Membrane-bound phenylalanine hydroxylase of human liver
| Autor: | Valery V. Chestkov, Alexey V. Laptev, Sergey S. Shishkin |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Adult
Male Phenylalanine hydroxylase Protein subunit Phenylalanine Autoantigens Antigen medicine Humans Aged chemistry.chemical_classification Hepatology biology Immunochemistry Membrane Proteins Phenylalanine Hydroxylase Metabolism Middle Aged Molecular biology medicine.anatomical_structure Enzyme Biochemistry chemistry Liver Cytoplasm Hepatocyte biology.protein Electrophoresis Polyacrylamide Gel Female |
| Zdroj: | Journal of hepatology. 16(1-2) |
| ISSN: | 0168-8278 |
| Popis: | Phenylalanine hydroxylase (EC 1.14.16.1) antigen and activity have been identified among proteins extracted with a buffer containing 0.4% Triton X-100 from adult human liver bioptate fraction, which was sedimented at 105 000 × g ( n =4). This enzyme fraction was designated as a ‘membrane-bound form of phenylalanine hydroxylase'. It amounted to 5–15% of phenylalanine hydroxylase activity and 15–25% of phenylalanine hydroxylase antigen content. After immunoblotting two-dimensional gels, the soluble (cytoplasmic) form of phenylalanine hydroxylase antigen displayed three spots: one spot corresponded to the L-subunit with a molecular weight of 55 000, the two other spots corresponded to the H-subunit with a molecular weight of 57 000. Only the L-subunit was revealed in the membrane-bound enzyme form. Both phenylalanine hydroxylase activity and antigen were also demonstrated in extracts from human embryonic livers ( n =7). However, in this case the membrane-bound phenylalanine hydroxylase amounted to 85% of the antigen content. Subunit compositions of the enzymes were similar in adult and embryonic livers. The differences in the subunit compositions and enzyme activities of membrane-bound and cytoplasmic forms of phenylalanine hydroxylase in adults and embryos may be due to other functions of this enzyme in the hepatocyte membrane. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|