Substrate analogue inhibition and active site titration of purified recombinant HIV-1 protease.

Published

Journal Article

The aspartyl protease of human immunodeficiency virus 1 (HIV-1) has been expressed in Escherichia coli at high levels, resulting in the formation of inclusion bodies which contain denatured insoluble aggregates of the protease. After solubilization of these inclusion bodies in guanidinium chloride, the protease was purified to apparent homogeneity by a single-step reverse-phase HPLC procedure. The purified, but inactive, protein was denatured in 8 M urea and refolded to produce the active protease. Enzyme activity was demonstrated against the substrate H-Val-Ser-Gln-Asn-Tyr-Pro-Ile-Val-OH, modeled after the cleavage region between residues 128 and 135 in the HIV gag polyprotein. With this substrate, a Vmax of 1.3 +/- 0.2 mumol/(min.mg) and KM of 2.0 +/- 0.3 mM were determined at pH 5.5. Pepstatin (Iva-Val-Val-Sta-Ala-Sta-OH) and substrate analogues with the Tyr-Pro residues substituted by Sta, by Phe psi [CH2N]Pro, and by Leu psi [CH(OH)CH2]Val inhibited the protease with KI values of 360 nM, 3690 nM, 3520 nM, and less than 10 nM, respectively. All were competitive inhibitors, and the tightest binding compound provided an active site titrant for the quantitative determination of enzymatically active HIV-1 protease.

Full Text

Cited Authors

  • Tomasselli, AG; Olsen, MK; Hui, JO; Staples, DJ; Sawyer, TK; Heinrikson, RL; Tomich, CS

Published Date

  • January 1990

Published In

Volume / Issue

  • 29 / 1

Start / End Page

  • 264 - 269

PubMed ID

  • 2182116

Pubmed Central ID

  • 2182116

Electronic International Standard Serial Number (EISSN)

  • 1520-4995

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00453a036

Language

  • eng