Sandbox Reserved 955: Difference between revisions

HIV-1 protease is a dimer  of identical polypeptide chains : it's composed of  two symmetrically related subunits, each consisting of 99 amino acid residues. Its structure is composed of A,B chains,<scene name='60/604474/Helix/1'>two helix</scene> (one in each subunit)and <scene name='60/604474/Sheets/2'>bêta sheets</scene>.The subunits come together in such as way as to form a tunnel where they meet and in the inside of which  is located the active site of the protease. The active site consists of two <scene name='60/604474/Catalytic/5'>Asp-Thr-Gly</scene> conserved sequences, making it a member of the aspartyl protease family. The two Asp's are essential catalytic residues either interact with the incoming water or protonate the carbonyl to make the carbon more electrophilic for the incoming water. The two flexible flaps on the top of the tunnel  move to allow proteins to enter the tunnel. The flaps undergo a dramatic movement, shifting from an open to a closed conformation to bind the target in an appropriate conformation for cleavage. <ref>http://proteopedia.org/wiki/index.php/HIV-1_protease</ref>