| Pak. J. Bot., 37(2): 299-306, 2005. | Back to Contents | ||||
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Updated: 09-07-09 | ||||
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PURIFICATION AND CHARACTERIZATION OF DIHYDROPYRIMIDINASE FROM ALBIZZIA
JULIBRISSIN
Abstract:
Dihydropyrimidinase (DHPase) was purified 74-fold over the initial Albizzia
extract using heat treatment, ammonium sulphate precipitation and sephadex
G-200 column chromatography. Its molecular mass, determined by SDS-PAGE,
was approximately 56 kDa. The optimum temperatures of DHPase were 60oC
and 55oC for dihydrouracil (DHU) and dihydrothymine (DHT), respectively.
Optimum pH value of DHPase for two substrates was found to be 9.5. The
stability of DHPase was determined both in crude enzyme extract and
in the sample obtained from ammonium sulphate precipitation. The effect
of some metal ions on this enzyme was also examined. Km values of the
enzyme for DHU and DHT were 0.33 mM and 0.37 mM, respectively. Vmax
values were found as 0.15 U/mL min-1 and 0.092 U/mL min-1 for DHU and
DHT, respectively. Department of Biology, Faculty of Science and Art, Balikesir University, Balikesir-10100, Turkey. |
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