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 name=crystal>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=' | 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 name=crystal>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='38/382959/Cv/3'>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 a crevice consisting of Gly12, Gly15, Gly17, Lys18, Ile19, and Lys331. The other side of the crevice contains Lysine 140 and Arg147, which are located in the region between the two monomers. Asp231 is bonded to Lys140 in a salt bridge and its carbonyl atom is hydrogen bonded to Arg147. Also, none of cysteine residues are bound to each other in disulphide bonds.<ref name=crystal /> | 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 a crevice consisting of Gly12, Gly15, Gly17, Lys18, Ile19, and Lys331. The other side of the crevice contains Lysine 140 and Arg147, which are located in the region between the two monomers. Asp231 is bonded to Lys140 in a salt bridge and its carbonyl atom is hydrogen bonded to Arg147. Also, none of cysteine residues are bound to each other in disulphide bonds.<ref name=crystal /> | ||