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The domain activities of the retroviral HIV-1 and simian immunodeficiency virus proteases were determined and described. The structure of the most 'open' conformation studied and unliganded HIV structures were then compared with their respective liganded structures in terms of the variations in the distance matrixes. The results revealed five domains of the protease dimer that rigidly move relative to each other. Thus, mutations at interdomain interfaces that support the unliganded form of the target active site was demonstrated to increase the off-rate of the inhibitor.

A model illustrating how the orientation of hydrophobic viral fusion peptides influence membrane fusion in lipids is presented. This model was applied in the study of the interaction of two peptides, which resemble the structure of the simian immunodeficiency virus (SIV) glycoprotein gp32, with model membranes. Results of X-ray diffraction experiments showed that viral fusion peptides function by destabilizing the lipid bilayers. These destabilizing effects influence the fusogenic action and fusion inhibitor action of the two SIV peptides.

A recombinant model for the ectodomain of the simian immunodeficiency virus (SIV) envelope protein gp41 is produced in Eschericia coli. A small, trimeric subdomain has been identified by proteolytic digestion of this gp41 fragment. The results showed that the subdomain is formed by two peptide fragments, spanning residues of 28-80 and residues 107-149 of SIV gp41. A proposed structure for the complex consists of a parallel, trimeric coiled-coil of the N-terminal peptide, surrounded by three C-terminal peptide helices in an antiparallel positions.

Crystallization of a type of simian immunodeficiency virus protease (SIV PR) which was covalently attached to the restrictor 1,2-epoxy-3 (p-nitrophenoxy) propane was characterized by X-ray crystallography. The starting template for the model of irreversible inhibitors of the SIV and associated human immunodeficiency virus (HIV-1) and HIV-2 PRs which are based on nonpeptide was shown by this structure.

Immunogenic peptides of the dominant antigenic region in the transmembrane protein of simian immunodeficiency virus (SIV) possess preferences for water solution conformations other than the extended chain form configuration typical of random coil peptides. This was indicated by conformational studies using nuclear magnetic resonance on two synthetic peptides which correspond to the N- and C- terminal halves of the SIV of macaque origin.

Atomic force microscopy (AFM) was used to determine whether negatively curved lipids influence the interaction of the simian immunodeficiency virus (SIV) fusion peptide with model membranes. Mixed DOPC/DPCC bilayers were used to probe the sensitivity of the SIV peptide toward curved lipids and it was found that a significant reduction in the bilayer thickness of DPCC domains occurs after short incubation times with the peptide, while after longer times, the domains evolve toward a thicker phase.