The Journal of Biochemistry
Online ISSN : 1756-2651
Print ISSN : 0021-924X
An Ecto-Enzyme from Sulfolobus acidocaldarius Strain 7 Which Catalyzes Hydrolysis of Inorganic Pyrophosphate, ATP, and ADP: Purification and Characterization
Toyoki AmanoTakayoushi WakagiTairo Oshima
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JOURNAL FREE ACCESS

1993 Volume 114 Issue 3 Pages 329-333

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Abstract

Membranes of Sulfolobus acidocaldarius, a thermoacidophilic archaebacterium, show novel enzymatic activities to hydrolyze PPi, ATP, and ADP at an optimal pH of 3, equal to the growth optimum. The activity increased by about 2-fold on addition of PPi and/or P1 to the growth medium, when yeast extract and casamino acids were removed. The enzyme which hydrolyzes PPi at pH 3 was solubilized and purified by successive chromatogra-phies. The final preparation showed a 26 kDa single band on SDS-PAGE, and a molecular mass of 35 kDa on gel permeation chromatography. The Km and Vmax for PPi were 0.16mM and 33μmol Pi released/min/mg at 55°C. ATP and ADP were also good substrates. Divalent cations were not essential for activity. Substrate inhibition at more than 5mM PPi, ATP or ADP was observed. AMP, glucose-6-phosphate, and p-nitrophenyl phosphate were not hydrolyzed at all. The activity was 4-fold stimulated by addition of the lipid fraction extracted from the organism.

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© The Japanese Biochemical Society
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