Kinetic Analysis and Tissue Distribution of Human D-Glycerate Dehydrogenase/Glyoxylate Reductase and its Relevance to the Diagnosis of Primary Hyperoxaluria Type 2
| Autor: | Gill Rumsby, C F Giafi |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
030213 general clinical medicine
Clinical Biochemistry Glyoxylate cycle 030209 endocrinology & metabolism Dehydrogenase Biology 03 medical and health sciences 0302 clinical medicine medicine Humans Tissue Distribution Glycerate dehydrogenase Glyoxylate reductase chemistry.chemical_classification Kidney medicine.diagnostic_test Catabolism Reproducibility of Results General Medicine Hydrogen-Ion Concentration Alcohol Oxidoreductases Kinetics medicine.anatomical_structure Enzyme Biochemistry chemistry Liver biopsy Hyperoxaluria Primary Linear Models Carbohydrate Dehydrogenases |
| Zdroj: | Annals of Clinical Biochemistry: International Journal of Laboratory Medicine. 35:104-109 |
| ISSN: | 1758-1001 0004-5632 |
| DOI: | 10.1177/000456329803500114 |
| Popis: | The enzyme D-glycerate dehydrogenase (D-GDH; EC 1.1.1.29), which is also believed to have glyoxylate reductase (GR; EC 1.1.1.26/79) activity, plays a role in serine catabolism and glyoxylate metabolism and deficiency of this enzyme is believed to be the cause of primary hyperoxaluria type 2 (PH2).The pH optima and kinetic parameters of D-GDH and GR in human liver have been determined and assays developed for their measurement. Maximal activities were observed at pH 6.0, 8.0 and 7.6 for the D-GDH forward, D-GDH reverse and GR reactions, respectively. The apparent Km values for the substrates in these reactions were as follows: D-GDH forward reaction, 0.5 mmol/L hydroxypyruvate and 0.08 mmol/L NADPH; D-GDH reverse reaction, 20 mmol/L D-glycerate and 0.03 mmol/L NADP and for the GR reaction 1.25 mmol/L glyoxylate and 0.33 mmol/L NADPH. The forward D-GDH and GR assays were adopted for routine use, the low activity of the reverse D-GDH reaction being of little use for routine analyses.D-GDH and GR activity in 13 normal livers ranged from 350–940 nmol per min per mg protein (median 547) and 129–209 nmol per min per mg protein (median 145), respectively. D-GDH activity in kidney, lymphocytes and fibroblasts fell within the range of values seen in the liver but GR activity was approximately 30% in the kidney and barely detectable in lymphocytes and fibroblasts. Analysis of liver and lymphocyte samples from patients with PH2 showed that GR activity was either very low or undetectable while D-GDH activity was reduced in liver but within the normal range in lymphocytes. These results suggest that there is more than one enzyme with D-GDH activity in human tissues but only one of these has significant GR activity. We conclude that a definitive diagnosis of PH2 requires measurement of GR and D-GDH in a liver biopsy. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|