Adenosine-5´-Tetraphosphate and Guanosine-5´-Tetraphosphate: New Substrates of the Cytosolic Exopolyphosphatase of the Yeast Saccharomyces cerevisiae

T. V. Kulakovskaya,^1,2 N. A. Andreeva,¹ and I. S. Kulaev¹

¹Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 923-3602.

²To whom correspondence should be addressed.

Submitted May 5, 1997; revision submitted June 4, 1997.

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A cytosolic preparation of Saccharomyces cerevisiae is capable of hydrolyzing adenosine-5´-tetraphosphate and guanosine-5´-tetraphosphate with activities which are 1.5-2 times greater than that with polyP₁₅. The apparent K_m values for hydrolysis of adenosine-5´-tetraphosphate and guanosine-5´-tetraphosphate are 100 and 80 µM, respectively. A comparative study of inhibitors shows that these activities are inherent characteristics of these exopolyphosphatases.

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KEY WORDS: adenosine-5´-tetraphosphate, guanosine-5´-tetraphosphate, polyphosphates, exopolyphosphatase, cytosol, yeast.

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