Sandbox 173: Difference between revisions
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As this ligand is bound in the 12-s-''trans'' conformation, there arises the non-bonding interactions between the C-13 methyl group and C-10 hydrogen that contribute to non-planarity. This leads to the ability of the chromophore polyene tail to undergo fast photoisomerization around the C-11=C-12 double bond during light-induced activation<ref name="Article2">PMID:16962138</ref>. Also, it is found that the C-11=C-12 double bond is pre-twisted in the ground state of rhodopsin, which is partly attributed to the C20 methyl group attached to C13 through interaction with Tryptophan 265. This pre-twist may give insight on the features of isomerization about this bond upon light activation<ref name="ReferenceArticle"/>. | As this ligand is bound in the 12-s-''trans'' conformation, there arises the non-bonding interactions between the C-13 methyl group and C-10 hydrogen that contribute to non-planarity. This leads to the ability of the chromophore polyene tail to undergo fast photoisomerization around the C-11=C-12 double bond during light-induced activation<ref name="Article2">PMID:16962138</ref>. Also, it is found that the C-11=C-12 double bond is pre-twisted in the ground state of rhodopsin, which is partly attributed to the C20 methyl group attached to C13 through interaction with Tryptophan 265. This pre-twist may give insight on the features of isomerization about this bond upon light activation<ref name="ReferenceArticle"/>. | ||
Somewhat enclosing this chromophore is a retinal binding pocket partially formed by the N-terminal domain overlaying the extracellular turns including | Somewhat enclosing this chromophore is a retinal binding pocket partially formed by the N-terminal domain overlaying the extracellular turns including the second extracellular loop, which folds into the molecular center<ref name="Article6">PMID:18692154</ref>. | ||
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<applet load='1u19' size='300' color='black' frame='true' align='right' caption='Residues Involved in Activation of Rhodopsin. The generated structure is from Chain A.'/> | <applet load='1u19' size='300' color='black' frame='true' align='right' caption='Residues Involved in Activation of Rhodopsin. The generated structure is from Chain A.'/> | ||
====Photoisomeration of 11-''cis'' Retinal==== | ====Photoisomeration of 11-''cis'' Retinal==== | ||
The 11-''cis'' retinal (retinylidene) Schiff base functions as an [http://en.wikipedia.org/wiki/Inverse_agonist inverse agonist] and is prominently involved in the activation of rhodopsin. The primary step in rhodopsin photoactivation occurs in the photoisomeration of rhodopsin, as light energy absorbed from a photon is converted into chemical energy | The 11-''cis'' retinal (retinylidene) Schiff base functions as an [http://en.wikipedia.org/wiki/Inverse_agonist inverse agonist] and is prominently involved in the activation of rhodopsin. The primary step in rhodopsin photoactivation occurs in the photoisomeration of rhodopsin, as light energy absorbed from a photon is converted into chemical energy. As a photon is absorbed by the retina, the 11-''cis'' retinylidene ligand is switched into an all-''trans'' retinal configuration<ref name="Article2"/>. In this extremely efficient <200 fs process, the protein-binding pocket, initially fitted to accommodate the 11-''cis'' conformation of the chromophore, is preserved, which restrains the relaxation of the chromophore. The strained relaxation of conformational energy changes the protein state into the active form<ref name="Article2"/>. | ||
====Adjustment and Thermal Relaxation of the Protein==== | ====Adjustment and Thermal Relaxation of the Protein==== | ||