This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wu, J. Z.
Right arrow Articles by Hong, Z.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wu, J. Z.
Right arrow Articles by Hong, Z.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, June 2005, p. 2164-2171, Vol. 49, No. 6
0066-4804/05/$08.00+0     doi:10.1128/AAC.49.6.2164-2171.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Phosphorylation of Ribavirin and Viramidine by Adenosine Kinase and Cytosolic 5'-Nucleotidase II: Implications for Ribavirin Metabolism in Erythrocytes{dagger}

Jim Zhen Wu,* Gary Larson, Heli Walker, Jae Hoon Shim, and Zhi Hong

Drug Discovery, Valeant Pharmaceuticals International, 3300 Hyland Avenue, Costa Mesa, California 92626

Received 10 November 2004/ Returned for modification 28 January 2005/ Accepted 11 February 2005

Many nucleoside analog drugs, such as ribavirin and viramidine, are activated or metabolized in vivo through 5'-phosphorylation. In this report, we determined the steady-state kinetic parameters for 5'-monophosphorylation of ribavirin and viramidine by adenosine kinase. The apparent Km for ribavirin is 540 µM, and kcat is 1.8 min–1. Its catalytic efficiency of 3.3 x 10–3 min–1 · µM–1 is 1,200-fold lower than that of adenosine. In contrast to the common belief that ribavirin is exclusively phosphorylated by adenosine kinase, cytosolic 5'-nucleotidase II was found to catalyze ribavirin phosphorylation in vitro. The reaction is optimally stimulated by the physiological concentration of ATP or 2,3-bisphosphoglycerate. In phosphate-buffered saline plus ATP and 2,3-bisphosphoglycerate, the apparent Km for ribavirin is 88 µM, and kcat is 4.0 min–1. These findings suggest that cytosolic 5'-nucleotidase II may be involved in ribavirin phosphorylation in vivo. Like ribavirin, viramidine was found to be phosphorylated by either adenosine kinase or cytosolic 5'-nucleotidase II, albeit with a much lower activity. The catalytic efficiency for viramidine phosphorylation is 10- to 330-fold lower than that of ribavirin, suggesting that other nucleoside kinase(s) may be involved in viramidine phosphorylation in vivo. Both ribavirin and viramidine are not phosphorylated by deoxycytidine kinase and uridine-cytidine kinase. The coincidence of presence of high concentrated 2,3-bisphosphoglycerate in erythrocytes suggests that cytosolic 5'-nucleotidase II could play an important role in phosphorylating ribavirin and contribute to anabolism of ribavirin triphosphate in erythrocytes. Elucidation of ribavirin and viramidine phosphorylation mechanism should shed light on their in vivo metabolism, especially the ribavirin-induced hemolytic anemia in erythrocytes.

* Corresponding author. Mailing address: Drug Discovery, Valeant Pharmaceuticals International, 3300 Hyland Avenue, Costa Mesa, CA 92626. Phone: (714) 545-0100, ext. 3024. Fax: (714) 668-3142. E-mail: jwu{at}valeant.com.

{dagger} The paper is dedicated to Christopher Walsh on the occasion of his 60th birthday.

Antimicrobial Agents and Chemotherapy, June 2005, p. 2164-2171, Vol. 49, No. 6
0066-4804/05/$08.00+0     doi:10.1128/AAC.49.6.2164-2171.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Endres, C. J., Moss, A. M., Ke, B., Govindarajan, R., Choi, D.-S., Messing, R. O., Unadkat, J. D. (2009). The Role of the Equilibrative Nucleoside Transporter 1 (ENT1) in Transport and Metabolism of Ribavirin by Human and Wild-Type or Ent1(-/-) Mouse Erythrocytes. J. Pharmacol. Exp. Ther. 329: 387-398 [Abstract] [Full Text]  
  • Mira, J. A., Lopez-Cortes, L. F., Barreiro, P., Tural, C., Torres-Tortosa, M., de los Santos Gil, I., Martin-Rico, P., Rios-Villegas, M. J., Hernandez-Burruezo, J. J., Merino, D., Lopez-Ruz, M. A., Rivero, A., Munoz, L., Gonzalez-Serrano, M., Collado, A., Macias, J., Viciana, P., Soriano, V., Pineda, J. A. (2008). Efficacy of pegylated interferon plus ribavirin treatment in HIV/hepatitis C virus co-infected patients receiving abacavir plus lamivudine or tenofovir plus either lamivudine or emtricitabine as nucleoside analogue backbone. J Antimicrob Chemother 62: 1365-1373 [Abstract] [Full Text]  
  • Chevaliez, S., Brillet, R., Lazaro, E., Hezode, C., Pawlotsky, J.-M. (2007). Analysis of Ribavirin Mutagenicity in Human Hepatitis C Virus Infection. J. Virol. 81: 7732-7741 [Abstract] [Full Text]  
  • Wallden, K., Stenmark, P., Nyman, T., Flodin, S., Graslund, S., Loppnau, P., Bianchi, V., Nordlund, P. (2007). Crystal Structure of Human Cytosolic 5'-Nucleotidase II: INSIGHTS INTO ALLOSTERIC REGULATION AND SUBSTRATE RECOGNITION. J. Biol. Chem. 282: 17828-17836 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»