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1、蛋白质的吸附、变性及污染防治蛋白质的吸附、变性及污染防治蛋白质的吸附、变性及污染防治蛋白质的吸附、变性及污染防治l引起通量下降的主要原因l蛋白质的吸附过程l膜过程的污染防治与清洗引起通量下降的原因引起通量下降的原因通量时间蛋白质的一般性质蛋白质的一般性质蛋白质是由许多氨基酸通过肽键相连而成的高分子物 质，各种蛋白质中氨基酸的组成排列顺序和肽链的立体 结构都各不相同。蛋白质分子中氨基酸残基的连接方式 和排列顺序就是蛋白质的化学结构（也叫一级结构）。其中R1,R2,R3,R4代表各种氨基酸含有不同基团的侧 链，它对保持蛋白质看见结构和行使蛋白质的功能起着重 要作用，每个NHCH(R)CO- 称为氨
2、基酸残基。蛋白质除了上述的一级结构外，还有二级结构（螺旋结构、折叠结 构、转角结构、自由回转等）、三级结构（在二级结构基础上形成的很不 规则的构象）和四级结构（由两条或两条以上的具有三级结构的多肽链聚 合而成特定的构象），因此蛋白质分子除通常主要的化学键外还有许多其 他重要的化学键如氢键、二硫键、离子键、酯键、疏水键和范德华力（图 7- 7）5- 6，这些键中的一种或几种都影响蛋白质的吸附过程。尽管不是每 种蛋白质都包含有上述所有键，但是对于任何一种蛋白质由于其固有的氨 基酸结构，在1541cm1（Amide II）和1642cm1（Amide I）附近有较强的 吸收峰。主要蛋白质的分子量主要
3、蛋白质的分子量蛋白质分子量蛋白质分子量胰岛素 细胞色素C RNA酶 溶菌酶 a淀粉酶 血红蛋白（人 ）5734 12393 13683 14300 97600 64500天冬酰胺酶 脲酶 醇脱氢酶 RNA聚合酶 烟草花叶病毒 蛋白255000 483000 150000 880000 40000000几种蛋白质的等电点几种蛋白质的等电点Preliminary measurements on PEPreliminary measurements on PEAdsorptionalAdsorptional isothermisotherm Dependence on ConcentrationDe
4、pendence on ConcentrationAdsorpt i on i sotherm of BSA on PE at pH=5012340100020003000Concentrati on i n Eq.amount adsorbed mg.m- 2Amount adsorbed in Correlation with Area of AII Peak at pH=5y = 0.6241x + 0.1224R2 = 0.9212 01231.02.03.04.05.0amount adsorbedAre a o f pe ak AIIPeak AII area and covera
5、ge ratio Peak AII area and coverage ratio changes with concentrationchanges with concentrationChange of AII peak area due to adsorption and desorption at pH=501230200040006000Initial concentration, ppmAII peak areaAfter adsorptionafter desorption with bufferafter desorption with 1 wt% SDS aqueous so
6、lutionChange of coverage ratio due to adsorption and desorption at pH=500.511.5020004000Initial concentration, ppmcoverage ratioAfter adsorptionafter desorption with bufferafter desorption with 1 wt% SDS aqueous solutionDependence on timeDependence on time0123450200400600800time, minadso rbe d am o
7、u n ts, m g/ st. m e te r00.511.522.5010002000time, minAII peak areaafter adsorptionafter SDS desorptionGeneral General adsorptionaladsorptional stepsstepsnDiffusion of protein molecules from bulk to the interfacenAttachment of protein molecules to active sites on the surfacenReconformation of the s
8、tructure of the protein molecule after adsorption.TimeTime- - FTIR mappingFTIR mapping- 0.50.00.51.01.52.02.53.03.54.04.55.05.56.0Absorbance020406080100120140160180200220祄1000 1500 2000 Wavenumbers (cm- 1)5 mins10 mins20 mins- 1.0- 0.50.00.51.01.52.02.53.03.54.04.55.05.56.0Absorbance0204060801001201
9、40160祄1000 1500 2000 Wavenumbers (cm- 1)0.00.51.01.52.02.53.03.54.04.55.05.56.0Absorbance020406080100120140160180祄1000 1500 Wavenumbers (cm- 1)0.00.51.01.52.02.53.03.54.04.55.05.56.0Absorbance050100150200祄1200 1400 1600 1800 Wavenum bers (cm - 1)40 minsDiffusionalDiffusional speedspeedEffect of rota
10、ting speed on AII peak area at pH=500.511.522.5050100150200250Rotating speedAII peak areaafter adsorptionafter desorption with buffer after SDS desorption22.533.54050100150200250rotating speed, rpmAmount adsorbed, mg/st mete rAdditional testAdditional testEffect of the way that BSA is added on the a
11、dsorption.The condition of the both cases are completely same, but A: the BSA is added one time to make a 2000 ppm solution for adsorption; B-The equal amount of BSA is added 6 times respectively into the equal medium volume at every 4hrs adsorption interval. 00.511.522.5After adsorptionafter buffer
12、 desorptionAfter SDS- desorptionAII peak areaA BpH effectpH effectChange of Amide II area with pH after adsorption at different concentration0.01.02.03.00200040006000Initial concentrationA II A re aph=4.06ph=5.05pH=6.39pH=9.18Change of Amide II area after the adsorbed samples in Fig.11 are desorbed
13、with SDS0.00.20.40.60.81.01.20200040006000Initial concentrationAII Areaph=5.05pH=6.39pH=9.18pH=4.06Temperature effectTemperature effectEffect of temperature on the AII peak area after adsorption of BSA on PE00.511.522.501020304050temperatureA II pe ak are apH=4.06pH=5.05pH=6.39Effect of temperature
14、on the AII peak area aftersds- desorption of BSA on PE00.511.5201020304050temperatureA II pe ak are apH=4.06pH=5.05pH=6.39Salt effect Salt effect Effect of Salt concentration on the AII area00.511.522.500.51NaCl concentration, NAII areaafter adsorption after buffer desorption after sds desorptionAds
15、orption of Adsorption of MyoglobinMyoglobinAII area changes with concentration of BSA and MYo after adsorption0123020004000concentration, ppmAII areaMYO, ph7.41BSA,ph5.05Change of AII peak area due to MYO adsorption and desorption at pH=7.4100.511.5020004000concentration, ppmAII areaafter adsorption
16、after desorptionafter sds desorptionCompetitive adsorptionCompetitive adsorptionAII peak area changes with MYO concentration with total concentration remaining at 2000 ppm00.20.40.60.811.21.41.6010002000MYO concentrationAII peak areaafter adsorptionafter buffer- desorption after SDS- desorptionVariation of the amount adsorbed of MYO after adsorption and SDS- desorption comparison of pure and mix solutions0.000.200.400.600.801.001.201.40050010
