Sandbox 212: Difference between revisions

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The <scene name='Sandbox_212/Active_site/1'>active site</scene> of CrAT is located at the interface between the N and C domains. Biochemical and mutagenesis studies have permitted to identify a <scene name='Sandbox_212/Histidine343/1'> histidine residue as the catalytic base </scene> of carnitine acyltransferases. It can be reached from two openings of the tunnel on the surface of the structure. One of these openings is used for binding carnitine, while the other is used for binding CoA. Hence, the two substrates of the enzyme bind at opposite sides of the catalytic residue.

* '''carnitine binding site'''

The carnitine substrate has to be positioned in a way that the proton of its hydroxyl group can interact with the nitrogen N3 of the catalytic residue histidine 343. Carnitine binding in the right position is made possible by electrostatic interactions and the formation of hydrogen bondings between the '''carboxylate group''' of carnitine and ~~residues near the~~ active site. The residues that form the carnitine binding site can be found in the C domain and in the N domain.

The carnitine substrate has to be positioned in a way that the proton of its hydroxyl group can interact with the nitrogen N3 of the catalytic residue histidine 343. Carnitine binding in the right position is made possible by electrostatic interactions and the formation of hydrogen bondings between the '''carboxylate group''' of carnitine and active site residues. The residues that form the carnitine binding site can be found in the C domain and in the N domain.

The main <scene name='Sandbox_212/Hydrogen_bonding_residues/3'>residues involved in hydrogen-bonding interactions </scene> are '''tyrosine452''', '''serine454''', and '''threonine465'''. They possess side chain hydroxyls which can interact with the carboxylic oxygen atoms of carnitine. One of the carboxylic oxygen atoms is also hydrogen-bonded to a '''water molecule '''<ref name="structure">PMID: 12526798</ref> Electrostatic interactions are formed by the carboxylate group of carnitine with the side chain guanidinium group of an arginine residue.

The exact role of the '''trimethylammonium group''' during carnitine binding hasn’t been fully revealed yet. Carnitine is rather required for catalysis than for binding. Even though the trimethylammonium group has a positive charge on its nitrogen it is not surrounded by negatively charged residues which could balance it. Instead, the trimethylammonium group is situated in a rather hydrophobic environment.

Sandbox 212: Difference between revisions

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@@ Line 34: / Line 34: @@
 The <scene name='Sandbox_212/Active_site/1'>active site</scene> of CrAT is located at the interface between the N and C domains. Biochemical and mutagenesis studies have permitted to identify a <scene name='Sandbox_212/Histidine343/1'> histidine residue as the catalytic base </scene> of carnitine acyltransferases. It can be reached from two openings of the tunnel on the surface of the structure. One of these openings is used for binding carnitine, while the other is used for binding CoA. Hence, the two substrates of the enzyme bind at opposite sides of the catalytic  residue.
 * '''carnitine binding site'''
-The carnitine substrate has to be positioned in a way that the proton of its hydroxyl group can interact with the nitrogen N3 of the catalytic residue histidine 343. Carnitine binding in the right position is made possible by electrostatic interactions and the formation of hydrogen bondings between the '''carboxylate group''' of carnitine and residues near the active site. The residues that form the carnitine binding site can be found in the C domain and in the N domain.
+The carnitine substrate has to be positioned in a way that the proton of its hydroxyl group can interact with the nitrogen N3 of the catalytic residue histidine 343. Carnitine binding in the right position is made possible by electrostatic interactions and the formation of hydrogen bondings between the '''carboxylate group''' of carnitine and active site residues. The residues that form the carnitine binding site can be found in the C domain and in the N domain.
 The main <scene name='Sandbox_212/Hydrogen_bonding_residues/3'>residues involved in  hydrogen-bonding interactions </scene> are  <font color='#0000FF'>'''tyrosine452'''</font>, <font color='#90E050'>'''serine454'''</font>, and <font color='#FF0D0D'>'''threonine465'''</font>. They possess side chain hydroxyls which can interact with the carboxylic oxygen atoms of carnitine. One of the carboxylic oxygen atoms is also hydrogen-bonded to a <font color='#00007C'>'''water molecule '''</font><ref name="structure">PMID: 12526798</ref> Electrostatic interactions are formed by the carboxylate group of carnitine with the side chain guanidinium group of an arginine residue.
 The exact role of the '''trimethylammonium group''' during carnitine binding hasn’t been fully revealed yet. Carnitine is rather required for catalysis than for binding. Even though the trimethylammonium group has a positive charge on its nitrogen it is not surrounded by negatively charged residues which could balance it. Instead, the trimethylammonium group is situated in a rather hydrophobic environment.