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Cape JL, Edson JB, Spencer LP, DeClue MS, Ziock HJ, Maurer S, Rasmussen S, Monnard PA, Boncella JM. Phototriggered DNA phosphoramidate ligation in a tandem 5'-amine deprotection/3'-imidazole activated phosphate coupling reaction. Bioconjug Chem 2012; 23:2014-9. [PMID: 22985338 DOI: 10.1021/bc300093y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the preparation and use of an N-methyl picolinium carbamate protecting group for applications in a phototriggered nonenzymatic DNA phosphoramidate ligation reaction. Selective 5'-amino protection of a modified 13-mer oligonucleotide is achieved in aqueous solution by reaction with an N-methyl-4-picolinium carbonyl imidazole triflate protecting group precursor. Deprotection is carried out by photoinduced electron transfer from Ru(bpy)(3)(2+) using visible light photolysis and ascorbic acid as a sacrificial electron donor. Phototriggered 5'- amino oligonucleotide deprotection is used to initiate a nonenzymatic ligation of the 13-mer to an imidazole activated 3'-phospho-hairpin template to generate a ligated product with a phosphoramidate linkage. We demonstrate that this methodology offers a simple way to exert control over reaction initiation and rates in nonenzymatic DNA ligation for potential applications in the study of model protocellular systems and prebiotic nucleic acid synthesis.
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Affiliation(s)
- Jonathan L Cape
- Material, Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Maurer SE, DeClue MS, Albertsen AN, Dörr M, Kuiper DS, Ziock H, Rasmussen S, Boncella JM, Monnard PA. Interactions between catalysts and amphiphilic structures and their implications for a protocell model. Chemphyschem 2011; 12:828-35. [PMID: 21344602 DOI: 10.1002/cphc.201000843] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Indexed: 11/09/2022]
Abstract
One of the essential elements of any cell, including primitive ancestors, is a structural component that protects and confines the metabolism and genes while allowing access to essential nutrients. For the targeted protocell model, bilayers of decanoic acid, a single-chain fatty acid amphiphile, are used as the container. These bilayers interact with a ruthenium-nucleobase complex, the metabolic complex, to convert amphiphile precursors into more amphiphiles. These interactions are dependent on non-covalent bonding. The initial rate of conversion of an oily precursor molecule into fatty acid was examined as a function of these interactions. It is shown that the precursor molecule associates strongly with decanoic acid structures. This results in a high dependence of conversion rates on the interaction of the catalyst with the self-assembled structures. The observed rate logically increases when a tight interaction between catalyst complex and container exists. A strong association between the metabolic complex and the container was achieved by bonding a sufficiently long hydrocarbon tail to the complex. Surprisingly, the rate enhancement was nearly as strong when the ruthenium and nucleobase elements of the complex were each given their own hydrocarbon tail and existed as separate molecules, as when the two elements were covalently bonded to each other and the resulting molecule was given a hydrocarbon tail. These results provide insights into the possibilities and constraints of such a reaction system in relation to building the ultimate protocell.
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Affiliation(s)
- Sarah E Maurer
- Center for Fundamental Living Technology, University of Southern Denmark, Campusvej 55, 5000 Odense C, Denmark
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DeClue MS, Monnard PA, Bailey JA, Maurer SE, Collis GE, Ziock HJ, Rasmussen S, Boncella JM. Nucleobase Mediated, Photocatalytic Vesicle Formation from an Ester Precursor. J Am Chem Soc 2008; 131:931-3. [DOI: 10.1021/ja808200n] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael S. DeClue
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - Pierre-Alain Monnard
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - James A. Bailey
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - Sarah E. Maurer
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - Gavin E. Collis
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - Hans-Joachim Ziock
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - Steen Rasmussen
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
| | - James M. Boncella
- Material, Physics and Applications Division, Earth and Environmental Sciences Division, Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545
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DeClue MS, Baldridge KK, Kast P, Hilvert D. Experimental and Computational Investigation of the Uncatalyzed Rearrangement and Elimination Reactions of Isochorismate. J Am Chem Soc 2006; 128:2043-51. [PMID: 16464106 DOI: 10.1021/ja056714x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The versatile biosynthetic intermediate isochorismate decomposes in aqueous buffer by two competitive pathways, one leading to isoprephenate by a facile Claisen rearrangement and the other to salicylate via elimination of the enolpyruvyl side chain. Computation suggests that both processes are concerted but asynchronous pericyclic reactions, with considerable C-O cleavage in the transition state but relatively little C-C bond formation (rearrangement) or hydrogen atom transfer to the enolpyruvyl side chain (elimination). Kinetic experiments show that rearrangement is roughly 8-times more favorable than elimination. Moreover, transfer of the C2 hydrogen atom to C9 was verified by monitoring the decomposition of [2-(2)H]isochorismate, which was prepared chemoenzymatically from labeled shikimate, by (2)H NMR spectroscopy and observing the appearance of [3-(2)H]pyruvate. Finally, the isotope effects obtained with the C2 deuterated substrate are in good agreement with calculations assuming pericyclic reaction mechanisms. These results provide a benchmark for mechanistic investigations of isochorismate mutase and isochorismate pyruvate lyase, the enzymes that respectively catalyze the rearrangement and elimination reactions in plants and bacteria.
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Affiliation(s)
- Michael S DeClue
- Laboratory of Organic Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
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Wright SK, DeClue MS, Mandal A, Lee L, Wiest O, Cleland WW, Hilvert D. Isotope effects on the enzymatic and nonenzymatic reactions of chorismate. J Am Chem Soc 2005; 127:12957-64. [PMID: 16159290 PMCID: PMC2519010 DOI: 10.1021/ja052929v] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The important biosynthetic intermediate chorismate reacts thermally by two competitive pathways, one leading to 4-hydroxybenzoate via elimination of the enolpyruvyl side chain, and the other to prephenate by a facile Claisen rearrangement. Measurements with isotopically labeled chorismate derivatives indicate that both are concerted sigmatropic processes, controlled by the orientation of the enolpyruvyl group. In the elimination reaction of [4-2H]chorismate, roughly 60% of the label was found in pyruvate after 3 h at 60 degrees C. Moreover, a 1.846 +/- 0.057 2H isotope effect for the transferred hydrogen atom and a 1.0374 +/- 0.0005 18O isotope effect for the ether oxygen show that the transition state for this process is highly asymmetric, with hydrogen atom transfer from C4 to C9 significantly less advanced than C-O bond cleavage. In the competing Claisen rearrangement, a very large 18O isotope effect at the bond-breaking position (1.0482 +/- 0.0005) and a smaller 13C isotope effect at the bond-making position (1.0118 +/- 0.0004) were determined. Isotope effects of similar magnitude characterized the transformations catalyzed by evolutionarily unrelated chorismate mutases from Escherichia coli and Bacillus subtilis. The enzymatic reactions, like their solution counterpart, are thus concerted [3,3]-sigmatropic processes in which C-C bond formation lags behind C-O bond cleavage. However, as substantially larger 18O and smaller 13C isotope effects were observed for a mutant enzyme in which chemistry is fully rate determining, the ionic active site may favor a somewhat more polarized transition state than that seen in solution.
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Affiliation(s)
- S Kirk Wright
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin, 1710 University Avenue, Madison, Wisconsin 53726, USA
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Abstract
Isochorismate pyruvate lyase (IPL) catalyzes the cleavage of isochorismate to give salicylate and pyruvate, a key step in bacterial siderophore biosynthesis. We investigated the enzyme from Pseudomonas aeruginosa using isochorismate selectively deuterated at C2 as a substrate. Monitoring the reaction by 2H NMR spectroscopy revealed that the label is quantitatively transferred from C2 to C9, producing stoichiometric amounts of [3-2H]pyruvate as product. Moreover, the deuterium kinetic isotope effect of 2.34 +/- 0.08 on kcat indicates that C-H cleavage is significantly rate limiting. Consistent with these data, hybrid density functional theory (HDFT) calculations at the Becke3LYP/DZ+(2d,p) level of theory predict a concerted but highly asynchronous pericyclic transition structure, in which carbon-oxygen bond cleavage is more advanced than hydrogen atom transfer from C2 to C9; the calculated 2H isotope effect of 2.22 at C2 is in excellent accord with the experimental value. Together, these findings indicate that IPL should be added to the small set of proteins that are known to catalyze pericyclic reactions. They also raise the possibility that enzymes, such as chorismate pyruvate lyase, salicylate synthase, 4-amino-4-deoxychorismate lyase, and anthranilate synthase, which accelerate formally similar reaction steps, may also exploit pericyclic mechanisms.
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Affiliation(s)
- Michael S DeClue
- Laboratory of Organic Chemistry, Swiss Federal Institute of Technology, ETH Hönggerberg, CH-8093 Zürich, Switzerland
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DeClue MS, Siegel JS. Polysiloxane-bound ligand accelerated catalysis: a modular approach to heterogeneous and homogeneous macromolecular asymmetric dihydroxylation ligands. Org Biomol Chem 2004; 2:2287-98. [PMID: 15305208 DOI: 10.1039/b406341d] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polysiloxane acts as a modular scaffold for macromolecular reagent development. Two separate components were covalently integrated into one material, one constituent provided reagent functionality, the other modulated solubility. In particular cinchona alkaloid based ligands used in the osmium tetroxide catalyzed asymmetric dihydroxylation (AD) reaction were covalently attached to commercially available polysiloxane. To enhance the reactivity of these polymeric ligands, multifunctional reagents were designed to include both the cinchona alkaloid and an alkoxyethylester solubilizing moiety providing random co-polymers. While the mono-functional materials led to heterogeneous conditions, the bi-functional polymers resulted in homogeneous reaction mixtures. Although both reagent types provided diol products with excellent yield and selectivity (>99% ee in nearly quantitative yield) the homogeneous analog has nearly twice the reactivity. Every repeat unit in the heterogeneous material was functionalized along the polysiloxane backbone while approximately half of these sites contained ligand in the homogeneous version. This approach led to macromolecular catalysts with high loadings of ligand and therefore materials with very low equivalent weights. Although these polymers are highly loaded they do maintain reactivity on a par with their free ligand counterpart. Using straightforward purification techniques (i.e. precipitation, simple filtration, or ultrafiltration) these polymeric ligands were easily separated from diol product and reused multiple times. Polysiloxane is a viable support for the catalysis of AD reactions and may provide a generally useful backbone for other catalytic systems.
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Affiliation(s)
- Michael S DeClue
- Department of Chemistry, University of California-San Diego, La Jolla 92093-0358, USA
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Wright D, Gubler U, Moerner WE, DeClue MS, Siegel JS. Photorefractive Properties of Poly(siloxane)-triarylamine-Based Composites for High-Speed Applications. J Phys Chem B 2003. [DOI: 10.1021/jp027456i] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Silvestri MG, Hanson MP, Pavlovich JG, Studen LF, DeClue MS, DeGraffenreid MR, Amos CD. Reactivity of Enol Carbonates with Ozone. J Org Chem 1999; 64:6597-6602. [PMID: 11674661 DOI: 10.1021/jo9824807] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several dienes of varying steric bulk containing an enol carbonate have been synthesized and reacted selectively with ozone at the isolated double bonds. Rate measurements have been made for ozonolysis in a series of substituted cyclohexenes to demonstrate the unusually slow reactivity of the enol carbonate. Proton and carbon NMR chemical shifts have been presented to show that the enol carbonate is not particularly electron deficient in its double bond. Calculation of partial charges from the Mulliken population analysis shows good correlation with the NMR data. The results suggest a carbonate association with ozone that slows the rate of carbon-carbon bond cleavage.
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Affiliation(s)
- Michael G. Silvestri
- Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, California 93407
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Bratcher MS, DeClue MS, Grunnet-Jepsen A, Wright D, Smith BR, Moerner WE, Siegel JS. Synthesis of Bifunctional Photorefractive Polymers with Net Gain: Design Strategy Amenable to Combinatorial Optimization. J Am Chem Soc 1998. [DOI: 10.1021/ja981473x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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