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| {{STRUCTURE_1ce8| PDB=1ce8 | SCENE= }} | | {{STRUCTURE_1ce8| PDB=1ce8 | SCENE= }} |
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| '''CARBAMOYL PHOSPHATE SYNTHETASE FROM ESCHERICHIS COLI WITH COMPLEXED WITH THE ALLOSTERIC LIGAND IMP'''
| | ===CARBAMOYL PHOSPHATE SYNTHETASE FROM ESCHERICHIS COLI WITH COMPLEXED WITH THE ALLOSTERIC LIGAND IMP=== |
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| ==Overview==
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| Carbamoyl phosphate synthetase (CPS) from Escherichia coli catalyzes the formation of carbamoyl phosphate, which is subsequently employed in both the pyrimidine and arginine biosynthetic pathways. The reaction mechanism is known to proceed through at least three highly reactive intermediates: ammonia, carboxyphosphate, and carbamate. In keeping with the fact that the product of CPS is utilized in two competing metabolic pathways, the enzyme is highly regulated by a variety of effector molecules including potassium and ornithine, which function as activators, and UMP, which acts as an inhibitor. IMP is also known to bind to CPS but the actual effect of this ligand on the activity of the enzyme is dependent upon both temperature and assay conditions. Here we describe the three-dimensional architecture of CPS with bound IMP determined and refined to 2.1 A resolution. The nucleotide is situated at the C-terminal portion of a five-stranded parallel beta-sheet in the allosteric domain formed by Ser(937) to Lys(1073). Those amino acid side chains responsible for anchoring the nucleotide to the polypeptide chain include Lys(954), Thr(974), Thr(977), Lys(993), Asn(1015), and Thr(1017). A series of hydrogen bonds connect the IMP-binding pocket to the active site of the large subunit known to function in the phosphorylation of the unstable intermediate, carbamate. This structural analysis reveals, for the first time, the detailed manner in which CPS accommodates nucleotide monophosphate effector molecules within the allosteric domain.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10428826}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10428826 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10428826}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Allosteric ligand]] | | [[Category: Allosteric ligand]] |
| [[Category: Imp]] | | [[Category: Imp]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:37:57 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:37:21 2008'' |