tailieunhanh - Báo cáo khoa học: The effect of zinc oxide nanoparticles on the structure of the periplasmic domain of the Vibrio cholerae ToxR protein

Proteins adsorbed on nanoparticles (NPs) are being used as biosensors and in drug delivery. However, our understanding of the effect of NPs on the structure of proteins is still in a nascent state. In this work we report the unfolding behavior of the periplasmic domain of the ToxR protein (ToxRp) of Vibrio choleraeon zinc oxide (ZnO) nanoparticles with a diam-eter of nm. | The effect of zinc oxide nanoparticles on the structure of the periplasmic domain of the Vibrio cholerae ToxR protein Tanaya Chatterjee1 Soumyananda Chakraborti1 Prachi Joshi2 Surinder P Singh3 Vinay Gupta4 and Pinak Chakrabarti1 1 Department of Biochemistry Bose Institute Kolkata India 2 NationalPhysicalLaboratory New Delhi India 3 Department of Engineering Science and Materials University of Puerto-Rico Mayaguez USA 4 Department of Physics and Astrophysics University of Delhi New Delhi India Keywords nanoparticle-protein interaction protein unfolding by nanoparticle ToxR protein Vibrio choleras zinc oxide nanoparticle Correspondence Department of Biochemistry Bose Institute P-1 12 CIT Scheme VIIM Kolkata 700054 India Fax 91 33 2355 3886 Tel 91 33 2569 3253 E-mail pinak@ Received 7 April2010 revised 24 June 2010 accepted 3 August 2010 doi Proteins adsorbed on nanoparticles NPs are being used as biosensors and in drug delivery. However our understanding of the effect of NPs on the structure of proteins is still in a nascent state. In this work we report the unfolding behavior of the periplasmic domain of the ToxR protein ToxRp of Vibrio cholerae on zinc oxide ZnO nanoparticles with a diameter of nm. This protein plays a crucial role in regulating the expression of several virulence factors in the pathogenesis of cholera. Thermodynamic analysis of the equilibrium of unfolding induced both by urea and by guanidine hydrochloride GdnHCl and measured by fluorescence spectroscopy revealed a two-state process. NPs increased the susceptibility of the protein to denaturation. The midpoints of transitions for the free and the NP-bound ToxRp in the presence of GdnHCl were and M respectively whereas for urea denaturation the values were and M respectively. Far-UV CD spectra showed a significant change in the protein conformation upon binding to ZnO NPs which was characterized by a substantial decrease in the