Inhibitor stabilization of human immunodeficiency virus type-2 proteinase dimer formation.
We report the first direct observation of the subunit self-association behavior of highly purified recombinant human immunodeficiency virus type-2 (HIV-2) proteinase. Multiple samples of enzyme were subjected to sedimentation equilibrium analytical ultracentrifugation sequentially at 8.8 degrees C and two pH values in the presence and absence of a C2 symmetric, peptidomimetic inhibitor. At both pH values the enzyme exhibited sedimentation equilibrium behavior which fit a monomer-dimer-tetramer model. In the absence of inhibitor, the apparent Kd for dimer formation was less than approximately 100 microM and the apparent Kd for the weaker dimer-tetramer association was greater than approximately 100 microM. In the presence of inhibitor, at either pH, dimer formation was more strongly favored as indicated by a approximately 5-14-fold decrease in the apparent Kd for dimer formation and a approximately 1.2-4-fold increase in the apparent Kd for tetramer formation. The enhanced formation of dimer and decrease in higher order self-associated forms in the presence of an inhibitor is consistent with inhibitor stabilization of an active dimer. The inhibitor-induced stabilization of the dimeric species is consistent with a model for substrate-induced formation of active proteinase dimers in virion assembly.
Protein Biochemistry Research, Abbott Laboratories, Abbott Park, Illinois 60064.
T F
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Holzman
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Kohlbrenner
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Weigl
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J
Rittenhouse
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Kempf
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Erickson
D017320:HIV Protease Inhibitors; D015498:HIV-2 / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D011725:Pyridines / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014461:Ultracentrifugation
D017320:HIV Protease Inhibitors; D011725:Pyridines; C071232:A 76889