Sandbox 50: Difference between revisions

Because lipase is a member of the serine esterase family, it can be inhibited by serine reagents. In an effort to further characterize the mechanism and active site binding of a substrate, a C11 alkyl phosphonate (C11P) compound was synthesized and found to be an inhibitor of lipase. In this study, human pancreatic lipase was purified and porcin-activated colipase was used to activate it. The horse pancreatic lipase and human pancreatic lipase enzymes are highly conserved, so active site resides are similar.<ref>http://www.rcsb.org/pdb/explore/explore.do?structureId=1LPB</ref> The <scene name='Sandbox_50/C11_alkyl_phosphonate_in_activ/1'>crystal structure</scene> of this molecule inhibiting the activated lipase-colipase complex was determined at 2.46 A (Lipase B chain in green, colipase in blue, C11 alkyl phosphonate in red). C11P was found covalently bound at the <scene name='Sandbox_50/C11p_bound/1'>active site</scene> Ser 152 (red), and phe 77 (purple) and Leu 153 (green) amides formed hydrogen bonds with the oxygen of the phosphorus ester of C11P. This confirms mechanism speculations of the role of these residues in oxyanion stabilization. The geometry of this oxyanion hole was conserved when two other inhibitors were characterized in the active site.<ref>http://pubs.acs.org/doi/abs/10.1021/bi00009a003</ref> C11P was shown to be <scene name='Sandbox_50/C11p_bound_h_phobics/1'>further stabilized</scene> by van der Waals contacts with hydrophobic side chains Ala178,Phe215, Prol80, Tyrll4, Leu213 (shown in blue)