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Selenium-Thioredoxin Reductase Studied by Semisynthesis

硒硫氧还蛋白还原酶的半合成研究

基本信息

批准号：
7932419
负责人：
ROBERT J HONDAL
金额：
$ 7.76万
依托单位：
UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-30 至 2011-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7932419
关键词：
Active Sites Adopted Affect Alkenes Amides Amino Acids Arthritis Biological Assay C-terminal Chemistry Cloning Code Codon Nucleotides Cysteine Development Disease Disulfides Drug Delivery Systems Enzymes Glycine Goals Ligation Malaria Malignant Neoplasms Measures Mediating Messenger RNA Methods Modeling Molecular Conformation Mutate Oxidation-Reduction Oxidoreductase Pan Genus Peptides Principal Investigator Procedures Process Proteins Reaction Recombinants Role Selenium Selenocysteine Source Structure Substrate Specificity Sulfhydryl Compounds System Technology Terminator Codon Testing Therapeutic Thioredoxin Vertebral column carboxyl group cyclocystine design disulfide bond disulfide compound enzyme mechanism human TXN protein in vivo inhibitor/antagonist intein mutant novel programs protein expression pyridine nucleotide research study small molecule synthetic peptide thioredoxin reductase

项目摘要

DESCRIPTION (provided by applicant): Mammalian thioredoxin reductases are pyridine nucleotide-disulfide oxidoreductases that contain the unusual amino acid selenocysteine. In vivo, selenocysteine is coded in the mRNA by a UGA codon (normally a stop codon). This makes expression of these proteins in heterologous systems difficult. A second remarkable feature of the enzyme is that it utilizes a Se-S bond between adjacent residues in the catalytic cycle. Formation of this bond results in an 8-membered ring structure, and requires that the intervening peptide bond between neighboring cysteine and selenocysteine residues adopt a cis configuration. It is the major hypothesis of this proposal that the enzyme uses the catalytic power of adjacent cysteine and selenocysteine residues in a cis configuration to catalyze reduction of target disulfides. The cis configuration is expected to be more reducing because of the high local concentration of thiol this geometry imposes on the active-site. This proposal utilizes a semisynthetic system for studying the enzyme mechanism. This system divides the protein into two modules, one protein module, and a synthetic peptide containing selenocysteine. This semisynthetic approach to studying thioredoxin reductase and other selenocysteine-containing proteins is novel and unique. This semisynthetic system can be used to generate the wild-type protein and to insert peptide bond isosteres that restrict the geometry of the peptide bond. These isosteres allow for the study of the enzyme mechanism in great detail. The semisynthetic system also permits structure-function studies to be explored by using the method of peptide complementation. Model disulfide compounds that form an 8-membered ring will be synthesized. The redox potentials of these model compounds will be correlated to their backbone geometry. The redox potential of the catalytic disulfide bond of TR (S replaces Se) will be measured and correlated to the model compounds to determine the geometry of the peptide bond in the enzyme active-site. The importance of the thioredoxin system in disease processes such as cancer, arthritis, and malaria gives impetus to the study of the enzyme mechanism for the development of potential therapeutic inhibitors.

描述（由申请人提供）：