Biosynthesis of selenophosphate
| Autor: | Gerard M. Lacourciere |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Molecular Sequence Data
Clinical Biochemistry Biology medicine.disease_cause Biochemistry Phosphates Mice chemistry.chemical_compound Biosynthesis ATP hydrolysis Escherichia coli medicine Animals Drosophila Proteins Humans Amino Acid Sequence Threonine Selenium Compounds chemistry.chemical_classification Bacteria Sequence Homology Amino Acid Phosphotransferases Mutagenesis General Medicine Molecular biology Amino acid Enzyme Models Chemical chemistry Molecular Medicine Specific activity Sequence Alignment |
| Zdroj: | BioFactors. 10:237-244 |
| ISSN: | 1872-8081 0951-6433 |
| DOI: | 10.1002/biof.5520100222 |
| Popis: | Selenophosphate synthetase, the product of the selD gene, produces the highly active selenium donor, monoselenophosphate, from selenide and ATP. Positional isotope exchange experiments have shown hydrolysis of ATP occurs by way of a phosphoryl-enzyme intermediate. Although, mutagenesis studies have demonstrated Cys17 in the Escherichia coli enzyme is essential for catalytic activity the nucleophile in catalysis has not been identified. Recently, selenophosphate synthetase enzymes have been identified from other organisms. The human enzyme which contains a threonine residue corresponding to Cys17 in the E. coli enzyme, has been overexpressed in E. coli. The purified enzyme shows no detectable activity in the in vitro selenophosphate synthetase assay. In contrast, when the human enzyme is expressed to complement a selD mutation in E. coli, in the presence of 75Se, incorporation of 75Se into bacterial selenoproteins is observed. The inactive purified human enzyme together with the very low determined specific activity of the E. coli enzyme (83 nmol/min/mg) suggest an essential component for the formation of selenophosphate has not been identified. |
| Databáze: | OpenAIRE |
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