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Unformatted text preview: Abstract: Strictosidine synthase diastereoselectively converts t ryptamine 1a and secologanin 2 to beta carboline product strictosidine 3. Strictosidine 3 serves as the biosynthetic precursor to all terpene indole alkaloids. Pictet-spengler rxn: 1. Electron-rich aromatic amine and an aldehyde condense to form an iminium species 2. Electrophilic aromatic substitution rxn, the aryl amine attacks the electrophilic iminium to yield a positively charged intermediate which is then deprotonated to yield the beta carboline products. Acid catalyzed step involved in iminium formation and base catalyzed step involved in the final deprotonation step. Strictosidine synthase: Crystal structure revealed the presence of only 3 ionizable residues in the active site: tyr151, his307, and glu309, located near the amine of t ryptamine 1 and the aldehyde of secologanin 2. Site directed mutagenesis to tyr151 : 1. suggests that the ionizable hydroxyl group does not play an important role in catalysis 2. support the involvement of glutamate residue in catalysis...
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This note was uploaded on 10/28/2010 for the course CHEM 157 taught by Professor burkart during the Spring '07 term at UCSD.
- Spring '07