Human Cardiac Troponin C: Difference between revisions

{{STRUCTURE_2kdh|PDB=2kdh|<scene name='Human_Cardiac_Troponin_C/2kdh_troponin_c/3'>TextToBeDisplayed</scene>}}

[[Image:2kdh.png|left|200px]]

[[2KDH]] is the Solution Structure of Human Cardiac Troponin C in complex with the Green Tea Polyphenol :  (-)-epigallocatechin-3-gallate. It is a 1 chain structure of sequence from [http://fr.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. That is the PDB name for the solution  structure of Human Cardiac Troponin C in complex with the green tea Polyphenol (-)-epigallocatechin-3-gallate.  

For example, heart muscle contraction is regulated by Ca2+ binding of troponin C to the thin filament. In cardiovascular diseases, the myofilament response to Ca2+ is often altered. Compounds that rectify this perturbation are of considerable interest as therapeutics. Plant [http://en.wikipedia.org/wiki/Flavonoid flavonoids] have been found to provide protection against a variety of human illnesses such as cancers, infections, and heart diseases. (-)-Epigallocatechin gallate (EGCg), the prevalent flavonoid in green tea is one of those plant flavonoids.

<scene name='User:Alicia_Daeden/Sandbox_130/Sheets/1'>two sheets</scene> which are anti-parallel. This structure appears on the [http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?template=main.html&o=PROCHECK&c=999&pdbcode=2kdh Ramachandran plot], where can be observed a high concentration of residues (amino acids) in the energy level located in: Psi 0-(-45), Phi -90-(-45), which is the level of energy the most favorable to the constitution of helices. On the contrary, only few residues are in the level of energy corresponding to the sheet:Psi 90-180, Phi -135-(-45), actually there are only 2 little sheets. There are some residues in: Psi 0-90, Phi 45-90, which are involved in loops permitting bounds between sheets and helices. Four of those residues are glycins which permit those loops because of their low steric dimensions. In fact, glycin with it radical chain composed of one hydrogen allows easily change of direction of the protein. It's one of amino acids the most privileged in those kinds of structure.

There are <scene name='User:Alicia_Daeden/Sandbox_130/Hydrophobic/1'>hydrophobic residues</scene> which form an hydrophobic pocket.EGCg interacts with AC3 hydrophobic domain of the molecule  and binds with AC2 domain. But there are <scene name='User:Alicia_Daeden/Sandbox_130/Residues_of_beta-sheet/1'> some residues of beta-sheet</scene> wich have no interactions with that molecule and this suggets that the binding of EGCg is near of the hydrophobic pocket rather than deep within the pocket and it induces a small structural "opening". The opening degree of TnC is described by the inter-helical angles between helices E and F and between helices G and H.

[[Image:EGC-TnC.jpg|350px]] '''''EGCg-TnC complex'''''

As said just before, EGCg makes contacts exclusively to hydrophobic residues that line the surface of TnC. Actually it binds near the surface of helix E, so near the N-terminus of TnC, with tetrahydropyran and benzenediol. The pyrogallol ring stays near the C-terminus of TnC, which explains the large chemical shift perturbations of some residues of the <scene name='User:Alicia_Daeden/Sandbox_130/Helix_h/1'>helix H</scene>.