Sandbox108
From Proteopedia
Glutamine synthetase assignment by UMBC undergraduate students(Not Complete version)
Glutamine synthetase of Salmonella typhimurium
Tertiary structure of protein is characterized by the “global” folding of a polypeptide chain [1] and mostly affected by () interaction and hydrogen bonding. In general, hydrophobic interaction is a major driving force determining the most tertiary structure of the proteins. Hydrogen bonding is crucial in stabilizing the tertiary structure as well.[2] Also, disulfide bonds between cysteine residues stabilize the tertiary structure. [3] However, for Salmonella typhimurium it is mainly influenced by the helix-helix interaction between two layers, as well as 12-subunits enzymes.[4]
Glutamine synthetase from Salmonella typhimurium is the 12-subunits enzyme and has 23 helix-helix interactions involving helices of chain A with four different types of interactions. [5] The 12-subunits enzyme are arranged in two layers of six, such as in the one of the protein residues of Salmonella typhimurium; at the interface of pairs of subunits within each layer, six anti-parallel beta strands formed cylindrical active sites.[6] Each active site holds two ions surrounded by some [7] Also, the protein ligands to Mn2+ 469 are , , and ; those to Mn2+ 470 are , , and .[8] In glutamine from Salmonella typhimurium, there are 12-subunits of each of them in pairs within two layers. COOH terminus, a helical thong, which inserts into a pocket formed by two neighboring subunits on the opposite ring, hold the two layers of subunits tightly.[9] Also, even though there is a between layers, interactions will contribute to the stability of the intersubunit.[10] However, the most effective interaction in glutamine synthetase from Salmonella typhimurium is the helix-helix interactions. The folding of the proteins can be affected by the 12-subunits in the residues, as well as the helix-helix interactions. However, for Salmonella typhimurium the helices of chain A has , while most glutamine has uncharged side chain which formed by replacing the hydroxyl of glutamic acid with an amine functional group. Also, the only helix-helix interactions will be the most powerful sources of being in the glutamine synthetase of Salmonella typhimurium.
