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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 catalyzes the hydrolysis of triacylglycerols into 2-monoacylglycerols and free fatty acids. Pancreatic liapase consists of two identical | + | 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 catalyzes the hydrolysis of triacylglycerols into 2-monoacylglycerols and free fatty acids. Pancreatic liapase consists of two identical, 449 residue chains. |
<applet load='1HPL' size='400' frame='true' align='right' scene='Sandbox_45/Pancreatic_lipase/1' caption='Horse Pancreatic Lipase at 2.3 Angstroms Resolution (PDB ID: 1HPL)' /> | <applet load='1HPL' size='400' frame='true' align='right' scene='Sandbox_45/Pancreatic_lipase/1' caption='Horse Pancreatic Lipase at 2.3 Angstroms Resolution (PDB ID: 1HPL)' /> | ||
== Structure == | == Structure == | ||
| - | + | Pancreatic lipase has a <scene name='Sandbox_45/Secondary_structure/1'>secondary structure</scene> consisting of 22% alpha helices, which are shown in blue, and 30% beta sheets, which are shown in bright green. The rest of the secondary structure consists of ordered, nonrepetitive structure. Lipase contains two <scene name='Sandbox_45/Domains/1'>domains</scene> in each chain. The N-terminal domain (red) is 337 residues long and consists mainly of 3 layer (alpha, beta, alpha) sandwich. The C-terminal domain (yellow) is 112 residues long and consists primarily of beta sandwich. The N-terminal and C-terminal domains can be better visualized by a <scene name='Sandbox_45/Pancreatic_lipase/2'>rainbow ribbon diagram</scene>. In this representation, the N-terminal domain begins as blue and as it approaches the C-terminal domain, it changes color until it reaches red. Lipase also contains six <scene name='Sandbox_45/Disulfide_bonds/3'>disulfide bonds</scene>. Disulfide bonds are indicated by the yellow rods and the Cys residues that they connect are shown in white. These disulfide bonds occur between Cys 4 and Cys 10, Cys 90 and Cys 101, Cys 237 and Cys 261, Cys 285 and Cys 296, Cys 299 and Cys 304, and Cys 433 and Cys 449. Calcium ions, shown as bright green balls, are also seen interacting with the protein. | |
== Hydrophobicity/Hydrophilicity== | == Hydrophobicity/Hydrophilicity== | ||
Revision as of 18:32, 10 November 2011
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| Please do NOT make changes to this Sandbox. Sandboxes 30-60 are reserved for use by Biochemistry 410 & 412 at Messiah College taught by Dr. Hannah Tims during Fall 2012 and Spring 2013. |
Contents |
Lipase
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 catalyzes the hydrolysis of triacylglycerols into 2-monoacylglycerols and free fatty acids. Pancreatic liapase consists of two identical, 449 residue chains.
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Structure
Pancreatic lipase has a consisting of 22% alpha helices, which are shown in blue, and 30% beta sheets, which are shown in bright green. The rest of the secondary structure consists of ordered, nonrepetitive structure. Lipase contains two in each chain. The N-terminal domain (red) is 337 residues long and consists mainly of 3 layer (alpha, beta, alpha) sandwich. The C-terminal domain (yellow) is 112 residues long and consists primarily of beta sandwich. The N-terminal and C-terminal domains can be better visualized by a . In this representation, the N-terminal domain begins as blue and as it approaches the C-terminal domain, it changes color until it reaches red. Lipase also contains six . Disulfide bonds are indicated by the yellow rods and the Cys residues that they connect are shown in white. These disulfide bonds occur between Cys 4 and Cys 10, Cys 90 and Cys 101, Cys 237 and Cys 261, Cys 285 and Cys 296, Cys 299 and Cys 304, and Cys 433 and Cys 449. Calcium ions, shown as bright green balls, are also seen interacting with the protein.
Hydrophobicity/Hydrophilicity
In pancreatic lipase, there is a relatively equal distribution of . Hydrophobic residues are shown in red and hydrophillic residues in blue when clicking the green link. contribute to the relative hydophilicity of the protein since they can be protonated and deprotonated at varying pH levels, causing a charge to be present. The distribution and number of acidic (red) and basic (blue) residues is relatively even. White coloring represents nonpolar residues.
Catalytic Function
Pancreatic lipase contains three important that form the catalytic triad. They are highlighted in yellow. These three catalytic residues are all located in the N terminal domain and consist of Ser 152, Asp 172, and His 263. Serine functions to form a covalent bond to the ester, forming a tetrahedral intermediate. Aspartate and histidine function in acid-base catalysis by accepting and donating hydrogen atoms to stabilize the reaction.
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Ligand Interaction
Pancreatic lipase is shown here in a complex with the coenzyme colipase, which enhances lipase's function. The two identical lipase chains are pictured in pink and blue. The two identical chains of colipase are pictured in yellow and green. Three ligands are shown in association with the two lipase chains. Two calcium ions are shown in green as space-filling balls. Beta-mercaptoethanol is also shown as yellow, grey, and red balls. Lastly, (hydroxyethyloxy)tri(ethyloxy)octane is pictured as the larger grey, white, and red ball cluster directly in the middle of each of the lipase chains.
