Hajar Yaghoobi a and Mojgan Bandehpour b* a Molecular& Cellular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. b Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Keywords: Core protein HbsAg Circular dichroism HIGHLIGHTS • The structure of recombinant protein is very important in vaccine complex with an adjuvant. • The immunity of HCV core and HbsAg proteins could increase in complex with HSP90. • Fluorescence spectroscopy and circular dichroism were used to determine the proteins structure. • Structural data confrmed the hydrophobic properties if proteins changed in complexation with HSP90. * Corresponding Author: Email: m.bandehpour@sbmu.ac.ir (M. Bandehpour) ABSTRACT The secondary structure of recombinant proteins can change through complex formation with other proteins. Here, we have determined the spatial structure of two proteins, including core protein of hepatitis C virus and HbsAg of hepatitis B virus, without the effect of human HSP90 as well as with the effect of this recombinant chaperone. As a result, the increase in intensity from 297.5 to 346.64 was accompanied by different folding and being non-polar protein in complex with the chaperone. HbsAg protein, combined with HSP90, showed a reduction in the maximum peak wavelength from 385 to 369.07 nm. The property of protein of being non-polar and hydrophobic, as well as having an increase in intensity from 200 to 219, indicates the protein folding. The shift from 342 to 337 nm along with blue shift indicates hydrophobic properties and the removal of protein from the water environment. Effect of Human HSP90 on Secondary and Tertiary Structures of Core Protein of Hepatitis C Virus and HbsAg of Hepatitis B Virus Original Research Article Trends in Peptide and Protein Sciences 2016ˏVol. 1ˏ No.2ˏ68-72 Article history: Received: 2 July 2016 Accepted: 13 November 2016 Introduction The structure of the recombinant protein is always very important in vaccine complex with an adjuvant. In our previous project (Bandehpour et al., 2008), we have reached the increased immunity of HCV core and HbsAg proteins in complex with HSP90. HBV is a member of the hepadnavirus family prototype. The membrane proteins of HBV are encoded by the ORF S and located within lipid bilayer membrane of the virus. These proteins are involved in the binding to the receptors, the assembly of virus, and secretion. Three main proteins, L, M and S, were produced from one of the three genes, including pre-S1, pre-S2 and S (Liang, 2009). Six genotypes of HBV were divided into 9 subtypes from A to F in accordance with antigenic indexes of protein S. There was a difference of up to 4% between them. Hepatitis C is very similar to pestiviruses and faviviruses with respect to the genomic and hydrophobicity profles of polypeptides. This virus was divided into a separate strain from the Flaviviridae family. Hepatitis C has positive single-stranded RNA with 9,500 nucleotides. The frst 191 amino acids formed the core protein with molecular weight 19 to 23 kDa (Knipe and Howley, 2013). At the same time, this protein entered the endoplasmic reticulum, and it was translated, and brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by shahrekord university of medical scinces