Gas-Phase Studies of Hypoxanthine-Guanine-(Xanthine) Phosphoribosyltransferase (HG(X)PRT) Substrates

Zhang, Lanxin; Kiruba, G. S. M.; Lee, Jeehiun K.

doi:10.1021/acs.joc.3c00115

Cited by 1 publication

(2 citation statements)

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“…The second residue that could potentially have suboptimal interactions with the T-705 moiety, as opposed to the natural purine, is Asp106. Various studies suggest that hypoxanthine/guanine as free nucleobases form hydrogen bonds with residues homologous to Asp106 through the protonated nitrogen-7 atom, and this interaction is believed to play a role in the natural purine deprotonation. ,− In contrast, the nucleophilic oxygen atoms of T-705 moiety are exposed to the negatively charged Asp106 side chain in Tth HGPRT/Asp137 in Hsa HGPRT (Figure B,D). Thus, the orientation of negatively charged atoms toward each other could hypothetically constitute a suboptimal enzyme-ligand interaction, suggesting Asp106 as another potential design hot spot.…”

Section: Resultsmentioning

confidence: 99%

“…Another curious feature of the HGPRT mechanism worthy of discussion is the role of Asp106 in nucleobase deprotonation. Studies on HGPRT from other sources suggest that residues homologous to Asp106 in Tth HGPRT can play a role in the deprotonation of the purine nucleobases. ,− In contrast to the natural reaction, substitutions of Asp106 to other residues had a significant positive effect on T-705/T-1105 phosphoribosylation; therefore, the mentioned acidic residue may not be important for the deprotonation of these unnatural nucleobases.…”

Section: Discussionmentioning

confidence: 99%

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Designing an Efficient Biocatalyst for the Phosphoribosylation of Antiviral Pyrazine-2-carboxamide Derivatives

Zayats,

Fateev,

Abramchik

et al. 2024

ACS Catal.

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The development of technologies for the efficient synthesis of innovative antiviral compounds remains an important challenge for modern biotechnology, especially in the context of the recent COVID-19 pandemic. One of the drugs that is currently in the research spotlight for potential anti-SARS-CoV-2 activity is the purine mimetic prodrug compound T-705, also known as favipiravir. Along with a similar compound, T-1105, the activation of T-705 is limited by the low rate of phosphoribosylation, mediated by an enzyme named hypoxanthineguanine phosphoribosyltransferase (HGPRT). Therefore, the synthesis of phosphoribosylated/ribosylated derivatives of these prodrugs is a viable direction for the discovery and development of antiviral pharmaceuticals. However, the chemical synthesis of such compounds is a complex and laborious process, whereas enzymatic cascades are not feasible because of the narrow HGPRT substrate specificity. Here, we report the successful rational design of an efficient biocatalyst for T-705/T-1105 phosphoribosylation. With two rounds of Thermus thermophilus HB27 HGPRT active site optimization, we have achieved a 325-fold increase in k cat toward the compound T-705 and a 125-fold increase toward T-1105 accompanied by a multifold decrease in K M . The practical applicability of the designed mutant was illustrated through the preparative synthesis of T-705/T-1105 nucleotide derivatives. Our engineered biocatalyst can become a basis for the technologies of enzymatic and chemoenzymatic synthesis of various T-705/T-1105 derivatives with proven antiviral activity. Moreover, our results provide insight into the molecular mechanism of T-705/T-1105 phosphoribosylation, including the experimental evidence explaining the reasons behind the low activity of HGPRT toward these compounds.

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