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Subscriber access provided by UNIV OF CALIFORNIA CDL ACQUISITIONS Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Article Strictosidine Synthase: Mechanism of a Pictet Spengler Catalyzing Enzyme Justin J. Maresh, Lesley-Ann Giddings, Anne Friedrich, Elke A. Loris, Santosh Panjikar, Bernhardt L. Trout, Joachim Stckigt, Baron Peters, and Sarah E. O'Connor J. Am. Chem. Soc. , 2008 , 130 (2), 710-723• DOI: 10.1021/ja077190z • Publication Date (Web): 15 December 2007 Downloaded from http://pubs.acs.org on May 14, 2009 More About This Article Additional resources and features associated with this article are available within the HTML version: Supporting Information Links to the 4 articles that cite this article, as of the time of this article download Access to high resolution figures Links to articles and content related to this article Copyright permission to reproduce figures and/or text from this article
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Strictosidine Synthase: Mechanism of a Pictet - Spengler Catalyzing Enzyme ² Justin J. Maresh, ² Lesley-Ann Giddings, ² Anne Friedrich, ² Elke A. Loris, Santosh Panjikar, § Bernhardt L. Trout, | Joachim Sto ¨ckigt,* ,‡ Baron Peters,* , and Sarah E. O’Connor* Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, College of Pharmaceutical Sciences, Zhejiang Uni V ersity, Zijingang Campus, 310058 Hangzhou, China, Lehrstuhl fu ¨r Pharmazeutische Biologie, Institut fu ¨r Pharmazie, Staudingerweg 5, 55099 Mainz, Germany, European Molecular Biology Laboratory, Hamburg outstation DESY, Notkestrasse 85, 22603 Hamburg, Germany, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemical Engineering, Uni V ersity of California, Santa Barbara, Santa Barbara, California 93106 Received September 17, 2007; E-mail: . Abstract: The Pictet - Spengler reaction, which yields either a ± -carboline or a tetrahydroquinoline product from an aromatic amine and an aldehyde, is widely utilized in plant alkaloid biosynthesis. Here we deconvolute the role that the biosynthetic enzyme strictosidine synthase plays in catalyzing the stereose- lective synthesis of a ± -carboline product. Notably, the rate-controlling step of the enzyme mechanism, as identified by the appearance of a primary kinetic isotope effect (KIE), is the rearomatization of a positively charged intermediate. The KIE of a nonenzymatic Pictet - Spengler reaction indicates that rearomatization is also rate-controlling in solution, suggesting that the enzyme does not significantly change the mechanism of the reaction. Additionally, the pH dependence of the solution and enzymatic reactions provides evidence for a sequence of acid - base catalysis steps that catalyze the Pictet - Spengler reaction. An additional acid-catalyzed step, most likely protonation of a carbinolamine intermediate, is also significantly rate
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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.

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