1
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Paparella A, Cahill SM, Aboulache BL, Schramm VL. Clostridioides difficile TcdB Toxin Glucosylates Rho GTPase by an S Ni Mechanism and Ion Pair Transition State. ACS Chem Biol 2022; 17:2507-2518. [PMID: 36038138 PMCID: PMC9486934 DOI: 10.1021/acschembio.2c00408] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Toxins TcdA and TcdB from Clostridioides difficile glucosylate human colon Rho GTPases. TcdA and TcdB glucosylation of RhoGTPases results in cytoskeletal changes, causing cell rounding and loss of intestinal integrity. Clostridial toxins TcdA and TcdB are proposed to catalyze glucosylation of Rho GTPases with retention of stereochemistry from UDP-glucose. We used kinetic isotope effects to analyze the mechanisms and transition-state structures of the glucohydrolase and glucosyltransferase activities of TcdB. TcdB catalyzes Rho GTPase glucosylation with retention of stereochemistry, while hydrolysis of UDP-glucose by TcdB causes inversion of stereochemistry. Kinetic analysis revealed TcdB glucosylation via the formation of a ternary complex with no intermediate, supporting an SNi mechanism with nucleophilic attack and leaving group departure occurring on the same face of the glucose ring. Kinetic isotope effects combined with quantum mechanical calculations revealed that the transition states of both glucohydrolase and glucosyltransferase activities of TcdB are highly dissociative. Specifically, the TcdB glucosyltransferase reaction proceeds via an SNi mechanism with the formation of a distinct oxocarbenium phosphate ion pair transition state where the glycosidic bond to the UDP leaving group breaks prior to attack of the threonine nucleophile from Rho GTPase.
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2
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Takeuchi H, Fujimori Y, Ueda Y, Shibayama H, Nagaishi M, Yoshimura T, Sasamori T, Tokitoh N, Furuta T, Kawabata T. Solvent-Dependent Mechanism and Stereochemistry of Mitsunobu Glycosylation with Unprotected Pyranoses. Org Lett 2020; 22:4754-4759. [DOI: 10.1021/acs.orglett.0c01549] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hironori Takeuchi
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Yusuke Fujimori
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Yoshihiro Ueda
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Hiromitsu Shibayama
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Masaru Nagaishi
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Tomoyuki Yoshimura
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Takahiro Sasamori
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Norihiro Tokitoh
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Takumi Furuta
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Takeo Kawabata
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
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3
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Zhuo MH, Wilbur DJ, Kwan EE, Bennett CS. Matching Glycosyl Donor Reactivity to Sulfonate Leaving Group Ability Permits S N2 Glycosylations. J Am Chem Soc 2019; 141:16743-16754. [PMID: 31550879 PMCID: PMC6814073 DOI: 10.1021/jacs.9b07022] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Here we demonstrate that highly β-selective glycosylation reactions can be achieved when the electronics of a sulfonyl chloride activator and the reactivity of a glycosyl donor hemiacetal are matched. While these reactions are compatible with the acid- and base-sensitive protecting groups that are commonly used in oligosaccharide synthesis, these protecting groups are not relied upon to control selectivity. Instead, β-selectivity arises from the stereoinversion of an α-glycosyl arylsulfonate in an SN2-like mechanism. Our mechanistic proposal is supported by NMR studies, kinetic isotope effect (KIE) measurements, and DFT calculations.
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Affiliation(s)
- Ming-Hua Zhuo
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , Massachusetts 02155 , United States
| | - David J Wilbur
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , Massachusetts 02155 , United States
| | - Eugene E Kwan
- Merck & Co. Inc. , 33 Avenue Louis Pasteur , Boston , Massachusetts 02115 , United States
| | - Clay S Bennett
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , Massachusetts 02155 , United States
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4
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Glancy JH, Lee DM, Read EO, Williams IH. Computational simulation of mechanism and isotope effects on acetal heterolysis as a model for glycoside hydrolysis. PURE APPL CHEM 2019. [DOI: 10.1515/pac-2019-0221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Abstract
DFT calculations for the equilibrium isotope effect for deuterium substitution at the anomeric centre Cα in 2-(p-nitrophenoxy)tetrahydropyran with continuum solvation show significant variation in the range of relative permittivity 2 ≤ ε ≤ 10. One-dimensional scans of potential energy (with implicit solvation by water) or of free energy (from QM/MM potentials of mean force with explicit aqueous solvation with a hybrid AM1/OPLS method) for heterolysis of the bond between Cα and the nucleofuge do not show a transition state. A two-dimensional free-energy surface that considers also the distance between Cα and a nucleophilic water indicates a pre-association DN*ANint
‡ mechanism with a transition state involving nucleophilic attack upon an ion-pair intermediate, and this is supported by good agreement between the mean values of the calculated and experimental α-D KIEs. However, the magnitudes of the standard deviations about the mean values for the making and breaking C–O bonds suggest that the transition state is rather plastic, with Cα–Onu≈2 ± 0.4 Å and Cα–Olg≈3 ± 0.5 Å. Not only is nucleophilic solvent assistance necessary, but there is also evidence for electrophilic assistance through specific hydrogen bonding to the nucleofuge.
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Affiliation(s)
- John H. Glancy
- Department of Chemistry , University of Bath , Bath BA2 7AY , UK
| | - Daniel M. Lee
- Department of Chemistry , University of Bath , Bath BA2 7AY , UK
| | - Emily O. Read
- Department of Chemistry , University of Bath , Bath BA2 7AY , UK
| | - Ian H. Williams
- Department of Chemistry , University of Bath , Bath BA2 7AY , UK
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5
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Gama SR, Lo BSY, Séguin J, Pallitsch K, Hammerschmidt F, Zechel DL. C-H Bond Cleavage Is Rate-Limiting for Oxidative C-P Bond Cleavage by the Mixed Valence Diiron-Dependent Oxygenase PhnZ. Biochemistry 2019; 58:5271-5280. [PMID: 31046250 DOI: 10.1021/acs.biochem.9b00145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PhnZ utilizes a mixed valence diiron(II/III) cofactor and O2 to oxidatively cleave the carbon-phosphorus bond of (R)-2-amino-1-hydroxyethylphosphonic acid to form glycine and orthophosphate. The active site residues Y24 and E27 are proposed to mediate induced-fit recognition of the substrate and access of O2 to one of the active site Fe ions. H62 is proposed to deprotonate the C1-hydroxyl of the substrate during catalysis. Kinetic isotope effects (KIEs), pH-rate dependence, and site-directed mutagenesis were used to probe the rate-determining transition state and the roles of these three active site residues. Primary deuterium KIE values of 5.5 ± 0.3 for D(V) and 2.2 ± 0.4 for D(V/K) were measured with (R)-2-amino[1-2H1]-1-hydroxyethylphosphonic acid, indicating that cleavage of the C1-H bond of the substrate is rate-limiting. This step is also rate-limiting for PhnZ Y24F, as shown by a significant deuterium KIE value of 2.3 ± 0.1 for D(V). In contrast, a different reaction step appears to be rate-limiting for the PhnZ E27A and H62A variants, which exhibited D(V) values near unity. A solvent KIE of 2.2 ± 0.3 for D2O(V) is observed for PhnZ. Significant solvent KIE values are also observed for the PhnZ Y24F and E27A variants. In contrast, the PhnZ H62A variant does not show a significant solvent KIE, suggesting that H62 is mediating proton transfer in the transition state. A proton inventory study with PhnZ indicates that 1.5 ± 0.6 protons are in flight in the rate-determining step. Overall, the rate-determining transition state for oxidative C-P bond cleavage by PhnZ is proposed to involve C-H bond cleavage that is coupled to deprotonation of the substrate C1-hydroxyl by H62.
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Affiliation(s)
- Simanga R Gama
- Department of Chemistry , Queen's University , Kingston , Ontario , Canada K7L 3N6
| | - Becky Suet Yan Lo
- Department of Chemistry , Queen's University , Kingston , Ontario , Canada K7L 3N6
| | - Jacqueline Séguin
- Department of Chemistry , Queen's University , Kingston , Ontario , Canada K7L 3N6
| | - Katharina Pallitsch
- Institute of Organic Chemistry , University of Vienna , 1090 Vienna , Austria
| | | | - David L Zechel
- Department of Chemistry , Queen's University , Kingston , Ontario , Canada K7L 3N6
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6
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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7
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Adero PO, Amarasekara H, Wen P, Bohé L, Crich D. The Experimental Evidence in Support of Glycosylation Mechanisms at the S N1-S N2 Interface. Chem Rev 2018; 118:8242-8284. [PMID: 29846062 PMCID: PMC6135681 DOI: 10.1021/acs.chemrev.8b00083] [Citation(s) in RCA: 215] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A critical review of the state-of-the-art evidence in support of the mechanisms of glycosylation reactions is provided. Factors affecting the stability of putative oxocarbenium ions as intermediates at the SN1 end of the mechanistic continuum are first surveyed before the evidence, spectroscopic and indirect, for the existence of such species on the time scale of glycosylation reactions is presented. Current models for diastereoselectivity in nucleophilic attack on oxocarbenium ions are then described. Evidence in support of the intermediacy of activated covalent glycosyl donors is reviewed, before the influences of the structure of the nucleophile, of the solvent, of temperature, and of donor-acceptor hydrogen bonding on the mechanism of glycosylation reactions are surveyed. Studies on the kinetics of glycosylation reactions and the use of kinetic isotope effects for the determination of transition-state structure are presented, before computational models are finally surveyed. The review concludes with a critical appraisal of the state of the art.
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Affiliation(s)
- Philip Ouma Adero
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - Harsha Amarasekara
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - Peng Wen
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
| | - Luis Bohé
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301 , Université Paris-Sud Université Paris-Saclay , 1 avenue de la Terrasse , 91198 Gif-sur-Yvette , France
| | - David Crich
- Department of Chemistry , Wayne State University , 5101 Cass Avenue , Detroit , Michigan 48202 , United States
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8
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Gama SR, Balachandran N, Berti PJ. Campylobacter jejuni KDO8P Synthase, Its Inhibition by KDO8P Oxime, and Control of the Residence Time of Slow-Binding Inhibition. Biochemistry 2018; 57:5327-5338. [DOI: 10.1021/acs.biochem.8b00748] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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9
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Time-dependent view of an isotope effect in electron-nuclear nonequilibrium dynamics with applications to N 2. Proc Natl Acad Sci U S A 2018; 115:5890-5895. [PMID: 29784776 DOI: 10.1073/pnas.1804455115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Isotopic fractionation in the photodissociation of N2 could explain the considerable variation in the 14N/15N ratio in different regions of our galaxy. We previously proposed that such an isotope effect is due to coupling of photoexcited bound valence and Rydberg electronic states in the frequency range where there is strong state mixing. We here identify features of the role of the mass in the dynamics through a time-dependent quantum-mechanical simulation. The photoexcitation of N2 is by an ultrashort pulse so that the process has a sharply defined origin in time and so that we can monitor the isolated molecule dynamics in time. An ultrafast pulse is necessarily broad in frequency and spans several excited electronic states. Each excited molecule is therefore not in a given electronic state but in a superposition state. A short time after excitation, there is a fairly sharp onset of a mass-dependent large population transfer when wave packets on two different electronic states in the same molecule overlap. This coherent overlap of the wave packets on different electronic states in the region of strong coupling allows an effective transfer of population that is very mass dependent. The extent of the transfer depends on the product of the populations on the two different electronic states and on their relative phase. It is as if two molecules collide but the process occurs within one molecule, a molecule that is simultaneously in both states. An analytical toy model recovers the (strong) mass and energy dependence.
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10
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Balachandran N, To F, Berti PJ. Linear Free Energy Relationship Analysis of Transition State Mimicry by 3-Deoxy-d-arabino-heptulosonate-7-phosphate (DAHP) Oxime, a DAHP Synthase Inhibitor and Phosphate Mimic. Biochemistry 2017; 56:592-601. [PMID: 28045507 DOI: 10.1021/acs.biochem.6b01211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Naresh Balachandran
- Department of Chemistry & Chemical Biology and ‡Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Frederick To
- Department of Chemistry & Chemical Biology and ‡Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Paul J. Berti
- Department of Chemistry & Chemical Biology and ‡Department of Biochemistry & Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
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11
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Namanja-Magliano HA, Stratton CF, Schramm VL. Transition State Structure and Inhibition of Rv0091, a 5'-Deoxyadenosine/5'-methylthioadenosine Nucleosidase from Mycobacterium tuberculosis. ACS Chem Biol 2016; 11:1669-76. [PMID: 27019223 DOI: 10.1021/acschembio.6b00144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a bacterial enzyme that catalyzes the hydrolysis of the N-ribosidic bond in 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH). MTAN activity has been linked to quorum sensing pathways, polyamine biosynthesis, and adenine salvage. Previously, the coding sequence of Rv0091 was annotated as a putative MTAN in Mycobacterium tuberculosis. Rv0091 was expressed in Escherichia coli, purified to homogeneity, and shown to be a homodimer, consistent with MTANs from other microorganisms. Substrate specificity for Rv0091 gave a preference for 5'-deoxyadenosine relative to MTA or SAH. Intrinsic kinetic isotope effects (KIEs) for the hydrolysis of [1'-(3)H], [1'-(14)C], [5'-(3)H2], [9-(15)N], and [7-(15)N]MTA were determined to be 1.207, 1.038, 0.998, 1.021, and 0.998, respectively. A model for the transition state structure of Rv0091 was determined by matching KIE values predicted via quantum chemical calculations to the intrinsic KIEs. The transition state shows a substantial loss of C1'-N9 bond order, well-developed oxocarbenium character of the ribosyl ring, and weak participation of the water nucleophile. Electrostatic potential surface maps for the Rv0091 transition state structure show similarity to DADMe-immucillin transition state analogues. DADMe-immucillin transition state analogues showed strong inhibition of Rv0091, with the most potent inhibitor (5'-hexylthio-DADMe-immucillinA) displaying a Ki value of 87 pM.
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Affiliation(s)
- Hilda A. Namanja-Magliano
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Christopher F. Stratton
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
| | - Vern L. Schramm
- Department
of Biochemistry, Albert Einstein College of Medicine, 1300 Morris
Park Avenue, Bronx, New York 10461, United States
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12
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Yuan H, Stratton CF, Schramm VL. Transition State Structure of RNA Depurination by Saporin L3. ACS Chem Biol 2016; 11:1383-90. [PMID: 26886255 DOI: 10.1021/acschembio.5b01069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Saporin L3 from the leaves of the common soapwort is a catalyst for hydrolytic depurination of adenine from RNA. Saporin L3 is a type 1 ribosome inactivating protein (RIP) composed only of a catalytic domain. Other RIPs have been used in immunotoxin cancer therapy, but off-target effects have limited their development. In the current study, we use transition state theory to understand the chemical mechanism and transition state structure of saporin L3. In favorable cases, transition state structures guide the design of transition state analogues as inhibitors. Kinetic isotope effects (KIEs) were determined for an A14C mutant of saporin L3. To permit KIE measurements, small stem-loop RNAs that contain an AGGG tetraloop structure were enzymatically synthesized with the single adenylate bearing specific isotopic substitutions. KIEs were measured and corrected for forward commitment to obtain intrinsic values. A model of the transition state structure for depurination of stem-loop RNA (5'-GGGAGGGCCC-3') by saporin L3 was determined by matching KIE values predicted via quantum chemical calculations to a family of intrinsic KIEs. This model indicates saporin L3 displays a late transition state with the N-ribosidic bond to the adenine nearly cleaved, and the attacking water nucleophile weakly bonded to the ribosyl anomeric carbon. The transition state retains partial ribocation character, a feature common to most N-ribosyl transferases. However, the transition state geometry for saporin L3 is distinct from ricin A-chain, the only other RIP whose transition state is known.
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Affiliation(s)
- Hongling Yuan
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Christopher F. Stratton
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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13
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Phan HD, Yokoyama T, Matsumoto Y. Direct participation of counter anion in acid hydrolysis of glycoside. Org Biomol Chem 2012; 10:7382-91. [DOI: 10.1039/c2ob25451d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Increased glycosidic bond stabilities in 4-C-hydroxymethyl linked disaccharides. Carbohydr Res 2011; 346:2394-400. [DOI: 10.1016/j.carres.2011.08.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/24/2011] [Accepted: 08/25/2011] [Indexed: 11/19/2022]
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15
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Amorim L, Marcelo F, Rousseau C, Nieto L, Jiménez‐Barbero J, Marrot J, Rauter AP, Sollogoub M, Bols M, Blériot Y. Direct Experimental Evidence for the High Chemical Reactivity of α‐ and β‐Xylopyranosides Adopting a
2,5
B
Conformation in Glycosyl Transfer. Chemistry 2011; 17:7345-56. [DOI: 10.1002/chem.201003251] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Indexed: 12/12/2022]
Affiliation(s)
- Luis Amorim
- UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR 7201), FR 2769, C181, 4 place Jussieu, 75005 Paris (France)
| | - Filipa Marcelo
- UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR 7201), FR 2769, C181, 4 place Jussieu, 75005 Paris (France)
- Carbohydrate Chemistry Group, CQB‐FCUL, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749‐016 Lisbon (Portugal)
| | - Cyril Rousseau
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Kbh Ø (Denmark)
- Present address: Université d'Artois, IUT de Béthune, UCCS Artois, UMR 8181, 1230 rue de l'Université, BP 819, 62408 Béthune cedex (France)
| | - Lidia Nieto
- Centro de Investigaciones Biológicas, CSIC, 28040 Madrid (Spain)
| | | | - Jérôme Marrot
- Institut Lavoisier, Université de Versailles‐Saint‐Quentin, UMR 8180, 78035 Versailles (France)
| | - Amélia P. Rauter
- Carbohydrate Chemistry Group, CQB‐FCUL, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, 1749‐016 Lisbon (Portugal)
| | - Matthieu Sollogoub
- UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR 7201), FR 2769, C181, 4 place Jussieu, 75005 Paris (France)
| | - Mikael Bols
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Kbh Ø (Denmark)
| | - Yves Blériot
- UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR 7201), FR 2769, C181, 4 place Jussieu, 75005 Paris (France)
- Present address: Université de Poitiers, UMR 6514, Laboratoire “Synthèse et Réactivité des Substances Naturelles”, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex (France)
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16
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Ebrahimi A, Habibi-Khorassani M, Bazzi S. The impact of protonation and deprotonation of 3-methyl-2′-deoxyadenosine on N-glycosidic bond cleavage. Phys Chem Chem Phys 2011; 13:3334-43. [DOI: 10.1039/c0cp01279c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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17
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Schwartz PA, Vetticatt MJ, Schramm VL. Transition state analysis of thymidine hydrolysis by human thymidine phosphorylase. J Am Chem Soc 2010; 132:13425-33. [PMID: 20804144 DOI: 10.1021/ja105041j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Human thymidine phosphorylase (hTP) is responsible for thymidine (dT) homeostasis, and its action promotes angiogenesis. In the absence of phosphate, hTP catalyzes a slow hydrolytic depyrimidination of dT yielding thymine and 2-deoxyribose (dRib). Its transition state was characterized using multiple kinetic isotope effect (KIE) measurements. Isotopically enriched thymidines were synthesized enzymatically from glucose or (deoxy)ribose, and intrinsic KIEs were used to interpret the transition state structure. KIEs from [1'-(14)C]-, [1-(15)N]-, [1'-(3)H]-, [2'R-(3)H]-, [2'S-(3)H]-, [4'-(3)H]-, and [5'-(3)H]dTs provided values of 1.033 ± 0.002, 1.004 ± 0.002, 1.325 ± 0.003, 1.101 ± 0.004, 1.087 ± 0.005, 1.040 ± 0.003, and 1.033 ± 0.003, respectively. Transition state analysis revealed a stepwise mechanism with a 2-deoxyribocation formed early and a higher energetic barrier for nucleophilic attack of a water molecule on the high energy intermediate. An equilibrium exists between the deoxyribocation and reactants prior to the irreversible nucleophilic attack by water. The results establish activation of the thymine leaving group without requirement for phosphate. A transition state constrained to match the intrinsic KIEs was found using density functional theory. An active site histidine (His116) is implicated as the catalytic base for activation of the water nucleophile at the rate-limiting transition state. The distance between the water nucleophile and the anomeric carbon (r(C-O)) is predicted to be 2.3 A at the transition state. The transition state model predicts that deoxyribose adopts a mild 3'-endo conformation during nucleophilic capture. These results differ from the concerted bimolecular mechanism reported for the arsenolytic reaction (Birck, M. R.; Schramm, V. L. J. Am. Chem. Soc. 2004, 126, 2447-2453).
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Affiliation(s)
- Phillip A Schwartz
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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18
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Computational studies of the role of glycopyranosyl oxacarbenium ions in glycobiology and glycochemistry. Adv Carbohydr Chem Biochem 2009; 62:83-159. [PMID: 19501705 DOI: 10.1016/s0065-2318(09)00004-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Vocadlo DJ, Davies GJ. Mechanistic insights into glycosidase chemistry. Curr Opin Chem Biol 2009; 12:539-55. [PMID: 18558099 DOI: 10.1016/j.cbpa.2008.05.010] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 05/19/2008] [Indexed: 11/16/2022]
Abstract
The enzymatic hydrolysis of the glycosidic bond continues to gain importance, reflecting the critically important roles complex glycans play in health and disease as well as the rekindled interest in enzymatic biomass conversion. Recent advances include the broadening of our understanding of enzyme reaction coordinates, through both computational and structural studies, improved understanding of enzyme inhibition through transition state mimicry and fascinating insights into mechanism yielded by physical organic chemistry approaches.
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Affiliation(s)
- David J Vocadlo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, V5A 1S6, Canada.
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Lairson LL, Henrissat B, Davies GJ, Withers SG. Glycosyltransferases: structures, functions, and mechanisms. Annu Rev Biochem 2008; 77:521-55. [PMID: 18518825 DOI: 10.1146/annurev.biochem.76.061005.092322] [Citation(s) in RCA: 1349] [Impact Index Per Article: 84.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid phosphate leaving group. Only two structural folds, GT-A and GT-B, have been identified for the nucleotide sugar-dependent enzymes, but other folds are now appearing for the soluble domains of lipid phosphosugar-dependent glycosyl transferases. Structural and kinetic studies have provided new insights. Inverting glycosyltransferases utilize a direct displacement S(N)2-like mechanism involving an enzymatic base catalyst. Leaving group departure in GT-A fold enzymes is typically facilitated via a coordinated divalent cation, whereas GT-B fold enzymes instead use positively charged side chains and/or hydroxyls and helix dipoles. The mechanism of retaining glycosyltransferases is less clear. The expected two-step double-displacement mechanism is rendered less likely by the lack of conserved architecture in the region where a catalytic nucleophile would be expected. A mechanism involving a short-lived oxocarbenium ion intermediate now seems the most likely, with the leaving phosphate serving as the base.
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Affiliation(s)
- L L Lairson
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.
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Substrate-Enzyme Interactions from Modeling and Isotope Effects. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/1-4020-5372-x_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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Ruszczycky MW, Anderson VE. Interpretation of V/K isotope effects for enzymatic reactions exhibiting multiple isotopically sensitive steps. J Theor Biol 2006; 243:328-42. [DOI: 10.1016/j.jtbi.2006.06.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 06/16/2006] [Accepted: 06/19/2006] [Indexed: 11/30/2022]
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Brecker L, Kögl MF, Tyl CE, Kratzer R, Nidetzky B. NMR study of 13C-kinetic isotope effects at 13C natural abundance to characterize oxidations and an enzyme-catalyzed reduction. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.03.194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mechanisms for nucleophilic aliphatic substitution at glycosides. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2006. [DOI: 10.1016/s0065-3160(06)41005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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Young JEP, Horenstein NA. Synthesis of endo-(3-azabicyclo[3.1.0]hex-6-yl)-methanol and derivatives as new geometric/charge mimics of glycosyltransfer transition states. Tetrahedron Lett 2004. [DOI: 10.1016/j.tetlet.2004.10.156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Blériot Y, Vadivel SK, Herrera AJ, Greig IR, Kirby AJ, Sinaÿ P. Synthesis and acid catalyzed hydrolysis of B2,5 type conformationally constrained glucopyranosides: incorporation into a cellobiose analogue. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.06.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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