 human immunodeficiency virus type 1 protease is inhibited in vitro by zinc ions at neutral ph . 
 the binding site of these ions is not known ; however , experimental data suggest that binding may occur in the active site . to examine the possibility of zinc binding in the active site , molecular dynamics simulations in the presence and absence of zinc 
 have been carried out to 200 psec . 
 the results are compared with the 2.8-a crystallographic structures of a synthetic hiv-1 protease , and a zinc binding site at the catalytic aspartate residues ( asp-25 , asp-25 ' ) is proposed . 
 molecular dynamics simulations show that the zinc ion remains stably bound in this region , coordinating the carboxylate side chains of both aspartate residues . 
 interaction with zinc does not disrupt the dimeric structure of the protein or significantly alter the structure of the active site . 
 these data are consistent with experimental studies of hiv-1 protease inhibition by zinc and give strong evidence that this is the binding site that leads to inactivation.imagesp246-afigure 1.figure 2.figure 3 . 
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