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  • Title
  • CERTIFICATE
  • DECLARATION
  • ACKNOWLEDGEMENT
  • DEDICATION
  • CONTENTS
  • 1 Introduction and Objectives
  • 1.1 Nitric Oxide: A Newly Discovered Messenger Molecule
  • 1.2 Physical and Chemical Properties of NO
  • 1.3 Biosynthesis of NO
  • 1.3.1 Production of NO
  • 1.4 The fate of NO
  • 1.5 Biological Implication of NO
  • 1.6 NO in Pharmacology
  • 1.7 S-Nitrosothiols
  • 1.8 The Chemistry of RSNOs
  • 1.9 Synthesis of RSNO
  • 1.10 Biological importance of RSNOs
  • 1.11 Biochemistry of RSNOs
  • 1.11.1 With metals
  • 1.11.2 With nucleophiles
  • 1.11.3 With heme and non-heme models
  • 1.11.4 With hydrogen peroxide
  • 1.11.5 With Enzymes
  • 1.11.6 With reducing agents
  • a) With ascorbate
  • b) With thiols
  • 1.11.7 With free radicals
  • 1.11.8 Photolytic and thermal decomposition
  • 1.12 Aqueous Radiation Chemistry: Production of Free Radicals.
  • 1.12.1 Radiation Sources
  • 1.12.2 Ionization and excitation
  • 1.12.3 Radiation Technique
  • 1.12.4 Radiolysis of Water
  • 1.12.5 Primary Species and Their Properties
  • a. Hydroxyl radicals (OH) and Oxide radical anion (O-)
  • b. Hydrated electron (e-aq)
  • c. Hydrogen Radical (H}
  • d. Perhydroxyl radical (HO2)
  • e. Hydrogen peroxide (H2O2)
  • 1.12.6 Yields of primary radicals
  • 1.12.7 Secondary radicals
  • 1.13 Photochemistry
  • 1.13.1 Quantum Efficiency or Quantum Yield ( (Φ)
  • 1.13.2 Electronic Energy States
  • 1.13.3 Interaction with Matter
  • 1.13.4 Jablonski Diagram
  • 1.13.5 Types of Photochemical Reactions
  • 1.14 Scope of the work
  • 1.15 Objectives
  • 2 Materials and Methods
  • 2.1 Materials
  • 2.2 Synthesis of RSNO
  • 2.3 Radiation Chemical Studies
  • 2.3.1 Gamma Radiolysis
  • 2.3.2 Pulse Radiolysis
  • A) Linear accelerators
  • 2.3.3 Radiation Dosimetry
  • a) Ceric Sulfate Dosimeter
  • b) Thiocyanate Dosimeter
  • 2.4. Hydroxyl radical induced decomposition of RSNOs
  • 2.4.1 Preparation of RSNO solutions
  • 2.4.2 Thiobarbaturic acid (TBA) assay
  • 2.5. One electron reduction of RSNOs
  • 2.5.1 Preparation of RSNO solutions
  • 2.6. Ultra Violet Light setup
  • 2.6.1. Actinometry
  • 2.7. Sunlight Irradiated Experiments
  • 2.8. Laser flash photolysis setup
  • 2.9. Analytical Instruments
  • 2.9.1 UV-VIS spectrophotometer
  • 2.9.2 High Performance Liquid Chromatography (HPLC)
  • 2.9.3 Gas Chromatography-Mass Spectrometer (GCMS)
  • 2.9.4 pH meter
  • 3 Decomposition Reactions of S-Nitrosothiols Induced by Hydroxyl Radicals
  • 3.1 Introduction
  • 3.2 Determination of Second Order Rate Constants
  • 3.3 OH Induced Decomposition
  • i) Stability of RSNOs
  • ii) Steady State Radiolysis Experiments
  • iii) Pulse Radiolysis Experiments
  • 3.4 Reaction Mechanism
  • 3.5 Conclusion and Biological Significance
  • 4 Decomposition Reactions of S-Nitrosothiols Induced by Hydrated Electron
  • 4.1 Introduction
  • 4.2 Determination of the Second Order Rate Constants by Pulse Radiolysis Technique
  • 4.3 Hydrated Electron Induced Decomposition of RSNOs
  • a) Steady State Analysis
  • b) Pulse Radiolysis Experiments
  • 4.4 Mechanism
  • 4.5 Conclusion and Biological Significance
  • 5 Photo Induced Decomposition of S-Nitrosothiols
  • 5.1 Introduction
  • 5.2 UV light induced decomposition of RSNO
  • 5.2.1 Product Analysis
  • 5.2.2 Quantum yields (Φ)
  • 5.2.3 Measurement of the Rate Constants
  • 5.3 Sunlight Induced Decomposition of RSNOs
  • 5.3.1 Product Analyses
  • 5.3.2 Quantum Yields (Φ?)
  • 5.3.3 Determination of the Rate Constants
  • 5.4 Photochemical release of NO via the formation of thiyl radical intermediate
  • 5.5 Conclusion and biological significance
  • References