Adenylosuccinate Synthetase: Difference between revisions
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==Structure== | ==Structure== | ||
The AdSS enzyme is a dimer consisting of two identical monomeric subunits. The main structural component of each monomer is a centrally located beta sheet that is comprised of 10 strands. Nine of the 10 strands are parallel while the 10th strand is anti-parallel with respect to the other 9 strands. There are also several other secondary structures including 2 small 3/10 helices and two anti-parallel sheets consisting of 2 and 3 strands respectively. Additionally there are 11 alpha helices.<ref>PMID:8244965</ref> AdSS has three major binding sites, one for GTP, one for IMP and its active site. The active site, in yellow, and ligand molecules in orange can be seen <scene name='Sandbox_187/Active_site_and_ligand/1'>here</scene> | The AdSS enzyme is a dimer consisting of two identical monomeric subunits. The main structural component of each monomer is a centrally located beta sheet that is comprised of 10 strands. Nine of the 10 strands are parallel while the 10th strand is anti-parallel with respect to the other 9 strands. There are also several other secondary structures including 2 small 3/10 helices and two anti-parallel sheets consisting of 2 and 3 strands respectively. Additionally there are 11 alpha helices.<ref>PMID:8244965</ref> AdSS has three major binding sites, one for GTP, one for IMP and its active site. The active site, in yellow, and ligand molecules in orange can be seen <scene name='Sandbox_187/Active_site_and_ligand/1'>here</scene>. | ||
The major fold of this protein is unique and has not been documented in any other type of protein. The active site itself consists of the following residues: Gly12, Gly15, Gly17, Lys18, Ile19, and Lys331. Lysine 140 and Arg147 are located in the region between the two monomers. Asp231 is bonded to Lys140 in a salt bridge and its carbonyl atom is bonded to Arg147. | |||
Helices are highlighted in green <scene name='Sandbox_187/Green_helices/1'>here</scene> and beta sheets are shown in orange <scene name='Sandbox_187/Beta_sheets/1'>here</scene>. | Helices are highlighted in green <scene name='Sandbox_187/Green_helices/1'>here</scene> and beta sheets are shown in orange <scene name='Sandbox_187/Beta_sheets/1'>here</scene>. | ||