Phosphoglycolate synthesis by human erythrocyte pyruvate kinase
| Autor: | Koji Nakashima, Hiroko Sasaki, Shinya Fujii, Toshio Kaneko, Yoshiki Yoshizaki |
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| Rok vydání: | 1987 |
| Předmět: |
2
3-Diphosphoglycerate Pyruvate dehydrogenase lipoamide kinase isozyme 1 Pyruvate dehydrogenase kinase Erythrocytes Dose-Response Relationship Drug Kinase Pyruvate Kinase Hematology General Medicine Mitogen-activated protein kinase kinase Pyruvate dehydrogenase phosphatase PKM2 Biology Hydrogen-Ion Concentration Diphosphoglyceric Acids Glycolates Enzyme Activation Kinetics Adenosine Triphosphate Biochemistry Fructosediphosphates Humans Kinase activity Phosphorylation Pyruvate kinase |
| Zdroj: | Acta haematologica. 77(2) |
| ISSN: | 0001-5792 |
| Popis: | R2-type pyruvate kinase purified monogeneously from human red cells catalyzes the phosphorylation of glycolate (glycolate kinase). Maximum activation of glycolate kinase was observed at 100 microM fructose-1,6-bisphosphate (Fru-1,6-P2) and at 2 mM glucose-1,6-bisphosphate (Glc-1,6-P2). The Km for ATP was 1.1 mM in the absence of Fru-1,6-P2 and 1.5 mM in the presence of 1 mM Fru-1,6-P2. The Km for glycolate was 20 mM in the absence of Fru-1,6-P2 and 5 mM in the presence of 1.0 mM Fru-1,6-P2. The optimum pH was over 10.5. At the physiological concentrations of Fru-1,6-P2, Glc-1,6-P2 and ATP, the glycolate kinase activity is too low to maintain the reported level of phosphoglycolate (approx. 2-5 microM). It is demonstrated that phosphorylation of glycolate by R2-type pyruvate kinase which is predominant in mature red cells plays no physiological role. The questions whether an unknown pathway for phosphoglycolate synthesis exists or whether there is actually phosphoglycolate in red cells are raised. |
| Databáze: | OpenAIRE |
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