PMID: 4364532Apr 1, 1974

Regulation of a plant 5'(3')-ribonucleotide phosphohydrolase by cyclic nucleotides and pyrimidine, purine, and cytokinin ribosides

Proceedings of the National Academy of Sciences of the United States of America
G M Polya


A highly specific 5'(3')-ribonucleotide phosphohydrolase has been purified extensively from wheat seedling leaves. While catalyzing the hydrolysis of a wide variety of phosphomonoesters, the enzyme has K(m) values for adenosine 5'-monophosphate and adenosine 3'-monophosphate in the micromolar range and appears highly specific for 5'- and 3'-ribonucleoside monophosphates as substrates at pH 5.0. The cyclic nucleotides adenosine 3':5'-cyclic monophosphate, guanosine 3':5'-cyclic monophosphate, and 8-bromoadenosine 3':5'-cyclic monophosphate, as well as 8-bromoadenosine 5'-monophosphate, are powerful competitive inhibitors of the enzyme; the apparent K(i) values for these nucleotides are 3.4 muM, 1.6 muM, 26 muM, and 9.1 muM, respectively. The enzyme is inhibited noncompetitively by a variety of pyrimidine and purine (including cytokinin) ribosides and 2'-deoxyribosides. Since the cyclic nucleotide competitive inhibitors are also active growth promoters of higher plants, and, furthermore, since elevation of cyclic AMP levels appears to be a consequence of some phytohormone treatments that promote plant growth, it is suggested that negative control of this 5'(3')-ribonucleotide phosphohydrolase may be a significant component of gro...Continue Reading


Oct 3, 1977·Advances in Enzyme Regulation·P Fritzson
Sep 23, 1992·Biochimica Et Biophysica Acta·G M Polya, R E Wettenhall
Jun 1, 1997·Plant Physiology·A R PenheiterG Sarath
May 28, 2013·Langmuir : the ACS Journal of Surfaces and Colloids·Min Wook LeeSam S Yoon


Apr 2, 1971·Biochemical and Biophysical Research Communications·S Azhar, C R Murti
Aug 1, 1971·Life Sciences. Pt. 2: Biochemistry, General and Molecular Biology·D Salomon, J P Mascarenhas
Feb 1, 1972·Proceedings of the National Academy of Sciences of the United States of America·H N WoodA C Braun
Apr 14, 1972·Biochemical and Biophysical Research Communications·D Salomon, J P Mascarenhas
Apr 14, 1972·Biochemical and Biophysical Research Communications·M ShimoyamaI Ueda
Jan 30, 1973·Biochemistry·R A FelicioliP L Ipata
Feb 1, 1969·Chemical & Pharmaceutical Bulletin·M Ikehara, S Uesugi

Related Concepts

Cyclic AMP, (R)-Isomer
5'-Adenylic Acid
Cyclic GMP
Allosteric Regulation

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