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netLibrary - eBook Summary Structure-based Drug Design by ...

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Document<br />

Page 53<br />

NRTIs in light of available structural data might provide information that could be used in the<br />

development of improved NRTIs that are more effective against the commonly observed NRTI-resistant<br />

HIV-1 variants. A viable drug-resistant RT mutant should be able to recognize and incorporate normal<br />

nucleoside triphosphate, yet reject a nucleoside analog. The only difference between normal nucleotide<br />

substrates and the NRTIs is the modification of the sugar moiety. This alteration may affect sugar<br />

puckering and the conformation of the glycosyl bond. Recognition of these differences could render the<br />

triphosphate form of the nucleoside analog a good substrate for wild-type RT but a poor substrate for a<br />

drug-resistant variant of RT.<br />

Structural analysis of HIV-1 RT has shown that most of the NRTI-resistance mutations are not located<br />

close to the putative dNTP-binding site and are unlikely to have a direct impact on the binding of dNTP<br />

analogs (Figure 5 and<br />

Figure 5<br />

A close-up view showing the relative locations of the commonly identified<br />

drug-resistance mutations for NRTIs (in dark-gray) and for NNRTIs (in light-gray) with<br />

respect to the bound DNA. Most of the NRTI-resistance mutations are not located at the<br />

putative dNTP-binding site, but are at positions to have potential interactions with the<br />

nucleic acid template-primer. Conversely, all the NNRTI-resistance mutations are<br />

clustered around the NNIBP and have direct contacts with NNRTIs or have direct effect on<br />

inhibitor binding.<br />

http://legacy.netlibrary.com/nlreader/nlReader.dll?bookid=12640&filename=Page_53.html (1 of 2) [4/5/2004 4:49:46 PM]

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