Application Of Biocompatible Reactions For Studying Protein Oxidative Modifications

The reactive oxygen species(ROS)and reactive nitrogen species(RNS)are unavoidable metabolites in the biological system,which have high reactivity and can trigger the oxidative modifications of protein.The reversible oxidative modifications of thiols,such as forming disulfides(RS-SR'),nitrosothiols(RS-NO)and sulfenic acids(RSOH),can be reduced to thiols.These reversible redox reactions of biological thiols form the fundamental of redox regulation.The protein tyrosine residue may also be oxidized to 3-nitrotyrosine(3-NT)by RNS.3-NT,spawned a large number of studies among science researchers,has been suggested that it can signify as biomarkers of RNS in vivo and related to some neurodegenerative diseases,such as Alzheimer`s and Parkinsonism syndrome.This thesis focuses on using the biocompatible chemical reactions to study protein oxidative modifications,including reversible thiol modifications and protein tyrosine nitration.The main contents are summarized as followsChapter 1: A brief introduction of the protein modifications by biocompatible chemical reactions was presented.Then the generation of ROS and RNS in biological systems and their oxidative modifications to proteins was specifically illustrated.In addition,we also summarized the approaches used to determine the modifications of the biological thiols and protein tyrosine nitration.Chapter 2: On the basis of nucleophilic aromatic substitution reaction,a series of naphthalimide derivatives was designed and synthesized.After the initial screening,the compound MSBN was evaluated as the best response to biological thiols.MSBN was further applied to determine various reversible protein thiol modifications.In addition,a mass-tagged probe MSBN-TPP was constructed and successfully applied to assay the redox states of a small redox protein thioredoxin.Chapter 3: 3-NT is easily reduced to 3-aminotyrosine,which readily reacts with aniline under potassium hexacyanoferrate(III)oxidation.Based on these reactions,the p-methylaniline derivatives with tags(RB-aniline and Biotin-aniline)were designed and synthesized.Then we have successfully used RB-aniline and Biotin-aniline to detect the 3-NTin complex biological systems.Chapter 4: In this chapter,the 3-NT was transferred to 3-azide tyrosine,which was trapped by the strain-promoted azide-alkyne cycloaddition(SPAAC)reaction.Compared to the methods described in the Chapter 3,this clickable transformation of 3-NT gives higher yield and avoiding using the oxidation conditions.A small probe RB-DIBO was prepared and applied to detect the 3-NT-containing proteins.