Journal:Protein Science:1: Difference between revisions
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<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
The photosensitizer, <scene name='Journal:Protein_Science:1/Cv/3'>methylene blue (MB)</scene>, generates singlet oxygen that irreversibly inhibits Torpedo californica acetylcholinesterase (''Tc''AChE). In the dark, it inhibits reversibly. | The photosensitizer, <scene name='Journal:Protein_Science:1/Cv/3'>methylene blue (MB)</scene>, generates singlet oxygen that irreversibly inhibits Torpedo californica acetylcholinesterase (''Tc''AChE). In the dark, it inhibits reversibly. | ||
The ''Tc''AChE active site consists of two binding subsites. One of them is the "catalytic anionic site" (CAS), which involves the catalytic triad <scene name='Journal:Protein_Science:1/Cv/ | The ''Tc''AChE active site consists of two binding subsites. One of them is the "catalytic anionic site" (CAS), which involves the catalytic triad <scene name='Journal:Protein_Science:1/Cv/6'>Ser200, His440, and Glu327</scene> <font color='orange'><b>(colored orange)</b></font> and the conserved residues <scene name='2j3q/Active_site/3'>Trp84 and Phe330</scene> which also participate in ligand recognition. Another conserved residue <scene name='2j3q/Active_site/4'>Trp279</scene> <font color='cyan'><b>(colored cyan)</b></font> is situated at the second binding subsite, termed the "peripheral anionic site" (PAS), ~14 Å from CAS. <scene name='2j3q/Active_site/6'>Thioflavin T</scene> is a good example of the PAS-binding AChE inhibitors. <scene name='2j3q/Active_site/7'>Superposition</scene> of the crystal structure of the <font color='red'><b>edrophonium</b></font>/''Tc''AChE (mentioned above as a CAS-binding inhibitor) ([[2ack]]) on the <font color='magenta'><b>thioflavin T</b></font>/''Tc''AChE complex structure ([[2j3q]]) shows that these ligands' positions do not overlap. Of note is that Phe330, which is part of the CAS, is the single residue interacting with <font color='magenta'><b>thioflavin T</b></font>. This residue is the only one which significantly <scene name='2j3q/Active_site/9'>changes its conformation</scene> to avoid clashes in comparison to other CAS residues of the <font color='red'><b>edrophonium</b></font>/''Tc''AChE complex <ref name="Ravelli">PMID:10089512</ref> <ref name="Sonoda">PMID:18512913</ref>. | ||
Revision as of 09:27, 24 June 2012
<StructureSection load='2W9Ial.pdb' size='500' side='right' scene='Journal:Protein_Science:1/Cv/2' caption=>
Structural and functional characterization of the interaction of the photosensitizing probe methylene blue with Torpedo californica acetylcholinesterase
Aviv Paz, Esther Roth, Yacov Ashani, Yechun Xu, Valery L. Shnyrov, Joel L. Sussman, Israel Silman, and Lev Weiner[1]
Molecular Tour
The photosensitizer, methylene blue (MB), generates singlet oxygen that irreversibly inhibits Torpedo californica acetylcholinesterase (TcAChE). In the dark, it inhibits reversibly.
The TcAChE active site consists of two binding subsites. One of them is the "catalytic anionic site" (CAS), which involves the catalytic triad Ser200, His440, and Glu327 (colored orange) and the conserved residues Trp84 and Phe330 which also participate in ligand recognition. Another conserved residue Trp279 (colored cyan) is situated at the second binding subsite, termed the "peripheral anionic site" (PAS), ~14 Å from CAS. Thioflavin T is a good example of the PAS-binding AChE inhibitors. Superposition of the crystal structure of the edrophonium/TcAChE (mentioned above as a CAS-binding inhibitor) (2ack) on the thioflavin T/TcAChE complex structure (2j3q) shows that these ligands' positions do not overlap. Of note is that Phe330, which is part of the CAS, is the single residue interacting with thioflavin T. This residue is the only one which significantly changes its conformation to avoid clashes in comparison to other CAS residues of the edrophonium/TcAChE complex [2] [3].
- ↑ Paz A, Roth E, Ashani Y, Xu Y, Shnyrov VL, Sussman JL, Silman I, Weiner L. Structural and functional characterization of the interaction of the photosensitizing probe methylene blue with Torpedo californica acetylcholinesterase. Protein Sci. 2012 Jun 1. doi: 10.1002/pro.2101. PMID:22674800 doi:10.1002/pro.2101
- ↑ Ravelli RB, Raves ML, Ren Z, Bourgeois D, Roth M, Kroon J, Silman I, Sussman JL. Static Laue diffraction studies on acetylcholinesterase. Acta Crystallogr D Biol Crystallogr. 1998 Nov 1;54(Pt 6 Pt 2):1359-66. PMID:10089512
- ↑ Harel M, Sonoda LK, Silman I, Sussman JL, Rosenberry TL. Crystal structure of thioflavin T bound to the peripheral site of Torpedo californica acetylcholinesterase reveals how thioflavin T acts as a sensitive fluorescent reporter of ligand binding to the acylation site. J Am Chem Soc. 2008 Jun 25;130(25):7856-61. Epub 2008 May 31. PMID:18512913 doi:https://dx.doi.org/10.1021/ja7109822
