Matrix ligands are agents for isolating proteins out of dilute crudes by coprecipitating proteins. The ligands have a strong anion sulfonate head which initiates binding to proteins having a positive net charge, ZH+ approximately 5-20. Initial binding tightens protein conformation and starts to squeeze water from conformationally motile proteins. The tails are stackable hydrophobic organic groups, azoaromatic dyes which draw protein-ligand complexes together. Proteins coprecipitate as guests, in the ligand host matrix. In addition to stacking, ligand tails displace water because of their bulk, and lower the average dielectric constant near charged groups, which reinforces the electrostatic component of binding. Matrix ligands protect proteins, scavenge them from dilute crudes (0.01-0.1 per cent protein), and densify coprecipitates. Detergent ions in low concentrations, 10(-4)-10(-5) M also sometimes serve as coprecipitating agents, entangling their tails but probably not stacking. Divalent metal ions, Zn++, sometimes are useful auxiliary agents. Preparative scaleability from crudes is demonstrated starting from 100-200 g of raw peanuts and raw pineapple to coprecipitate a lectin and bromelain enzyme respectively in 1-2 h with 80-90 per cent activity yields. Ligands are released from coprecipitates by shifting the pH and trapping the ligands with exchange resins. Protein conformation tightening in solution is seen by viscosity measurements.

译文

基质配体是通过共沉淀蛋白质从稀原油中分离蛋白质的试剂。配体具有很强的阴离子磺酸根头,可与具有正净电荷(ZH约为5-20)的蛋白质结合。初始结合会拉紧蛋白质构象,并开始从构象运动的蛋白质中挤出水。尾部是可堆叠的疏水有机基团,偶氮芳香族染料,可将蛋白质-配体复合物吸引在一起。蛋白质作为客体在配体宿主基质中共沉淀。除了堆积之外,配体尾部还因为其体积而置换了水,并降低了带电基团附近的平均介电常数,从而增强了结合的静电成分。基质配体可以保护蛋白质,从稀原油中清除蛋白质(蛋白质含量为0.01-0.1%),并浓缩共沉淀物。低浓度10(-4)-10(-5)M的去污剂离子有时还充当共沉淀剂,缠住它们的尾巴,但可能不会堆积。二价金属离子Zn有时是有用的辅助剂。从100-200 g的粗花生和菠萝开始,可在1-2小时内分别沉淀出凝集素和菠萝蛋白酶,具有80-90%的活性收率,证明了从原油可制备的可扩展性。通过改变pH值并用交换树脂捕获配体,从共沉淀物中释放出配体。通过粘度测量可以看出溶液中的蛋白质构象变紧。

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