Yeasts 5 -nucleotidase

Nucleotidase (5 -ribonucleotide phosphohydrolase, EC 3.1.3.5) is widely distributed in nature and a voluminous literature has appeared in the past decade on the enzyme from vertebrate tissues, seminal fluid, snake venoms, yeasts, and bacteria. Studies regarding the discovery and early investigations of the enzyme have been reviewed by Heppel (1) and... 

Murguia, J.R., Belles, J.M., and Serrano, R., 1996, The yeast Hal2 nucleotidase is an in vivo target of salt toxicity. J Biol. Chem. 271 29029-29033. 

Quintero, F.J., Garciadeblas, B., and Rodriguez-Navarro, A., 1996, The Sail gene of Arabidopsis, encoding an enzyme with 3,(2,),5,(-bisphosphate nucleotidase and inositol polyphosphatase 1-phosphatase activities, increases salt tolerance in yeast. Plant Cell 8 529-537. 

Phosphodiesterases, phosphatases, 5 -nucleotidases, 3 -nucleotidases and phosphotransferases have been discussed in the section on purine breakdown. Some of these enzymes also act on pyrimidine nucleotides, yielding either the nucleoside or the free base. Cytosine deaminases have been found in yeast and E. coli. Cyti-dine and cytidylic acid deaminases are present in extract of most mammalian tissue. The properties of these enzymes are still poorly understood. 

This compound has been isolated after subjecting yeast ribonucleic acid to brief acid hydrolysis. When it is treated with alkali there is cleavage at (1), with the formation and subsequent hydrolysis of a cyclic anhydride of guanylic acid. The final products are guanosine-2 -phosphate, guanosine-3 -phosphate, and cytidine-3 -phosphate. The last two would be split by 3-nucleotidase from barley. 

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