Mechanism of action of aspartic proteases. III. Conformational characteristics of HIV-1 protease inhibitor JG-365] |
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Authors: | M E Popov I V Kashparov L D Rumsh E M Popov |
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Institution: | Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia. popov@enzyme.siobc.ras.ru |
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Abstract: | A set of conformations was shown to be characteristic of the free-state spatial structure of substrate-like inhibitor JG-365 for aspartic protease from HIV-1. Among them, the lowest-energy conformations have a folded form of the peptide backbone. The inhibitor has a noncleavable hydroxyethylamine group with an additional chiral center in its structure. Our calculations showed that only the S-isomer of the inhibitor displays conformational characteristics that practically coincide with those of the native substrate for HIV-1 protease. One of the calculated conformations with a completely extended main chain and a relative energy of 9.5 kcal/mol very closely mimics the experimentally observed structure of the inhibitor in the enzyme-inhibitor complex. The realization of this structure is unlikely for a free inhibitor, because it has only a small number of interresidual noncovalent interactions in the extended conformation; these are presumably compensated for by intermolecular interactions at the active site of the enzyme. |
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