Sandbox2qc8
Glutamine Synthetase: Secondary structuresGlutamine Synthetase: Secondary structures
Glutamine synthetase is composed of 12 . Each subunit is composed of 15 and 15 . Each subunit binds 2 Mn for a total of per Glutamine Synthetase.
The β-strands are arranged into 5 . In addition, there are 5 and 5 . [1] β-bulges are distortions in β-sheets resulting from the addition of an extra residue due to mutation. Their presence allows the proteins to conserve their structure by maintaining the hydrogen bond pattern.[2] At the level of the backbone structure, these β-bulges can cause a simple aneurysm of the β-sheet. Furthermore, each β-bulge can cause a β-sheet to fold over and cross itself.
Within each subunit there are 46 β-turns. These β-turns join secondary structures such as β-sheets and alpha helices when they need to abruptly change directions and usually occur at the protein surface.[2]
Glutamine Synthetase is covalently modified by the addition of Adenosine monophosphate at Tyrosine 397 which is contained in the [3]. In addition, β-loops protrude into the , allowing for additional quaternary stability.[4]
Each subunit has an exposed NH2 terminus and buried COOH terminus as part of a , colored in red. The helical thong is used as an anchor inside another subunit. [4]
The active site within the secondary structure can be called a "bifunnel," providing access to ATP and glutamate at opposing ends.[5]
The only ligand present is a pair of Mn ions (Manganese) that indicates the active site of each subunit of the dodecamer.
Glutamine synthetase contains the .
ReferencesReferences
- ↑ European Bioinformatics Institute, Ligase(amide synthetase), http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=2gls, Accessed December 18, 2008.
- ↑ 2.0 2.1 Donald Voet, Judith G. Voet, Charlotte W. Pratt. Fundamentals of Biochemistry life at the molecular level. New Jersey: Wiley,2006.
- ↑ Eisenberg, D., et.al., Structure-function relationships of glutamine synthetases, Biochim Biophys Acta 2000: 1477, 122-145
- ↑ 4.0 4.1 Yamashita, M. M., et.al., Refined Atolnic Model of Glutamine Synthetase at 3.5 A Resolution, J Biol Chem 1989 264: 17681-17690.
- ↑ Eisenberg, D., et al., Structure-function relationships of glutamine synthetases, Biochimica et Biophysica Acta 1477 (2000), 122-145.