文献类型：期刊文献

英文题名：Electrostatic Selectivity in Protein-Nanoparticle Interactions

作者：Chen, Kaimin[1];Xu, Yisheng[2];Rana, Subinoy[2];Miranda, Oscar R.[2];Dubin, Paul L.[2];Rotello, Vincent M.[2];Sun, Lianhong[3,4];Guo, Xuhong[1]

机构：[1]E China Univ Sci & Technol, Sch Chem Engn, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Univ Massachusetts, Dept Chem, Amherst, MA 01003 USA;[3]Univ Massachusetts, Dept Chem Engn, Amherst, MA 01003 USA;[4]Univ Sci & Technol China, Sch Life Sci, Hefei 230027, Anhui, Peoples R China

年份：2011

卷号：12

期号：7

起止页码：2552

外文期刊名：BIOMACROMOLECULES

收录：;EI(收录号：20112914149941);WOS:【SCI-EXPANDED(收录号:WOS:000292617700016)】；

基金：Support from NSF (Grant CBET-0966923; L.S. (PI) & P.L.D.), from NIH (GM077173; V.M.R), and the China Scholarship Council (K.C.) are acknowledged. We thank Dr. Christophe Schmitt (Nestle, Lausanne, Switzerland) for the gift of BLG samples.

语种：英文

外文关键词：Calorimeters - Dynamic light scattering - Gold nanoparticles - Isotherms - Calorimetry - Ionic strength - Body fluids - Proteins - Titration

摘要：The binding of bovine serum albumin (BSA) and beta-lactoglobulin (BLG) to TTMA (a cationic gold nanoparticle coupled to 3,6,9,12-tetraoxatricosan-1-aminium, 23-mercapto-N,N,N-trimethyl) was studied by high-resolution turbidimetry (to observe a critical pH for binding), dynamic light scattering (to monitor particle growth), and isothermal titration calorimetry (to measure binding energetics), all as a function of pH and ionic strength. Distinctively higher affinities observed for BLG versus BSA, despite the lower pI of the latter, were explained in terms of their different charge anisotropies, namely, the negative charge patch of BLG. To confirm this effect, we studied two isoforms of BLG that differ in only two amino acids. Significantly stronger binding to BLGA could be attributed to the presence of the additional aspartates in the negative charge domain for the BLG dimer, best portrayed in DelPhi. This selectivity decreases at low ionic strength, at which both isoforms bind well below pI. Selectivity increases with ionic strength for BLG versus BSA, which binds above pI. This result points to the diminished role of long-range repulsions for binding above pI. Dynamic light scattering reveals a tendency for higher-order aggregation for TTMA-BSA at pH above the pI of BSA, due to its ability to bridge nanoparticles. In contrast, soluble BLG-TIMA complexes were stable over a range of pH because the charge anisotropy of this protein at makes it unable to bridge nanoparticles. Finally, isothermal titration calorimetry shows endoenthalpic binding for all proteins: the higher affinity of TTMA for BLGA versus BLGB comes from a difference in the dominant entropy term.