スキップしてメイン コンテンツに移動

投稿

5月, 2016の投稿を表示しています

Anion‐π Enzymes

ACS Cent. Sci. , Article ASAP DOI: 10.1021/acscentsci.6b00097 Publication Date (Web): May 23, 2016   Yoann Cotelle † ‡ , Vincent Lebrun † § , Naomi Sakai † ‡ , Thomas R. Ward * † § , and Stefan Matile * † ‡ † National Centre of Competence in Research (NCCR) Molecular Systems Engineering , Basel, Switzerland ‡ Department of Organic Chemistry, University of Geneva , CH-1211 Geneva, Switzerland § Department of Chemistry, University of Basel , CH-4056 Basel, Switzerland    http://pubs.acs.org/doi/pdf/10.1021/acscentsci.6b00097 Abstract In this report, we introduce artificial enzymes that operate with anion-π interactions, an interaction that is essentially new to nature. The possibility to stabilize anionic intermediates and transition states on an π-acidic surface has been recently demonstrated, using the addition of malonate half thioesters to enolate acceptors as a biologically relevant example. The best chiral anion-π catalysts oper...

Asymmetric Enzymatic Synthesis of Allylic Amines: A Sigmatropic Rearrangement Strategy

Dr. Christopher K. Prier, Dr. Todd K. Hyster, Dr. Christopher C. Farwell, Audrey Huang, Prof. Dr. Frances H. Arnold First published:  11 March 2016 Full publication history DOI:  10.1002/ange.201601056 View/save citation Cited by:  0  articles   Check for new citations Abstract Sigmatropic rearrangements, while rare in biology, offer opportunities for the efficient and selective synthesis of complex chemical motifs. A “P411” serine-ligated variant of cytochrome P450 BM3  has been engineered to initiate a sulfimidation/[2,3]-sigmatropic rearrangement sequence in whole E. coli cells, a non-natural function for any enzyme, providing access to enantioenriched, protected allylic amines. Five mutations in the enzyme substantially enhance its activity toward this new function, demonstrating the evolvability of the catalyst toward challenging nitrene transfer reactions. The evolved catalyst...

Synthesis, Radical Reactivity, and Thermochemistry of Monomeric Cu(II) Alkoxide Complexes Relevant to Cu/Radical Alcohol Oxidation Catalysis

Thomas R. Porter ,  Dany Capitao ,  Werner Kaminsky ,  Zhaoshen Qian , and  James M. Mayer * Department of Chemistry,  University of Washington , Box 351700, Seattle, Washington 98195,  United States Inorg. Chem. , Article ASAP DOI:  10.1021/acs.inorgchem.6b00491 Publication Date (Web): May 12, 2016 Copyright © 2016 American Chemical Society Abstract Two new monomeric Cu(II) alkoxide complexes were prepared and fully characterized as models for intermediates in copper/radical mediated alcohol oxidation catalysis: Tp t BuR Cu II OCH 2 CF 3  with Tp t Bu  = hydro-tris(3- tert -butyl-pyrazol-1-yl)borate  1  or Tp t BuMe  = hydro-tris(3- tert -butyl-5-methyl-pyrazol-1-yl)borate  2 . These complexes were made as models for potential intermediates in enzymatic and synthetic catalytic cycles for alcohol oxidation. However, the alkoxide ligands are not readily oxidized by loss of H; instead, these complexes...

Switchover of the Mechanism between Electron Transfer and Hydrogen-Atom Transfer for a Protonated Manganese(IV)–Oxo Complex by Changing Only the Reaction Temperature

Dr. Jieun Jung, Surin Kim, Dr. Yong-Min Lee, Prof. Dr. Wonwoo Nam , Prof. Dr. Shunichi Fukuzumi First published:  18 May 2016 Full publication history DOI:  10.1002/anie.201602460 View/save citation Cited by:  0  articles   Check for new citations Abstract Hydroxylation of mesitylene by a nonheme manganese(IV)–oxo complex, [(N4Py)Mn IV (O)] 2+  ( 1 ), proceeds via one-step hydrogen-atom transfer (HAT) with a large deuterium kinetic isotope effect (KIE) of 3.2(3) at 293 K. In contrast, the same reaction with a triflic acid-bound manganese(IV)-oxo complex, [(N4Py)Mn IV (O)] 2+ -(HOTf) 2  ( 2 ), proceeds via electron transfer (ET) with no KIE at 293 K. Interestingly, when the reaction temperature is lowered to less than 263 K in the reaction of  2 , however, the mechanism changes again from ET to HAT with a large KIE of 2.9(3). Such a switchover of the reaction mechanism ...

A Purple Cupredoxin from Nitrosopumilus maritimus Containing a Mononuclear Type 1 Copper Center with an Open Binding Site

Parisa Hosseinzadeh † , Shiliang Tian ‡ , Nicholas M. Marshall ‡ , James Hemp † , Timothy Mullen ‡ , Mark J. Nilges ⊥ , Yi-Gui Gao ∇ , Howard Robinson ∥ , David A. Stahl # , Robert B. Gennis * † ‡ , and Yi Lu * † ‡ † Department of Biochemistry, ‡ Department of Chemistry, ∇ Biocrystallization Facility, and ⊥ EPR Center, University of Illinois at Urbana−Champaign , Urbana, Illinois 61801, United States ∥ Biology Department, Brookhaven National Laboratory , Upton, New York 11973-5000, United States # Department of Civil and Environmental Engineering, University of Washington , Seattle, Washington 98195, United States J. Am. Chem. Soc. , Article ASAP DOI: 10.1021/jacs.5b13128 Publication Date (Web): April 27, 2016 Copyright © 2016 American Chemical Society http://pubs.acs.org/doi/abs/10.1021/jacs.5b13128   http://pubs.acs.org/doi/pdf/10.1021/jacs.5b13128   Abstract Mononuclear cupredoxin proteins usually contain a coordinately saturated type 1 copp...