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Puromycin-sensitive aminopeptidase: an antiviral prodrug activating enzyme

Ulrika Tehler1, Cara H Nelson, Larryn W Peterson

  • 1Department of Pharmaceutical Sciences and Center for Molecular Drug Targeting, College of Pharmacy, The University of Michigan, 428 Church St., Ann Arbor, MI 48109-1065, United States.

Antiviral Research
|December 9, 2009
PubMed

Insights

Puromycin-sensitive aminopeptidase activates the promising antiviral prodrug Val-Ser-cyclic HPMPC (Val-Ser-cHPMPC), enhancing oral bioavailability. This enzyme is a key target for developing improved antiviral therapies against orthopox viruses.

Area of Science:

  • Biochemistry
  • Pharmacology
  • Virology

Background:

  • Cidofovir (HPMPC) is a broad-spectrum antiviral with potential against orthopox viruses, but limited by poor oral bioavailability.
  • Val-Ser-cyclic HPMPC (Val-Ser-cHPMPC) is a peptide prodrug designed to improve cidofovir's permeability and bioavailability.
  • Puromycin-sensitive aminopeptidase has been identified as a key enzyme in activating this prodrug.

Purpose of the Study:

  • To identify and characterize the enzyme responsible for activating the cidofovir prodrug, Val-Ser-cHPMPC.
  • To investigate the substrate specificity of puromycin-sensitive aminopeptidase for Val-Ser-cHPMPC.
  • To evaluate the role of puromycin-sensitive aminopeptidase in the in vivo activation of Val-Ser-cHPMPC.

Main Methods:

  • Partial purification and characterization of puromycin-sensitive aminopeptidase from Caco-2 cell homogenates.
  • Generation and kinetic analysis of recombinant puromycin-sensitive aminopeptidase.
  • Investigation of substrate specificity using various amino acid substrates and the prodrug Val-Ser-cHPMPC.

Main Results:

  • Puromycin-sensitive aminopeptidase was identified as the enzyme that removes the l-Valine residue from Val-Ser-cHPMPC, initiating prodrug activation.
  • The enzyme demonstrated substrate specificity, with preferences for certain amino acids and higher activity towards the prodrug compared to a model substrate.
  • Enzymatic hydrolysis by puromycin-sensitive aminopeptidase, followed by chemical hydrolysis, generates the active cidofovir (cHPMPC).

Conclusions:

  • Puromycin-sensitive aminopeptidase plays a crucial role in the in vivo activation of the promising antiviral prodrug Val-Ser-cHPMPC.
  • The enzyme's activity and substrate specificity suggest it is a viable target for designing future prodrugs with enhanced bioavailability.
  • Targeting puromycin-sensitive aminopeptidase could lead to more effective oral antiviral therapies, particularly for orthopox virus infections.

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