title: A spectroscopic and thermal stability study on the interaction between putrescine and bovine trypsin.
abstract: The interaction of putrescine with bovine trypsin was investigated using steady state thermal stability, intrinsic fluorescence, UV-vis spectroscopy, far and near- UV circular dichroism and kinetic techniques, as well as molecular docking. The Stern-Volmer quenching constants for the trypsin- putrescine complex were calculated revealing that putrescine interacted with trypsin via the static fluorescence quenching. The enthalpy and entropy change values and the molecular docking technique revealed that hydrogen bonds and van der Waals forces play a major role in the binding process. Upon putrescine conjugation, the Vmaxvalue and the kcat/Kmvalues of the enzyme was increased. The results of UV absorbance, circular dichroism and fluorescence techniques demonstrated that the micro environmental changes in trypsin were induced by the binding of putrescine, leading to changes in its secondary structure. The thermal stability of trypsin- putrescine complex was enhanced more significantly, as compared to that of the native trypsin. The increased thermal stability of trypsin- putrescine complex might be due to the lower surface hydrophobicity and the higher hydrogen bond formation after putrescine modification, as reflected in the increase of UV absorbance and the quenching of fluorescence spectra. It was concluded that the binding of putrescine changed trypsin structure and function.
authors.affiliation: Department of Biology, Faculty of Science, University of Payam Noor, Iran.
authors.forename: Lida
authors.initials: L
authors.lastname: Momeni
authors.affiliation: Department of Biology, Faculty of Science, University of Shahrekord, Shahrekord, P.O. Box 115, Iran. Electronic address: b_shareghi@yahoo.com.
authors.forename: Behzad
authors.initials: B
authors.lastname: Shareghi
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Saboury
authors.affiliation: Department of Biology, Faculty of Science, University of Shahrekord, Shahrekord, P.O. Box 115, Iran.
authors.forename: Sadegh
authors.initials: S
authors.lastname: Farhadian
authors.affiliation: Department of Biology, Faculty of Sciences, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran.
authors.forename: Fateme
authors.initials: F
authors.lastname: Reisi
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D002417:Cattle; D019277:Entropy; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D062105:Molecular Docking Simulation; D011485:Protein Binding; D011487:Protein Conformation; D011700:Putrescine / Q000737:chemistry*; D014357:Trypsin / Q000737:chemistry*
chemical_list: D014357:Trypsin; D011700:Putrescine
keywords: Circular dichroism; Fluorescence spectroscopy; Molecular docking; Putrescine; Trypsin; UV–vis spectroscopy