Sandbox 250: Difference between revisions

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Joel L. Sussman, Allison Granberry, Jaime Prilusky

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 ==='''Introduction'''===
-Acetylcholinesterase(AChE) is essential for the hydrolysis of the neurotransmitter acetylcholine (ACh), and therefore the termination of the nerve impulse in cholinergic synapses (Figure 2). Irreversible inhibition of AChE can lead to increased levels of ACh in cholinergic synapses and ultimately death. Conversely, suppressed levels of ACh may lead to memory deficits associated with Alzheimer's disease <ref>PMID: 14501022</ref>. AChE has a deep (20Å) and narrow (5Å) gorge lined with 14 aromatic residues, with its active site at the bottom of the gorge<ref>PMID: 1678899</ref>. Initially, ACh binds to the peripheral anionic site(PAS)  of AChE and is funneled down the gorge to the active site by interactions between the aromatic rings of the 14 aromatic residues and the quaternary ammonium ion of ACh. At the active site, ACh is oriented for hydrolysis by interactions between the catalytic anionic ion site and the quaternary ammonium ion of ACh. The Fasciculin-II (FAS-II)toxin, a component of the East African Green Mamba snake(''Dendroaspis angusticeps'') venom, inhibits AChE by binding to the top of the active-site gorge, including residues that form the PAS; thus preventing ACh from entering the active-site gorge<ref>PMID:8747462</ref>. The Hostos-Lincoln Academy Students Modeling A Research Topic (S.M.A.R.T) team and the Center for BioMolecular Modeling have designed and fabricated two physical models using a combination of computational molecular modeling and three-dimensional(3D) printing technology: ''Torpedo californica'' (''Tc'') AChE in complex with a modeled ACh ligand and ''Tc''AChE in complex with FAS-II.
+Acetylcholinesterase(AChE) is essential for hydrolysis of the neurotransmitter acetylcholine (ACh), and, therefore, for termination of impulse transmission at cholinergic synapses (Figure 2). Irreversible inhibition of AChE can result in accumulation of ACh at cholinergic synapses and, ultimately, to death. Conversely, decreased levels of ACh may result in the memory deficits associated with Alzheimer's disease <ref>PMID: 14501022</ref>. AChE has a deep (20Å) and narrow (5Å) gorge lined with 14 aromatic residues, with its active site located near the bottom of the gorge<ref>PMID: 1678899</ref>. Initially, ACh binds to the peripheral anionic site (PAS) of AChE, and is funneled down the gorge to the active site by interactions between its quaternary ammonium group and the aromatic rings of 14 aromatic amino acid residues lining the gorge. At the active site, ACh is oriented for hydrolysis by interactions between the catalytic anionic site and its quaternary ammonium group. Fasciculin-II (FAS-II), a potent polypeptide toxin present in the venom of the East African green mamba (Dendroaspis angusticeps), inhibits AChE by binding to the top of the active-site gorge, interacting tightly with residues that form the PAS; it thus prevents ACh from entering the active-site gorge<ref>PMID:8747462</ref>. The Hostos-Lincoln Academy Students Modeling A Research Topic (S.M.A.R.T) team and the Center for BioMolecular Modeling have designed and fabricated two physical models using a combination of computational molecular modeling and three-dimensional (3D) printing technology: "Torpedo californica" ("Tc") AChE complexed with a modeled ACh molecule ligand, and a complex of FAS-II with "Tc"AChE.
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