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• pKa of the side chain R-groups: D (3.9), E (4.2), H (6.0)' C (8.3), Y (10.1), K (10.5), and R (12.5). •pka of amino acids a-amino group (9.6) and a-carboxyl group (2.1). • pKa of N-terminal oligopeptide a-amino group (7.4) and C-terminal a-carboxyl group (3.6).
3. what are the amino acid functional groups that can act as general acids/general bases? 4. HIV-protease performs post-transcriptional cleavage of new HIV polypeptides for the budding to exit the host cells in life cycle continuation. a) Catalysis of protein chain cleavage by this protease is mediated by twin Asp-25 residues juxtaposed in the active site. These two aspartates are said to form a 'catalytic dyad'. One of these carboxyl groups exhibits an unusually low pKa of 3.3 and the other displays an unusually high pKa of 5.3. b) describe how the dyad may involve the low-barrier hydrogen bonds to perform its function. c) Crixivan is an HIV-1 inhibitor targeting HIV protease. Why Crixivan does not target normal human protein?