title: In silicodesigning of a new cysteine analogue of hirudin variant 3 for site specific PEGylation.
abstract: Hirudin is an anticoagulant agent of the salivary glands of the medicinal leech. Recombinant hirudin (r-Hir) displays certain drawbacks including bleeding and immunogenicity. To solve these problems, cysteine-specific PEGylation has been proposed as a successful technique. However, proper selection of the appropriate cysteine residue for substitution is a critical step. This study has, for the first time, used a computational approach aimed at identifying a single potential PEGylation site for replacement by cysteine residue in the hirudin variant 3 (HV3). Homology modeling (HM) was performed using MODELLER. All non-cysteine residues of the HV3 were replaced with the cysteine. The best model was selected based on the results of discrete optimized protein energy score, PROCHECK software, and Verify3D. The receptor binding was investigated using protein-protein docking by ClusPro web tool which was then visualized using LigPlot+ software and PyMOL. Finally, multiple sequence alignment (MSA) using ClustalW software and disulfide bond prediction were performed. According to the results of HM and docking, Q33C, which was located on the surface of the protein, was the best site for PEGylation. Furthermore, MSA showed that Q33 was not a conserved residue and LigPlot+ software showed that it is not involved in the hirudin-thrombin binding pocket. Moreover, prediction softwares established that it is not involved in disulfide bond formation. In this study, for the first time, the utility of thein silicoapproach for creating a cysteine analogue of HV3 was introduced. Our study demonstrated that the substitution of Q33 by cysteine probably has no effect on the biological activity of the HV3. However, experimental analyses are required to confirm the results.
authors.affiliation: Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, I.R. Iran.
authors.forename: Seyed Mehdi
authors.initials: SM
authors.lastname: Sajjadi
authors.affiliation: Molecular Medicine Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, I.R. Iran.
authors.forename: Hamzeh
authors.initials: H
authors.lastname: Rahimi
authors.affiliation: Hematology, Oncology and Stem Cell Transplantation Research Center, Tehran University of Medical Sciences, Tehran, I.R. Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Mohammadi
authors.affiliation: Rasoul Akram Medical Center, Iran University of Medical Sciences, Tehran, I.R. Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Faranoush
authors.affiliation: Biotechnology Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, I.R. Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Mirzahoseini
authors.affiliation: Thrombosis and Homeostasis Research Center, Imam Khomeni Hospital Complex, Tehran University of Medical Sciences, Tehran, I.R. Iran.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Toogeh
keywords: Hirudin variant 3; In silico; PEGylation