RuBisCO: Difference between revisions

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== Large Subunit Structure ==

This isolated <scene name='46/463261/Rubisco_lsu_pair/7'>pair of large subunits</scene> shows that each subunit has a large C-terminal lobe and a small N-terminal lobe, and the subunits are arranged head-to-toe (antiparallel). <scene name='46/463261/Rubisco_lsu_pair/5'>Two active sites</scene> are located in the interface of the large subunit pair. The subunits are shown in cartoon with one shown in the secondary structure color scheme. Each active site is occupied by RUBP, which is shown in CPK spacefill. Here is a <scene name='46/463261/Rubisco_lsu_monomer/1'>single large subunit</scene> showing that both lobes contain alpha helices (pink) and beta strands (yellow). The large lobe is dominated by an <scene name='46/463261/Rubisco_lsu_monomer/2'>α-β barrel</scene> (amino acids 166-409), which contributes most of the residues that form ~~the~~ the active site. One residue from the N-terminal lobe of the adjacent large subunit <scene name='46/463261/Asn123/1'>Asn 123</scene> completes the active site. This scene shows RUBP in spacefill and CPK in one of the active sites in the dimer. Both subunits are shown in transparent cartoon with the α-β barrel is pink and yellow. Asn 123 from the adjacent subunit is in blue spacefill, and residues 121-129 are shown in blue cartoon. This residue does not contribute to catalysis, and it will not be considered further.

This isolated <scene name='46/463261/Rubisco_lsu_pair/7'>pair of large subunits</scene> shows that each subunit has a large C-terminal lobe and a small N-terminal lobe, and the subunits are arranged head-to-toe (antiparallel). <scene name='46/463261/Rubisco_lsu_pair/5'>Two active sites</scene> are located in the interface of the large subunit pair. The subunits are shown in cartoon with one shown in the secondary structure color scheme. Each active site is occupied by RUBP, which is shown in CPK spacefill. Here is a <scene name='46/463261/Rubisco_lsu_monomer/1'>single large subunit</scene> showing that both lobes contain alpha helices (pink) and beta strands (yellow). The large lobe is dominated by an <scene name='46/463261/Rubisco_lsu_monomer/2'>α-β barrel</scene> (amino acids 166-409), which contributes most of the residues that form the active site. One residue from the N-terminal lobe of the adjacent large subunit <scene name='46/463261/Asn123/1'>Asn 123</scene> completes the active site. This scene shows RUBP in spacefill and CPK in one of the active sites in the dimer. Both subunits are shown in transparent cartoon with the α-β barrel is pink and yellow. Asn 123 from the adjacent subunit is in blue spacefill, and residues 121-129 are shown in blue cartoon. This residue does not contribute to catalysis, and it will not be considered further.

== Active Site Structure ==

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<scene name='46/463261/8ruc_active-site/10'>Residues that are involved in catalysis</scene> are shown shown here in CPK ball & stick. Asp 203 and Glu 204 bind to and position the magnesium ion. The carbamylated lysine residue KCX 201 coordinates Mg2+ and initiates catalysis by extracting a proton from C3 of RUBP. Note the proximity of the carbamyl group to carbon 3 in this structure. His 294 acts as a catalytic base in the carboxylation step of the mechanism and accepts a proton from the hydroxyl of carbon 3. Mg2+ is coordinated by six ligands. In addition to oxygen atoms in the three residues already mentioned, the ion binds to two oxygen atoms of RUBP. The 6th ligand is either water or in the carboxylation step it binds the incoming CO2. In the structure shown, Mg2+ is bound to the carboxyl group in CAP that corresponds to the fixed CO2 in the hydrated intermediate.</StructureSection>

== 3D Structures of RuBisCO ==

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@@ Line 12: / Line 12: @@
 == Large Subunit Structure ==
-This isolated <scene name='46/463261/Rubisco_lsu_pair/7'>pair of large subunits</scene> shows that each subunit has a large C-terminal lobe and a small N-terminal lobe, and the subunits are arranged head-to-toe (antiparallel). <scene name='46/463261/Rubisco_lsu_pair/5'>Two active sites</scene> are located in the interface of the large subunit pair. The subunits are shown in cartoon with one shown in the secondary structure color scheme. Each active site is occupied by RUBP, which is shown in CPK spacefill. Here is a <scene name='46/463261/Rubisco_lsu_monomer/1'>single large subunit</scene> showing that both lobes contain alpha helices (pink) and beta strands (yellow). The large lobe is dominated by an <scene name='46/463261/Rubisco_lsu_monomer/2'>α-β barrel</scene> (amino acids 166-409), which contributes most of the residues that form the the active site. One residue from the N-terminal lobe of the adjacent large subunit <scene name='46/463261/Asn123/1'>Asn 123</scene> completes the active site. This scene shows RUBP in spacefill and CPK in one of the active sites in the dimer. Both subunits are shown in transparent cartoon with the α-β barrel is pink and yellow. Asn 123 from the adjacent subunit is in blue spacefill, and residues 121-129 are shown in blue cartoon. This residue does not contribute to catalysis, and it will not be considered further.
+This isolated <scene name='46/463261/Rubisco_lsu_pair/7'>pair of large subunits</scene> shows that each subunit has a large C-terminal lobe and a small N-terminal lobe, and the subunits are arranged head-to-toe (antiparallel). <scene name='46/463261/Rubisco_lsu_pair/5'>Two active sites</scene> are located in the interface of the large subunit pair. The subunits are shown in cartoon with one shown in the secondary structure color scheme. Each active site is occupied by RUBP, which is shown in CPK spacefill. Here is a <scene name='46/463261/Rubisco_lsu_monomer/1'>single large subunit</scene> showing that both lobes contain alpha helices (pink) and beta strands (yellow). The large lobe is dominated by an <scene name='46/463261/Rubisco_lsu_monomer/2'>α-β barrel</scene> (amino acids 166-409), which contributes most of the residues that form the active site. One residue from the N-terminal lobe of the adjacent large subunit <scene name='46/463261/Asn123/1'>Asn 123</scene> completes the active site. This scene shows RUBP in spacefill and CPK in one of the active sites in the dimer. Both subunits are shown in transparent cartoon with the α-β barrel is pink and yellow. Asn 123 from the adjacent subunit is in blue spacefill, and residues 121-129 are shown in blue cartoon. This residue does not contribute to catalysis, and it will not be considered further.
 == Active Site Structure ==
@@ Line 19: / Line 19: @@
 <scene name='46/463261/8ruc_active-site/10'>Residues that are involved in catalysis</scene> are shown shown here in CPK ball & stick. Asp 203 and Glu 204 bind to and position the magnesium ion. The carbamylated lysine residue KCX 201 coordinates Mg<sup>2+</sup> and initiates catalysis by extracting a proton from C3 of RUBP. Note the proximity of the carbamyl group to carbon 3 in this structure. His 294 acts as a catalytic base in the carboxylation step of the mechanism and accepts a proton from the hydroxyl of carbon 3. Mg<sup>2+</sup> is coordinated by six ligands. In addition to oxygen atoms in the three residues already mentioned, the ion binds to two oxygen atoms of RUBP. The 6th ligand is either water or in the carboxylation step it binds the incoming CO<sub>2</sub>. In the structure shown, Mg<sup>2+</sup> is bound to the carboxyl group in CAP that corresponds to the fixed CO<sub>2</sub> in the hydrated intermediate.</StructureSection>
 == 3D Structures of RuBisCO ==