Selenium and amino acid composition of selenoprotein P, the major selenoprotein in rat serum
| Autor: | Raymond F. Burk, Jinming Yang, Kristina E. Hill, R. Read, I S Palmer, T. Bellew |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
inorganic chemicals
chemistry.chemical_classification integumentary system GPX3 Selenocysteine Selenoprotein P chemistry.chemical_element Cell Biology Biochemistry Molecular biology chemistry.chemical_compound chemistry Affinity chromatography Selenoprotein Molecular Biology Histidine Selenium Cysteine |
| Zdroj: | Journal of Biological Chemistry. 265:17899-17905 |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/s0021-9258(18)38248-6 |
| Popis: | Selenoprotein P is the second plasma selenoprotein to be purified. It is a glycoprotein and has been shown to be distinct from plasma glutathione peroxidase. This study characterizes selenoprotein P further. Deglycosylation of the protein shifts its migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis from Mr 57,000 to Mr 43,000, indicating it has a substantial carbohydrate component. Measurement of selenium indicates a selenium content of 7.5 +/- 1.0 atoms/molecule based on a polypeptide weight of 43,000. Amino acid analysis accounts for all the selenium as selenocysteine. The protein is also rich in cysteine (17 residues) and histidine (23 residues). Fragmentation of selenoprotein P by trypsin and by cyanogen bromide produces peptides with varying selenium content. This indicates that selenium-rich regions of the protein exist. The concentration of selenoprotein P determined by radioimmunoassay in serum from control rats is 26.3 +/- 4.5 micrograms/ml and in serum from selenium-deficient rats it is 2.7 +/- 0.8 micrograms/ml. Depletion of selenoprotein P from control serum using an immunoaffinity column indicates that over 60% of serum selenium in the rat is contained in this protein. These results demonstrate that selenoprotein P is the major form of selenium in rat serum. It is the first selenoprotein described which has more than one selenium atom/polypeptide chain. |
| Databáze: | OpenAIRE |
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