| Autor: |
Jung Ahn M; Department of Biochemistry and Health Science, College of Natural Sciences, Changwon National University, Sarimdong, Changwon City, Kyungnam 641-773, South Korea., Young Moon J, Ook Kang D, Cho YK |
| Jazyk: |
angličtina |
| Zdroj: |
Biochimie [Biochimie] 2004 Feb; Vol. 86 (2), pp. 151-6. |
| DOI: |
10.1016/j.biochi.2003.11.014 |
| Abstrakt: |
Maximum activity for phosphorylating C(2)-OH of the ascorbic acid was observed at the time of 16 h incubation from the culture of Flavobacterium devorans ATCC 10829. The enzyme was purified 1.178-fold, via ammonium sulfate fractionation, Fast Q anion exchange, and phenyl agarose chromatography. Gel chromatography and SDS-polyacrylamide electrophoresis experiments showed that the enzyme is a tetramer with subunit MW of 29 kDa. Among available second substrates, pyrophosphate showed the highest activity. Optimum temperature and pH were 45 degrees C and 5.5, respectively. The enzyme was chemically modified only by diethylpyrocarbonate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC), indicating that histidine and carboxylate are in the active site. pH studies showed that two histidines are involved in the binding of the substrates and a carboxylate in catalysis. Therefore, the chemical mechanism of the enzyme is likely that two histidines bind to pyrophosphate and carboxylate, respectively, and a carboxylate acts as a general base. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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