Sandbox 212: Difference between revisions

Line 29:

* '''overall structure'''

The structure of CrAT contains 16 β strands (β1–β16) and 20 α helices (α1–α20) and can be divided into two domains, a C domain and a N domain.<ref name="structure1"/> The shown 3D structure shows two molecules of carnitine acetyltransferases ~~und~~ thus two active sites as well as two carnitine binding sites.

The structure of CrAT contains 16 β strands (β1–β16) and 20 α helices (α1–α20) and can be divided into two domains, a C domain and a N domain.<ref name="structure1"/> The shown 3D structure shows two molecules of carnitine acetyltransferases and thus two active sites as well as two carnitine binding sites.

The core of the 2 domains is a 6-stranded mixed β-sheet (β10-β13, β15, β16 in the C domain), with 3 α-helices covering one of its faces (α6, α7, α12 in the N domain). The other face of the β-sheet in the N domain is covered by additional helices, whereas the other face of the β-sheet in the C domain is covered by the N domain.

* '''active site'''

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 histidine residue as the catalytic base 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 ~~<scene name='Sandbox_212/Histidine343/1'>~~ catalytic residue~~</scene>~~.

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.

Sandbox 212: Difference between revisions

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 <StructureSection load='1ndf' size='500' side='right' caption='Structure of carnitine acetyltransferase in complex with carnitine (PDB entry [[1ndf]])' scene='Sandbox_212/Carnitine_acyltransferase/1'>
 * '''overall structure'''
-The structure of CrAT contains 16 β strands (β1–β16) and 20 α helices (α1–α20) and can be divided into two domains, a C domain and a N domain.<ref name="structure1"/> The shown 3D structure shows two molecules of carnitine acetyltransferases und thus two active sites as well as two carnitine binding sites.
+The structure of CrAT contains 16 β strands (β1–β16) and 20 α helices (α1–α20) and can be divided into two domains, a C domain and a N domain.<ref name="structure1"/> The shown 3D structure shows two molecules of carnitine acetyltransferases and thus two active sites as well as two carnitine binding sites.
 The core of the 2 domains is a 6-stranded mixed β-sheet (β10-β13, β15, β16 in the C domain), with 3 α-helices covering one of its faces (α6, α7, α12 in the N domain). The other face of the β-sheet in the N domain is covered by additional helices, whereas the other face of the β-sheet in the C domain is covered by the N domain.
 * '''active site'''
-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 histidine residue as the catalytic base 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 <scene name='Sandbox_212/Histidine343/1'> catalytic  residue</scene>.
+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.