Glucose oxidase (GOx) is a flavoenzyme having applications in medical industries Here, the structure of GOxin the presence ofmonovalent Cation (NaCl) has been studied. MD simulations were carried out by GROMACS 5.0.4 with a GROMOS 43a1 forcefiled. Parameters for flavin adenine dinucleotide (FAD) were taken from the work of van den Berg et al. and protein(pdb code: 1GPE) was placed in a cubic box center consisting SPC216 water molecules. About 2000NaCl were placed inthe box.Simulations were performed for 100 ns with a timestep of dt = 0.002 ps[1-3].According tormsf analysis some secondary structures of GOx are destructed while some structures are formed on treatment with NaCl. The analysis of active site structure in chain A of GOx revealed that hydrogen bonding between His563 at N 2 and Glu416 O 2(5.2 Aº) is increased to the high value in GOx-NaCl which is deviated from crystal (2.5 Aº). The flavin O4 is connected by hydrogen bonds to the backbone N atoms of Ser114 (7.5 Aº) and Gly112 (8.3 Aº) in GOx-NaCl which have high value in comparison with the crystal (3Aº and 3.3Aº forSer114 and Gly112, respectively)[4].These results are in agreement with experimental dataaboutthe structure of GOx [5]. NaCl could enter the active pocket of GOx,leading to a change in the orientation of FAD and an alteration in conformation of GOx.The structural details would be important for rational enzyme design.

Keywords