Lipase: Difference between revisions
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==Introduction== | ==Introduction== | ||
Lipase is a hydrolase that catalyzes the breakdown of lipids by hydrolyzing the esters of fatty acids. Lipases are important in digestion, promoting absorption of fats in the intestines. Lipase is primarily found in the pancreas but is also found in the mouth and the stomach. Pancreatic lipase (PDB ID: 1HPL) which is pictured below is a carboxylic ester hydrolase. It is also commonly called pancreatic triacylglycerol lipase and its enzyme class number is E.C. 3.1.1.3 <ref name="1HPL PDB SUM">[http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1hpl&template=main.html] 1HPL PDB SUM </ref>. The reaction catalyzed by this enzyme is shown below. [[Image:Picture 1.png]] | Lipase is a hydrolase that catalyzes the breakdown of lipids by hydrolyzing the esters of fatty acids. Lipases are important in digestion, promoting absorption of fats in the intestines. Lipase is primarily found in the pancreas but is also found in the mouth and the stomach. Pancreatic lipase (PDB ID: 1HPL) which is pictured below is a carboxylic ester hydrolase. It is also commonly called pancreatic triacylglycerol lipase and its enzyme class number is E.C. 3.1.1.3 <ref name="1HPL PDB SUM">[http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1hpl&template=main.html] 1HPL PDB SUM </ref>. The reaction catalyzed by this enzyme is shown below. | ||
[[Image:Picture 1.png]] | |||
Further breakdown ultimately results in 2-monoacylglycerols and free fatty acids <ref name= "A cross-linked complex between horse pancreatic lipase and colipase">[http://www.sciencedirect.com/science/article/pii/0014579389815923] A cross-linked complex between horse pancreatic lipase and colipase</ref>. Pancreatic liapase is a 50 kDa protein, consisting of two identical, 449 residue chains <ref name= "1HPL PDB">[http://www.pdb.org/pdb/explore/explore.do?structureId=1HPL] 1HPL PDB</ref>. The determination of the structure and function of lipase was a gradual process. Lipase activity was first demonstrated in the pancreas by Claude Bernard in 1846. It wasn't until 1955 that Mattson and Beck demonstrated a high-specificity of pancreatic lipase for triglyceride primary esters <ref name= "History of Lipids">[http://www.cyberlipid.org/history/history1.htm] History of Lipids</ref>. In recent years, determination of the crystal structure of pancreatic lipase has become the focus and many scientists have worked to further this. See also [[Molecular Playground/Pancreatic Lipase]]. | Further breakdown ultimately results in 2-monoacylglycerols and free fatty acids <ref name= "A cross-linked complex between horse pancreatic lipase and colipase">[http://www.sciencedirect.com/science/article/pii/0014579389815923] A cross-linked complex between horse pancreatic lipase and colipase</ref>. Pancreatic liapase is a 50 kDa protein, consisting of two identical, 449 residue chains <ref name= "1HPL PDB">[http://www.pdb.org/pdb/explore/explore.do?structureId=1HPL] 1HPL PDB</ref>. The determination of the structure and function of lipase was a gradual process. Lipase activity was first demonstrated in the pancreas by Claude Bernard in 1846. It wasn't until 1955 that Mattson and Beck demonstrated a high-specificity of pancreatic lipase for triglyceride primary esters <ref name= "History of Lipids">[http://www.cyberlipid.org/history/history1.htm] History of Lipids</ref>. In recent years, determination of the crystal structure of pancreatic lipase has become the focus and many scientists have worked to further this. See also [[Molecular Playground/Pancreatic Lipase]]. | ||
==Structure== | ==Structure== | ||
The <scene name='Lipase/Secondary_structures/1'>secondary structure</scene>s of lipase (just one subunit) include 102 residues which create 13 alpha helices, shown in red, and 139 residues involved in beta sheets totaling 28 strands, shown in gold. The alpha helices account fot 22% of the proteing, while the beta sheets comprise 30%. | The <scene name='Lipase/Secondary_structures/1'>secondary structure</scene>s of lipase (just one subunit) include 102 residues which create 13 alpha helices, shown in red, and 139 residues involved in beta sheets totaling 28 strands, shown in gold. The alpha helices account fot 22% of the proteing, while the beta sheets comprise 30%. Each chain contains two well defined <scene name='Lipase/N_and_c_terminus/1'>domains</scene>. The N terminal domain, shown in blue, is characterized by an alpha/beta hydrolase fold. While the C terminal domain, shown in green, contains a beta sheet sandwich which interacts with colipase <ref>http://www.pdb.org/pdb/explore/explore.do?structureId=1HPL</ref>. Each monomer and dimer strucutre of li[ase is held together by disulfide bonds, hydrogen bonds, and electrostatic interactions (salt bridges). Lipase has 12 total <scene name='Lipase/Disulfide_bonds/2'>disulfide bonds</scene> between Cys residues. <scene name='Lipase/Salt_bridges/1'>Salt bridges</scene> are formed between the positively charge nitrogens (blue) in Arg and Lys, and negative oxygens (red) in Asp and Glu residues. <scene name='Lipase/Hydrogen_bonds/1'>Hydrogen bonds</scene> also stabilize the enzyme <scene name='Lipase/Main_chain_h_bonds/1'>between main chain atoms</scene> and <scene name='Lipase/Side_chain_h_bonds/1'>between side chain atoms</scene>. Lipase has a distinct distribution of hydrophobic and hydrophilic residues. Hydrophobic collapse contributes to much of the secondary and teritary structures, as the <scene name='Lipase/Hphobic_residues/2'>TextToBeDisplayed</scene>, shown in grey, point twoards the interior of the protein. Coversely, the <scene name='Lipase/Polar_residues/1'>polar residues</scene>, in pink, point outwards <ref>http://www.pdb.org/pdb/explore/remediatedSequence.do?structureId=1HPL</ref>. | ||
<scene name='Lipase/Main_chain_h_bonds/1'> | |||
<scene name='Lipase/Side_chain_h_bonds/1'> | |||
==Hydrophobicity/Hydrophillicity== | ==Hydrophobicity/Hydrophillicity== | ||
