title: Molecular aspects of the interaction of spermidine and α-chymotrypsin.
abstract: Polyamines such as spermidine are essential for survival. The purpose of the present study was to investigate how spermidine could influence the conformation, thermal stability and the activity of α-chymotrypsin. The influence of spermidine on the structure and stability of α-Chymotrypsin (α-Chy) explored using different spectroscopy method and molecular docking simulations. The stability and activity of α-Chy were increased in the presence of spermidine. Increasing of the α-Chy absorption in the presence of spermidine was as a result of the formation of a spermidine - α-Chy complex. The results of fluorescence spectroscopic measurements suggested that spermidine has a vigorous ability to quench the intrinsic fluorescence of α-Chy through the dynamic quenching procedure. Near and Far-UV CD studies also confirmed the transfer of aromatic residues to a more flexible environment. The absorption increasing of α-Chy in the presence of spermidine was as a result of the formation of spermidine - α-Chy complex. Molecular docking results also revealed the presence of one binding site with a negative value for the Gibbs free energy of the binding of spermidine to α-Chy. Further, the docking study revealed that van der Waals interactions and hydrogen bonds play a main role in stabilizing the complex.
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 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 Chimistry, Faculty of Science, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran.
authors.forename: Ali Kazemi
authors.initials: AK
authors.lastname: Babaheydari
authors.affiliation: Department of Biology, Faculty of Sciences, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran.
authors.forename: Fatame
authors.initials: F
authors.lastname: Raisi
authors.affiliation: Young Researchers and Elites Club, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Heidari
mesh_terms: D002918:Chymotrypsin / Q000378:metabolism*; D002942:Circular Dichroism; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013095:Spermidine / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties; D044366:Transition Temperature
chemical_list: D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D013095:Spermidine
keywords: Docking simulations; Dynamic quenching; Spectroscopic techniques; Thermal stability; α-Chymotrypsin