title: Vitamin E induces regular structure and stability of human insulin, more intense than vitamin D3.
abstract: Changes in human environment and lifestyle over the last century have caused a dramatic increase in the occurrence of diabetes. Research of past decades illustrated that vitamin D and E have a key role in the improvement of diabetes by reducing oxidative stress, protein glycosylation, insulin resistance and also improving beta cell function. Binding properties and conformational changes of human insulin upon interaction with vitamins D3and E (α-tocopherol) were investigated by spectroscopy, differential scanning calorimetry (DSC) and molecular dynamic simulation. Tyrosine fluorescence quenching studies indicates changes in the human insulin conformation in the presence of vitamins. Binding constants of vitamins D3and E for human insulin were determined to be 2.7 and 1.5 (×10-5M-1) and the corresponding average numbers of binding sites were determined to be 1.3 and 1.2, respectively. Far- and near-UV circular dichroism studies showed that vitamin E can significantly change the secondary and tertiary structures of human insulin via an increase in the content of α-helix structure. Results of DSC showed that both vitamins D3and E stabilize the structure of human insulin. Molecular dynamic simulation results indicated that vitamin D3decreases the helical and strand structural contents of human insulin, but vitamin E stabilizes more regular secondary structures such as helical and strand structural contents as shown by experimental results.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran. Electronic address: h_soleymani@ut.ac.ir.
authors.forename: Hossein
authors.initials: H
authors.lastname: Soleymani
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran. Electronic address: saboury@ut.ac.ir.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Saboury
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran. Electronic address: moosavi@ibb.ut.ac.ir.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Moosavi-Movahedi
authors.affiliation: Department of Plant Science, Faculty of Life Science, Tarbiat Modares University, Tehran, Iran. Electronic address: fatemehr_67@yahoo.com.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Rahmani
authors.affiliation: Department of Biology, Faculty of Basic Science, Hakim Sabzevari University, Sabzevar, Iran. Electronic address: javadmaleki394@yahoo.com.
authors.forename: Javad
authors.initials: J
authors.lastname: Maleki
authors.affiliation: Research Center for Health Sciences, Department of Occupational Health, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran. Electronic address: yousefinejad@ibb.ut.ac.ir.
authors.forename: Saeid
authors.initials: S
authors.lastname: Yousefinejad
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran. Electronic address: p.maghami@ibb.ut.ac.ir.
authors.forename: Parvaneh
authors.initials: P
authors.lastname: Maghami
mesh_terms: D000595:Amino Acid Sequence; D002152:Calorimetry, Differential Scanning; D002762:Cholecalciferol / Q000737:chemistry*; D002942:Circular Dichroism; D000067493:Dynamic Light Scattering; D006801:Humans; D007328:Insulin / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D000072417:Protein Domains; D055550:Protein Stability; D017433:Protein Structure, Secondary; D013816:Thermodynamics; D014810:Vitamin E / Q000737:chemistry*
chemical_list: D007328:Insulin; D014810:Vitamin E; D002762:Cholecalciferol
keywords: Circular dichroism; Differential scanning calorimetry; Human insulin; Molecular dynamic simulation; Vitamin D(3); Vitamin E