobic group – N-Fmoc come into the CD’scavum, then formed the host-guest complex. The enantiomeric selectivity of thecomplex is based on the hydrogen bond of amino acid’s carboxyl group or side groupand the CD’s second hydroxyl group.2 The enantioseparation of N-Fmoc amino acids by MEKC The Fmoc-Lys-(Boc)-OH was enantioseparated with γ-CD as chiral selector andsodium dodecyl sufate (SDS) as micellar phase by micellar electrokineticchromatography(MEKC). The Rs of the N-Fmoc amino acid was1.2. Electrophoreticconditions employed was: 60 mM chiral selector--γ-CD and 100 mM SDS in a40 mM phosphate buffer (pH8.3), the enantioseparations temperature at 35oC,detection voltage at 18 kV and UV detection wavelength at 214 nm.This method wassample, quick and selective. i<WP=7>ABSTRACT3 the enantioseparation of N-Fmoc amino acids by NACE The Fmoc-Tyr-(tBu)-OH and Fmoc-Trp-(Boc)-OH was chirally separated withquinine as chiral selector by non-aqueous capillary electrophoresis (NACE). The Rsof the two N-Fmoc amino acids were 1.64 and 1.23 respectively. The composition ofthe background electrolyte was 12.5 mM tetrabutyl amino hydroxyl-acetyl acidbuffer(pH6.5), and 10 mM chiral selector in an ethanol–methanol (60:40, v/v) mixtureand the enantioseparations were performed at 20oC, in the reversed polarity mode at-25 kV and UV detection wavelength at 254 nm.This method was sample, quick andselective. The quinine was cation and move to cathode, but the N-Fmoc amino acids wereanion and move to anode at pH6.5. Because the movement was reverse, thecounter-current ion-pair chromatrography was formed. In this enantioseparation, theion-pair of the quinine and the N-Fmoc amino acids was not important. Based on theH-bond and hydrophobic interaction, the enantiomers were resoluted.更多还原