title: Role of peroxynitrite induced structural changes on H2B histone by physicochemical method.
abstract: Histones are small highly conserved cationic proteins which bind DNA and remain confined in the nucleus. These histones are quite vulnerable to oxidizing and nitrating agents. Peroxynitrite is a powerful oxidant and nitrating agent present in the biological system. In this study, peroxynitrite-induced nitration and oxidation of H2B was assessed by various physicochemical techniques. The carbonyl content and dityrosine were markedly elevated in peroxynitrite-modified H2B histone as compared to the native histone. Cross-linking of H2B was evident on polyacrylamide gel electrophoresis. 3-Nitrotyrosine was present only in peroxynitrite-modified H2B revealed by HPLC. The results showed that peroxynitrite-mediated nitration and oxidation in H2B histone exhibited hyperchromicity, decrease of tyrosine fluorescence accompanied by increase in ANS-binding specific fluorescence, loss of β-sheet structure, appearance of new peak in FT-IR, increase in melting temperature and also loss of α-helix to produce a partially folded structure in comparison to intrinsically disordered structure of native H2B histone. We concluded that the H2B histone, a constituent of core histones, is highly sensitive to peroxynitrite and can adopt different structures under nitrosative and oxidative stress in order to protect the packaged DNA from the deleterious insult of peroxynitrite.
authors.affiliation: Department of Biosciences, Jamia Millia Islamia, New Delhi, India. Electronic address: asad1amu@gmail.com.
authors.forename: M Asad
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Department of Biochemistry, Jawaharlal Nehru Medical College, A.M.U., Aligarh, India.
authors.forename: Khursheed
authors.initials: K
authors.lastname: Alam
authors.affiliation: Department of Biochemistry, Jawaharlal Nehru Medical College, A.M.U., Aligarh, India.
authors.forename: Kiran
authors.initials: K
authors.lastname: Dixit
authors.affiliation: Department of Biosciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: M Moshahid A
authors.initials: MM
authors.lastname: Rizvi
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006657:Histones / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D030421:Peroxynitrous Acid / Q000737:chemistry* / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects*; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D006657:Histones; D030421:Peroxynitrous Acid; D014443:Tyrosine; C007543:dityrosine
keywords: Dityrosine; Histone H2B; Nitrotyrosine; Peroxynitrite