Influence of the Global Charge of the Protein on the Stability of Lysozyme鈥揂uNP Bioconjugates

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• 作者：Betzhy C谩rdenas ; Guadalupe S谩nchez-Obrero ; Rafael Madue帽o ; Jos茅 M. Sevilla ; Manuel Bl谩zquez ; Teresa Pineda
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：September 25, 2014
• 年：2014
• 卷：118
• 期：38
• 页码：22274-22283
• 全文大小：411K
• ISSN：1932-7455

文摘

The relevant biological information to take into account the design of bionanoconjugates is the structural organization of the proteins that interact with a metallic nanoparticle and form a protein corona. We have studied the interaction of the protein lysozyme (LYZ) with gold nanoparticles (AuNPs) protected by citrate, 6-mercaptopurine, and 蠅-mercaptoundecanoic acid monolayers in aqueous solution in a wide pH range. The bioconjugates are stable at pH higher than the isoelectric point (pI) of LYZ. At lower pH, flocculation occurs possibly by interactions between the exposed positive charges of the protein. The modification of the Lys residues of the protein by either succinylation or phosphopyridoxylation brings about important changes in the bioconjugates鈥?flocculation behavior. By considering the location of the modified residues in the three-dimensional structure of the protein, a different orientation upon binding in comparison to that of the native protein is proposed. Finally, the high fluorescence quenching observed in the titration experiments of the bioconjugates is discussed in terms of an amplification of the quenching efficiency by energy transfer on the self-assembled protein film and a severe effect of fluorofore interactions of the proteins attached to the nanoparticle surface.