Lipase: Difference between revisions

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''~~'Structure of Horse Pancreatic~~ Lipase~~'''~~ <br />

A <scene name='Lipase/Lipase_starting_scene/2'>Lipase</scene> is a subclass of esterases which catalyzes the hydrolysis of ester bonds in lipid substrates and is essential for fat digestion. It is primarily produced in the pancreas, but can be found in the mouth and stomach as well. The lipase typically digests fat lipids into monoglycerides and free fatty acids, with the resulting monomers subsequently shuttled to the small intestine and eventually absorbed into the lymphatic system.

The ~~2D image (left)~~ and ~~3D image (right) are of a representative 3D lipase structure~~, ~~''i.e.''~~ the ~~biological unit of Horse pancreatic lipase [[1hpl]]~~.

==Lipase Catalytic Mechanism==

Although a diverse array of lipase enzymes are found in nature, occupying diverse protein scaffolds, most are built upon an alpha/beta hydrolase fold<ref>PMID: 1678899</ref><ref>PMID:1409539 </ref> and possess a [[chymotrypsin]]-like <scene name='Lipase/Catalytic_site_outerview/1'>catalytic triad </scene>comprised of an acidic residue, a histidine, and a serine nucleophile. In the case of the images above of a horse pancreatic lipase, the catalytic triad is comprised of <scene name='Lipase/Catalytic_triad/4'>Ser 152, Asp 176 and His 263. </scene><ref>PMID:8182745</ref>

This catalytic triad functions like most found in nature, first with the Aspartic acid forming a hydrogen bond with His 263, increasing the pKa of the histidine imidazole nitrogen. This allows the Histidine to act as a powerful general base and deprotonate the serine. The deprotonated serine then can serve as a nucleophile and attack the glycerol backbone of the lipid substrate. A water molecule then donates a proton to the histidine, creating a reactive hydroxyl anion, which can attack the carbonyl carbon of the lipid, releasing the catalytic serine and creating monoglyceride and fatty acid monomers that diffuse away.

~~== Lipase ==~~

A <scene name='Lipase/Lipase_starting_scene/2'>Lipase</scene> is a subclass of esterases which catalyzes the hydrolysis of ester bonds in lipid substrates and is essential for fat digestion. It is primarily produced in the pancreas, but can be found in the mouth and stomach as well. The lipase typically digests fat lipids into monoglycerides and free fatty acids, with the resulting monomers subsequently shuttled to the small intestine and eventually absorbed into the lymphatic system.

Although a diverse array of lipase enzymes are found in nature, occupying diverse protein scaffolds, most are built upon an alpha/beta hydrolase fold<ref>PMID: 1678899</ref><ref>PMID:1409539 </ref> and possess a [[chymotrypsin]]-like <scene name='Lipase/Catalytic_site_outerview/1'>catalytic triad </scene>comprised of an acidic residue, a histidine, and a serine nucleophile. In the case of the images above of a horse pancreatic lipase, the catalytic triad is comprised of <scene name='Lipase/Catalytic_triad/4'>Ser 152, Asp 176 and His 263. </scene><ref>PMID:8182745</ref>

This catalytic triad functions like most found in nature, first with the Aspartic acid forming a hydrogen bond with His 263, increasing the pKa of the histidine imidazole nitrogen. This allows the Histidine to act as a powerful general base and deprotonate the serine. The deprotonated serine then can serve as a nucleophile and attack the glycerol backbone of the lipid substrate. A water molecule then donates a proton to the histidine, creating a reactive hydroxyl anion, which can attack the carbonyl carbon of the lipid, releasing the catalytic serine and creating monoglyceride and fatty acid monomers that diffuse away.

== 3D Structures of Lipase ==

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 <applet load='1hpl3.pdb' size='300' frame='true' align='right' scene="Lipase/Lipase_starting_scene/2" caption='Crystal Structure of Horse Pancreatic Lipase, [[1hpl]]' />
-'''Structure of Horse Pancreatic Lipase''' <br />
+A <scene name='Lipase/Lipase_starting_scene/2'>Lipase</scene> is a subclass of esterases which catalyzes the hydrolysis of ester bonds in lipid substrates and is essential for fat digestion. It is primarily produced in the pancreas, but can be found in the mouth and stomach as well. The lipase typically digests fat lipids into monoglycerides and free fatty acids, with the resulting monomers subsequently shuttled to the small intestine and eventually absorbed into the lymphatic system.
-The 2D image (left) and 3D image (right) are of a representative 3D lipase structure, ''i.e.'' the biological unit of Horse pancreatic lipase [[1hpl]].
 {{TOC limit|limit=2}}
+==Lipase Catalytic Mechanism==
+Although a diverse array of lipase enzymes are found in nature, occupying diverse protein scaffolds, most are built upon an alpha/beta hydrolase fold<ref>PMID: 1678899</ref><ref>PMID:1409539 </ref>  and possess a [[chymotrypsin]]-like <scene name='Lipase/Catalytic_site_outerview/1'>catalytic triad </scene>comprised of an acidic residue, a histidine, and a serine nucleophile. In the case of the images above of a horse pancreatic lipase, the catalytic triad is comprised of <scene name='Lipase/Catalytic_triad/4'>Ser 152, Asp 176 and His 263. </scene><ref>PMID:8182745</ref>
+This catalytic triad functions like most found in nature, first with the Aspartic acid forming a hydrogen bond with His 263, increasing the pKa of the histidine imidazole nitrogen. This allows the Histidine to act as a powerful general base and deprotonate the serine. The deprotonated serine then can serve as a nucleophile and attack the glycerol backbone of the lipid substrate. A water molecule then donates a proton to the histidine, creating a reactive hydroxyl anion, which can attack the carbonyl carbon of the lipid, releasing the catalytic serine and creating monoglyceride and fatty acid monomers that diffuse away.
-== Lipase ==
-A <scene name='Lipase/Lipase_starting_scene/2'>Lipase</scene> is a subclass of esterases which catalyzes the hydrolysis of ester bonds in lipid substrates and is essential for fat digestion. It is primarily produced in the pancreas, but can be found in the mouth and stomach as well. The lipase typically digests fat lipids into monoglycerides and free fatty acids, with the resulting monomers subsequently shuttled to the small intestine and eventually absorbed into the lymphatic system.
-Although a diverse array of lipase enzymes are found in nature, occupying diverse protein scaffolds, most are built upon an alpha/beta hydrolase fold<ref>PMID: 1678899</ref><ref>PMID:1409539 </ref>  and possess a [[chymotrypsin]]-like <scene name='Lipase/Catalytic_site_outerview/1'>catalytic triad </scene>comprised of an acidic residue, a histidine, and a serine nucleophile. In the case of the images above of a horse pancreatic lipase, the catalytic triad is comprised of <scene name='Lipase/Catalytic_triad/4'>Ser 152, Asp 176 and His 263. </scene><ref>PMID:8182745</ref>
-This catalytic triad functions like most found in nature, first with the Aspartic acid forming a hydrogen bond with His 263, increasing the pKa of the histidine imidazole nitrogen. This allows the Histidine to act as a powerful general base and deprotonate the serine. The deprotonated serine then can serve as a nucleophile and attack the glycerol backbone of the lipid substrate. A water molecule then donates a proton to the histidine, creating a reactive hydroxyl anion, which can attack the carbonyl carbon of the lipid, releasing the catalytic serine and creating monoglyceride and fatty acid monomers that diffuse away.
 == 3D Structures of Lipase ==