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Lee H, Yun J. Copper(I)-Catalyzed Enantioselective 1,6-Borylation of α,β,γ,δ-Unsaturated Phosphonates. Org Lett 2018; 20:7961-7964. [DOI: 10.1021/acs.orglett.8b03532] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Hyesu Lee
- Department of Chemistry and Institute of Basic Science, Sungkyunkwan University, Suwon 16419, Korea
| | - Jaesook Yun
- Department of Chemistry and Institute of Basic Science, Sungkyunkwan University, Suwon 16419, Korea
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Boucher G, Said B, Ostler E, Resmini M, Brocklehurst K, Gallacher G. Evidence that the mechanism of antibody-catalysed hydrolysis of arylcarbamates can be determined by the structure of the immunogen used to elicit the catalytic antibody. Biochem J 2007; 401:721-6. [PMID: 17020536 PMCID: PMC1770849 DOI: 10.1042/bj20060551] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Revised: 08/22/2006] [Accepted: 10/04/2006] [Indexed: 11/17/2022]
Abstract
A kinetically homogeneous anti-phosphate catalytic antibody preparation was shown to catalyse the hydrolysis of a series of O-aryl N-methyl carbamates containing various substituents in the 4-position of the O-phenyl group. The specific nature of the antibody catalysis was demonstrated by the adherence of these reactions to the Michaelis-Menten equation, the complete inhibition by a hapten analogue, and the failure of the antibody to catalyse the hydrolysis of the 2-nitrophenyl analogue of the 4-nitrophenylcarbamate substrate. Hammett sigma-rho analysis suggests that both the non-catalysed and antibody-catalysed reactions proceed by mechanisms in which development of the aryloxyanion of the leaving group is well advanced in the transition state of the rate-determining step. This is probably the ElcB (elimination-addition) mechanism for the non-catalysed reaction, but for the antibody-catalysed reaction might be either ElcB or B(Ac)2 (addition-elimination), in which the elimination of the aryloxy group from the tetrahedral intermediate has become rate-determining. This result provides evidence of the dominance of recognition of phenolate ion character in the phosphate hapten in the elicitation process, and is discussed in connection with data from the literature that suggest a B(Ac)2 mechanism, with rate-determining formation of the tetrahedral intermediate for the hydrolysis of carbamate substrates catalysed by an antibody elicited by a phosphonamidate hapten in which phenolate anion character is minimized. The present paper contributes to the growing awareness that small differences in the structure of haptens can produce large differences in catalytic characteristics.
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Affiliation(s)
- Guillaume Boucher
- *School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Bilal Said
- *School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Elizabeth L. Ostler
- *School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Marina Resmini
- †School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Keith Brocklehurst
- †School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Gerard Gallacher
- *School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
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Gul S, Brown R, May E, Mazzulla M, Smyth MG, Berry C, Morby A, Powell DJ. Staphylococcus aureus DNA ligase: characterization of its kinetics of catalysis and development of a high-throughput screening compatible chemiluminescent hybridization protection assay. Biochem J 2005; 383:551-9. [PMID: 15283677 PMCID: PMC1133749 DOI: 10.1042/bj20040054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
DNA ligases are key enzymes involved in the repair and replication of DNA. Prokaryotic DNA ligases uniquely use NAD+ as the adenylate donor during catalysis, whereas eukaryotic enzymes use ATP. This difference in substrate specificity makes the bacterial enzymes potential targets for therapeutic intervention. We have developed a homogeneous chemiluminescence-based hybridization protection assay for Staphylococcus aureus DNA ligase that uses novel acridinium ester technology and demonstrate that it is an alternative to the commonly used radiometric assays for ligases. The assay has been used to determine a number of kinetic constants for S. aureus DNA ligase catalysis. These included the K(m) values for NAD+ (2.75+/-0.1 microM) and the acridinium-ester-labelled DNA substrate (2.5+/-0.2 nM). A study of the pH-dependencies of kcat, K(m) and kcat/K(m) has revealed values of kinetically influential ionizations within the enzyme-substrate complexes (kcat) and free enzyme (kcat/K(m)). In each case, the curves were shown to be composed of one kinetically influential ionization, for k(cat), pK(a)=6.6+/-0.1 and kcat/K(m), pK(a)=7.1+/-0.1. Inhibition characteristics of the enzyme against two Escherichia coli DNA ligase inhibitors have also been determined with IC50 values for these being 3.30+/-0.86 microM for doxorubicin and 1.40+/-0.07 microM for chloroquine diphosphate. The assay has also been successfully miniaturized to a sufficiently low volume to allow it to be utilized in a high-throughput screen (384-well format; 20 microl reaction volume), enabling the assay to be used in screening campaigns against libraries of compounds to discover leads for further drug development.
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Affiliation(s)
- Sheraz Gul
- Assay Development and Compound Profiling, GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park (North), Third Avenue, Harlow, Essex CM19 4AW, UK.
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Sonkaria S, Boucher G, FLóREZ-ÁLVAREZ J, Said B, Hussain S, Ostler E, Gul S, Thomas E, Resmini M, Gallacher G, Brocklehurst K. Evidence for 'lock and key' character in an anti-phosphonate hydrolytic antibody catalytic site augmented by non-reaction centre recognition: variation in substrate selectivity between an anti-phosphonate antibody, an anti-phosphate antibody and two hydrolytic enzymes. Biochem J 2004; 381:125-30. [PMID: 15053743 PMCID: PMC1133769 DOI: 10.1042/bj20031966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Revised: 02/11/2004] [Accepted: 03/31/2004] [Indexed: 11/17/2022]
Abstract
The substrate selectivities of an anti-phosphonate and an anti-phosphate kinetically homogeneous polyclonal catalytic antibody preparation and two hydrolytic enzymes were compared by using hapten-analogous and truncated carbonate and ester substrates each containing a 4-nitrophenolate leaving group. Syntheses of the truncated substrates devoid of recognition features in the non-leaving group parts of the substrates are reported. The relatively high kinetic selectivity of the more active anti-phosphonate antibody preparation is considered to depend on a relatively rigid catalytic site with substantial reaction centre specificity together with other important recognition interactions with the extended non-leaving group part of the substrate. In contrast, the less catalytically active, more flexible anti-phosphate antibody exhibits much lower kinetic selectivity for the substrate reaction centre comparable with that of the hydrolytic enzymes with activity much less dependent on recognition interactions with the non-leaving group part of the substrate. The ways in which haptenic flexibility and IgG architecture might contribute to the differential kinetic selectivities are indicated.
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Affiliation(s)
- Sanjiv Sonkaria
- *Laboratory of Structural and Mechanistic Enzymology, School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Guillaume Boucher
- †Department of Biological Sciences, School of Pharmacy and Biomolecular Sciences, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - José FLóREZ-ÁLVAREZ
- *Laboratory of Structural and Mechanistic Enzymology, School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Bilal Said
- †Department of Biological Sciences, School of Pharmacy and Biomolecular Sciences, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Syeed Hussain
- *Laboratory of Structural and Mechanistic Enzymology, School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Elizabeth L. Ostler
- †Department of Biological Sciences, School of Pharmacy and Biomolecular Sciences, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Sheraz Gul
- *Laboratory of Structural and Mechanistic Enzymology, School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
| | - Emrys W. Thomas
- ‡Department of Biological Sciences, University of Salford, The Crescent, Salford M5 4JW, U.K
| | - Marina Resmini
- §Department of Chemistry, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
- To whom correspondence should be addressed (e-mail or )
| | - Gerard Gallacher
- †Department of Biological Sciences, School of Pharmacy and Biomolecular Sciences, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, U.K
| | - Keith Brocklehurst
- *Laboratory of Structural and Mechanistic Enzymology, School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K
- To whom correspondence should be addressed (e-mail or )
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