Iranian Nanotechnology Society International Journal of Nanoscience and Nanotechnology 1735-7004 13 2 2017 05 01 Comparative Studies on the Interaction of ‎Proteinase-K with Fe2O3, Fe3O4 and SiO2 ‎Nanoparticles 187 194 25617 EN E. Yadollahi Department of Biology, University of Shahrekord, P.O. Box: 115, Shahrekord, I. R. of ‎Iran.‎ B. Shareghi Department of Biology, University of Shahrekord, P.O. Box: 115, Shahrekord, I. R. of ‎Iran.‎ M. Salavati Institute of Nano Science and Nano Technology, University of Kashan, P.O. Box 87317-‎‎51167, Kashan, I. R. Iran.‎ Journal Article 2015 04 12 <em>   The interaction of </em><em>Fe₂O₃, Fe₃O₄ and SiO₂ nanoparticles with proteinase K activity </em><em>was investigated using UV–vis spectroscopy. </em><em>Proteinase</em><em> K EC (3.4.21.14) is a member of serine protease family, which is produced from fungus Tritirachum album Limber.</em><em>The effects of nanoparticles on proteinase K activity were studies at 40˚C in pH 7.0 using sodium phosphate as buffer. It was found that in the presence of nano-Fe₂O₃ and nano-Fe₃O₄, V_max was decreased but K_m was constant. This results indicated that nano-Fe₂O₃ and nano-Fe₃O₄ acted as noncompetitive inhibitors. In the presence of nano-SiO₂ the amount of K_m increased but V_max decreased, that showed nano-SiO₂ acted as a mixed inhibitor. The dissociation constant (K_i) value for binding nano-Fe₂O₃, nano-Fe₃O₄ to proteinase K was equal to 11µM and 8.5µM respectively that indicated the binding of nano-Fe₃O₄ to the enzyme was stronger than nano-Fe₂O₃. The K_I and K_i value for nano-SiO₂ was 22.5µM and 8µM respectively.</em> https://www.ijnnonline.net/article_25617_694a6dc002be509353ef2c5dd874dfab.pdf