title: Molecular investigation on the interaction of spermine with proteinase K by multispectroscopic techniques and molecular simulation studies.
abstract: The alteration in structure, function and stability of proteinase K in the presence of spermine was investigated using spectroscopic methods and simulation techniques. The stability and enzyme activity of proteinase K-spermine complex were significantly enhanced as compared to that of the pure enzyme. The increase in the value of Vmaxand the catalytic efficiency of Proteinase K in presence of spermine confirmed that the polyamine could bring the enzyme hyperactivation. UV-vis spectroscopy, intrinsic fluorescence and circular dichroism methods demonstrated that the binding of spermine changed the microenvironment and structure of proteinase K. The fluorescence studies, showing that spermine quenched the intensity of proteinase K with static mechanism. Thermodynamic parameters analysis suggested that hydrogen bond and van der Waals forces play a key role in complex stability which is in agreement with modeling studies. The CD spectra represented the secondary structure alteration of proteinase K with an increase in α-helicity and a decrease in β-sheet of proteinase K upon spermine conjugation. The molecular simulation results proposed that spermine could interact with proteinase K spontaneously at single binding site, which is in agreement with spectroscopic results. This agreement between experimental and theoretical results may be a worth method for protein-ligand complex studies.
authors: Department of Biology, Faculty of Science, University of Shahrekord, Shahrekord, P.O. Box 115, Iran.
authors: Mansoore
authors: M
authors: Hosseini-Koupaei
authors: Department of Biology, Faculty of Science, University of Shahrekord, Shahrekord, P.O. Box 115, Iran. Electronic address: b_shareghi@yahoo.com.
authors: Behzad
authors: B
authors: Shareghi
authors: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran.
authors: Ali Akbar
authors: AA
authors: Saboury
authors: Department of Chemistry, Isfahan University of Technology, Isfahan, Iran.
authors: Fateme
authors: F
authors: Davar
mesh_terms: D020134:Catalytic Domain; D002942:Circular Dichroism; D019286:Endopeptidase K / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013096:Spermine / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D005656:Fungal Proteins; D013096:Spermine; D019286:Endopeptidase K
keywords: Catalytic activity; Circular dichroism; Fluorescence spectroscopy; Molecular simulation; Proteinase K; Spermine