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1、聚合物在蛋白质分离中的应用蛋白质是由氨基酸通过酰胺键连接而成的高分子，两性，存在等电点，因其空间结构的复杂性，有亲水或疏水之分。蛋白质在低于等电点时会带上正电荷，在高于等电点时带负电荷若缓冲溶液的pH值低于蛋白质等电点，蛋白质则吸附H 而带正电荷，由于静电相互作用，蛋白质与管壁发生吸附。（a）碱性蛋白质（pI8）所带电荷量随pH的变化曲线； （b）在pH4时，碱性蛋白质（pI8）与毛细管壁发生吸附. 极端极端pH值法值法vpH高于蛋白质的pI时，毛细管内壁对蛋白质产生静电排斥抑制吸附，但是，蛋白质存在的自然状态为pH410，高pH如11.0时，容易使蛋白质变性或者水解。v pH小于1.5（熔融
2、硅或石英的等电点）时，蛋白质的质子化导致其质荷比差别较小，分辨率难以提高。v 对等电点相近的蛋白质不易实现分离。v一般认为，使蛋白质混合物分离的首选pH值应和蛋白质混合物的pKa值基本一致。McManigill D. Anal Chem,1986，58：166170.2. 添加小分子添加剂添加小分子添加剂v表面活性剂：季铵盐和氟化的阳离子表面活性剂。v中性盐：如磷酸盐，硫酸钾等。v胺类：三乙醇胺、三乙胺、N-乙基二乙醇胺，N,N, N,N-四甲基-1,3 -丁二胺（TMBD）等。v有机溶剂：醇类、乙腈、丙酮、四氢呋喃、二甲亚砜等，其中最常用的是甲醇和乙腈。v 选用极端pH值或添加小分子添加剂的
3、方法虽然能从一定程度上降低蛋白质吸附，但是容易导致蛋白质聚集和变性。目前最常用的方法是用聚合物对毛细管内壁进行改性处理。何金兰等何金兰等.高效毛细管电泳高效毛细管电泳. 北京：科学出版社，北京：科学出版社，1996, 7275.Verzola B, Gelfi C, Righetti P G. J Chromatogr A，2000，868：8599.Corradini D, Cannarsa G, Fabbri E, et al. J Chromatogr A，1995，709：127134.Corradini D, Cannarsa G. Electrophoresis，1995，16：6
4、30635.聚合物涂覆毛细管内壁抑制蛋白质吸附(1) 化学键合的毛细管涂层化学键合的毛细管涂层化学键合的交联的PVA涂层对4种碱性蛋白质实现第2次和第902次分离的电泳图谱 样品浓度：50ug/mL的（1）细胞色素C，（2）溶解酵素，（3）胰蛋白酶原，（4）胰凝乳蛋白酶原。分离条件：毛细管，内径50m，总长48.5cm（有效长度40cm）；注入，3 kV, 5 s；缓冲液，40mM磷酸钠；分离，309 V/cm(2)物理吸附的毛细管涂层物理吸附的毛细管涂层目前使用的聚合物：中性的聚合物已经广泛用于DNA和其它一些生物大分子的分析，但是由于蛋白质的吸附作用，使得对蛋白质的分析仍有一定难度。亲水性
5、的聚合物如甲基纤维素，聚糖等不能很好的吸附在管壁上，稳定性差。带疏水基团的聚合物聚乙烯基吡咯烷酮，聚N,N-二甲基丙烯酰胺可以形成稳定的涂层，但是由于疏水基团与蛋白质之间的相互作用使得分离效率下降。Madabhushi R S. Electrophoresis，1998，19：224230. Verzola B, Gelfi C, Righetti P G. J Chromatogr A，2000，874：293303.羟乙基纤维素的改性Formation of the cat-HEC Schematic diagram of adsorption of cat-HEC onto silica
6、 surface.(1) Cat-HECNo.HEC(g) Glycidyltrimethylamminium chloride (g)Viscosity (mp.s) Nitrogen content (%) Cat-HEC-110.02.53800.8Cat-HEC-210.05.03751.3Cat-HEC-310.07.53701.7 Preparation and properties of Cat-HECElectroosmotic flow as a function of pH. Comparison between a bare fused-silica capillary,
7、 HEC and cat-HEC coated capillary Electropherograms of a mixture of standard proteins. Separations were carried out using cat-HEC-2 coated capillary 1 = Lysozyme; 2 = Cytochrome C; 3 = Ribonuclease A.Electropherograms of a mixture of standard proteins at pH 4.6. ProteinBare capillaryN (plate/m) bHEC
8、N (plate/m) RSD (%)Cat-HEC-2N(plate/m) RSD (%)Cytochrome C93001040003.521860000.86Lysozyme-1620002.452650000.85Ribonuclease A173001800003.562820000.96Electrophoresis, 2008, 29, 1460-1466.Electropherograms of a mixture of standard proteins in different pH. Separations were carried out using cat-HEC-2
9、 coated capillary 1 = Lysozyme; 2 = Cytochrome C; 3 = Ribonuclease A.Migration time reproducibility (n = 3) and peak efficiency of proteins separated in polymer-coated capillaries at pH 4.6 () HEC-g-P4VPFormation of the HEC-g-P4VP Electroosmotic flow as a function of pH. Comparison between a bare fu
10、sed-silica capillary, HEC and HEC-g-P4VP coated capillaryElectropherograms of a mixture of standard proteins. Separations were carried out using cat-HEC-g-P4VP coated capillary. 1 = Lysozyme; 2 = Cytochrome C; 3 = Ribonuclease A.结构规整的聚合物PEO-b-P4VPNOOBrOOOONN+BrsamplessamplesMn 1H NMRa) (10-4)Mn， GPC
11、b) (10-4)Mw/Mn (GPC)PEOPEO113113- -b b-P4VP-P4VP45450.971.41.21PEOPEO113113- -b b-P4VP-P4VP90901.442.01.29PEOPEO113113- -b b-P4VP-P4VP1131131.692.41.26PEOPEO113113- -b b-P4VP-P4VP2942943.595.21.35a. Mn of PEO-b-P4VP estimated by 1H NMR； b. Mn of PEO-b-P4VP determined by GPC.Formation of the PEO-b-P4
12、VP 1H NMR and GPC data of PEO-b-P4VP copolymers Effect of molecular weight of P4VP block on the separation of basic proteins at pH 4.6. 1, lysozyme; 2, cytochrome c; 3, ribonuclease. (A) Typical TEM images of (a) PEO113-b-P4VP45, (b) PEO113-b-P4VP90, (c) PEO113-b-P4VP113, and (d) PEO113-b-P4VP294; (
13、B) Schematic illustration of copolymers of different morphologies capillary coating procedure (a) PEO113-b-P4VP45, (b) PEO113-b-P4VP90, (c) PEO113-b-P4VP113, and (d) PEO113-b-P4VP294Analysis of saliva samples by PEO113-b-P4VP294 coated capillary. Saliva samples were diluted to 2-fold using deionized
14、 water. Samples (A) without and (B) with spiking of 0.2mg / mL lysozyme were injected. Separation conditions: 40mM phosphate-citrate buffer, pH 5.1; 500V/cm; 40cm capillary (30 cm to the detector); temperature 25. Effect of buffer pH on the separation of basic proteins. separations were taken in PEO
15、113-b-P4VP294 coated capillary Electropherograms of plasma sample in bare capillary (A) and a PEO113-b-P4VP294 coated capillary (B). Separation buffer: 19mM NaOH-Na2B4O7 at pH 9.7. HSA, human serum albumin; 1-AT, 1-antitrypsin; 2-M, 2-macroglobulin; -lp, -lipoprotein; Tf, transferrin; IgA, immunoglo
16、bulin A; IgG, immunoglobulin G.Electrophoresis 2008,29, 2812-28193. 多功能分离介质的合成及应用研究多功能分离介质的合成及应用研究(1) HEC-g-PDMA研究背景能进行DNA、蛋白质、氨基酸、同分异构体等的分离Separation of 174/HaeIII digest by CE withHEC-g-PDMA at (a) 1.0% w/v; (b) 1.5% w/v; (c) 2.0% w/v Effect of pH values on separations of basic proteins using HEC-
17、g-PDMA coated capillary.1, lysozyme; 2, cytochrome c; 3, ribonuclease A.Electrophoresis,2008, 29, 43514354. (2) quasi-interpenetrating network of LPA andPDMA Properties of quasi-IPN containing LPA with different molecular massesPolymerMv of LPA (MDa)Intrinsic viscosity of LPA(mL/g) Molar ratio of AM
18、/DMAIntrinsic viscosity of IPN (mL/g)quasi-IPN -10.2510618.6:188quasi-IPN -20.251065.1:1145quasi-IPN -30.471686.8:1167quasi-IPN -40.471682.6:1266quasi-IPN -50.922786.5:1260quasi-IPN -64.609288.4:1840 EOF as a function of pH. Electropherograms of a mixture of standard proteins. Separation of 174/HaeI
19、II digest by CE with quasi-IPN-3 at (a) 2% w/v; (b) 3% w/v; (c) 4% w/v; (d) 4% w/v. Conditions: Separation electric field strength of (a), (b), and (c) is 6 kV, separation electric field strength of (d) is 8 kV. Separation of basic proteins using quasi-IPN-3 coated capillary at different pH values. 1=cytochrome c; 2=Lysozyme; 3= Ribonuclease A.J. Sep. Sci., 2009, 32, 671-680. v目前仍未找到一种普适性的涂层对所有种类的蛋白质分离都是有效的，因为不同种类的蛋白质等电点不同，这就需要用于管壁涂覆的聚合物涂层有较宽的pH适用范围，并且期望可以通过改变缓冲溶液的pH值实现对电渗流大小的控制，这应该是未来用于分离蛋白质的聚合物涂层的一个发展方向。
