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Kijek TM, Bozue JA, Panchal RG, Litosh VA, Woodard RW, Ahmed SA. A direct spectropolarimetric assay of arabinose 5-phosphate isomerase. Anal Biochem 2021; 622:114116. [PMID: 33716126 DOI: 10.1016/j.ab.2021.114116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/20/2020] [Accepted: 01/18/2021] [Indexed: 10/21/2022]
Abstract
Arabinose 5-phosphate isomerase (API) catalyzes the reversible isomerization of Ribulose 5-phosphate (Ru5P) to Arabinose 5-Phosphate (Ar5P) for the production of 3-deoxy-2-octulosonic acid 8-phosphate (KDO), a component of bacterial lipopolysaccharide (LPS) of gram-negative bacteria. API is an attractive target for therapeutic development against gram-negative bacterial pathogens. The current assay method of API activity utilizes a general reaction for keto sugar determination in a secondary, 3-h color development reaction with 25 N sulfuric acid which poses hazard to both personnel and instrumentation. We therefore aimed to develop a more user friendly assay of the enzyme. Since Ru5P absorbs in the UV region and contains at least 2 chiral centers, it can be expected to display circular dichroism (CD). A wavelength scan revealed indeed Ru5P displays a pronounced negative ellipticity of 30,560 mDeg M-1cm-1 at 279 nm in Tris buffer pH 9.1 but Ar5P does not have any CD. API enzymatic reactions were monitored directly and continuously in real time by following the disappearance of CD from the Ru5P substrate, or by the appearance of CD from Ar5P substrate. The CD signal at this wavelength was not affected by absorption of the enzyme protein or of small molecules, or turbidity of the solution. Common additives in protein and enzyme reaction mixtures such as detergents, metals, and 5% dimethylsulfoxide did not interfere with the CD signal. Assay reactions of 1-3 min consistently yielded reproducible results. Introduction of accessories in a spectropolarimeter will easily adapt this assay to high throughput format for screening thousands of small molecules as inhibitor candidates of API.
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Affiliation(s)
- Todd M Kijek
- Systems and Structural Biology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, 21702, USA
| | - Joel A Bozue
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, 21702, USA
| | - Rekha G Panchal
- Systems and Structural Biology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, 21702, USA
| | - Vladislav A Litosh
- Medical Countermeasures Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, 21702, USA
| | - Ronald W Woodard
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1065, USA
| | - S Ashraf Ahmed
- Systems and Structural Biology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, 21702, USA.
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Synchrotron-Radiation Vacuum-Ultraviolet Circular-Dichroism Spectroscopy for Characterizing the Structure of Saccharides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 30484246 DOI: 10.1007/978-981-13-2158-0_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Circular-dichroism (CD) spectroscopy is a powerful tool for analyzing the structures of chiral molecules and biomolecules. The development of CD instruments using synchrotron radiation has greatly expanded the utility of this method by extending the spectra to the vacuum-ultraviolet (VUV) region below 190 nm and thereby yielding information that is unobtainable by conventional CD instruments. This technique is especially advantageous for monitoring the structure of saccharides that contain hydroxy and acetal groups with high-energy transitions in the VUV region. Combining VUVCD spectra with theoretical calculations provides new insight into the contributions of anomeric hydroxy groups and rotational isomers of hydroxymethyl groups to the dynamics, intramolecular hydrogen bonds, and hydration of saccharides in aqueous solution.
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Tapping into Synchrotron and Benchtop Circular Dichroism Spectroscopy for Expanding Studies of Complex Polysaccharides and their Interactions in Anoxic Archaeological Wood. HERITAGE 2019. [DOI: 10.3390/heritage2010009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Circular dichroism (CD) (and synchrotron circular dichroism (SCD)) spectroscopy is a rapid, highly sensitive technique used to investigate structural conformational changes in biomolecules in response to interactions with ligands in solution and in film. It is a chiroptical method and at least one of the interacting molecules must possess optical activity (or chirality). In this review, we compare the capabilities of CD and SCD in the characterisation of celluloses and lignin polymers in archaeological wood. Cellulose produces a range of spectral characteristics dependent on environment and form; many of the reported transitions occur in the vacuum-ultraviolet region (< 180 nm) most conveniently delivered using a synchrotron source. The use of induced CD in which achiral dyes are bound to celluloses to give shifted spectra in the visible region is also discussed, together with its employment to identify the handedness of the chiral twists in nanocrystalline cellulose. Lignin is one target for the design of future consolidants that interact with archaeological wood to preserve it. It is reportedly achiral, but here we review several studies in which CD spectroscopy has successfully revealed lignin interactions with chiral enzymes, highlighting the potential usefulness of the technique in future research to identify new generation consolidants.
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Alkattan M, Prunet J, Shaver MP. Functionalizable Stereocontrolled Cyclopolyethers by Ring-Closing Metathesis as Natural Polymer Mimics. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Mohammed Alkattan
- EaStCHEM; School of Chemistry; University of Edinburgh; Joseph Black Building; David Brewster Road Edinburgh EH9 3FJ UK
- WestCHEM; School of Chemistry; University of Glasgow; Joseph Black Building; University Avenue Glasgow G12 8QQ UK
| | - Joëlle Prunet
- WestCHEM; School of Chemistry; University of Glasgow; Joseph Black Building; University Avenue Glasgow G12 8QQ UK
| | - Michael P. Shaver
- EaStCHEM; School of Chemistry; University of Edinburgh; Joseph Black Building; David Brewster Road Edinburgh EH9 3FJ UK
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Alkattan M, Prunet J, Shaver MP. Functionalizable Stereocontrolled Cyclopolyethers by Ring-Closing Metathesis as Natural Polymer Mimics. Angew Chem Int Ed Engl 2018; 57:12835-12839. [PMID: 29873428 PMCID: PMC6175094 DOI: 10.1002/anie.201805113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Indexed: 11/24/2022]
Abstract
Whereas complex stereoregular cyclic architectures are commonplace in biomacromolecules, they remain rare in synthetic polymer chemistry, thus limiting the potential to develop synthetic mimics or advanced materials for biomedical applications. Herein we disclose the formation of a stereocontrolled 1,4‐linked six‐membered cyclopolyether prepared by ring‐closing metathesis (RCM). Ru‐mediated RCM, with careful control of the catalyst, concentration, and temperature, selectively affords the six‐membered‐ring cyclopolymer. Under optimized reaction conditions, no metathetical degradation, macrocycle formation, or cross‐linking was observed. Post‐polymerization modification by dihydroxylation afforded a novel polymer family encompassing a poly(ethylene glycol) backbone and sugar‐like functionalities (“PEGose”). This strategy also paves the way for using RCM as an efficient method to synthesize other stereocontrolled cyclopolymers.
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Affiliation(s)
- Mohammed Alkattan
- EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK.,WestCHEM, School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Joëlle Prunet
- WestCHEM, School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow, G12 8QQ, UK
| | - Michael P Shaver
- EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK
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Matsuo K, Gekko K. Vacuum-ultraviolet circular dichroism study of saccharides by synchrotron radiation spectrophotometry. Carbohydr Res 2004; 339:591-7. [PMID: 15013395 DOI: 10.1016/j.carres.2003.11.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Accepted: 11/03/2003] [Indexed: 10/26/2022]
Abstract
Vacuum-ultraviolet circular dichroism (VUVCD) spectra of five monosaccharides (D-glucose, D-mannose, D-galactose, D-xylose, and D-lyxose) and five disaccharides (maltose, isomaltose, cellobiose, gentiobiose, and lactose) were measured to 160 nm using a synchrotron-radiation VUVCD spectrophotometer in aqueous solution under high vacuum at 25 degrees C. Most of the saccharides show a positive peak with some shoulders at around 170 nm, except for D-galactose and lactose, which show two distinct negative peaks at around 165 and 177 nm. These spectra are influenced by such structural factors as alpha and beta anomers at C-1, axial and equatorial hydroxyl groups at C-2 and C-4, trans (T) and gauche (G) conformations of the hydroxymethyl group at C-5, and the type of glycosidic linkage. Deconvolution of the VUVCD spectra of D-glucose, D-mannose, and D-galactose into six independent Gaussian components for alpha-GG, alpha-GT, alpha-TG, beta-GG, beta-GT, and beta-TG conformations suggests that the alpha anomer has red-shifted spectra relative to the beta anomer, and that GG and GT conformations have positive and negative circular dichroism signs, respectively, while the sign for TG conformation is anomer dependent. These speculations from the deconvolution analyses are also supported by the VUVCD spectra of disaccharides. These results give new insight into the equilibrium conformations of saccharides, demonstrating the usefulness of synchrotron-radiation VUVCD spectroscopy.
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Affiliation(s)
- Koichi Matsuo
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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Engle AR, Purdie N, Hyatt JA. Induced circular dichroism study of the aqueous solution complexation of cello-oligosaccharides and related polysaccharides with aromatic dyes. Carbohydr Res 1994; 265:181-95. [PMID: 7842441 DOI: 10.1016/0008-6215(94)00235-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Acetobacter xylinum, grown in the presence of low levels of the water-soluble dye Calcofluor White ST produces a pellicle of cellulose that has no detectable crystallinity. Biological factors of this sort are probably more important than physical factors in controlling the higher order structures of celluloses. Circular dichroism (CD) is induced by complexes that are formed by specific interactions between chiral oligosaccharides and dye molecules. Using CD, equilibrium constants were measured for the association reactions between various dyes with a series of cello-oligosaccharides (n = 2-6), methylcellulose, hydroxypropylcellulose (HPC), amylose, cyclomalto-oligosaccharides (cyclodextrins), and the linear malto-oligosaccharides (n = 3-7). Possible structural features of the complexes are discussed. Dyes that are capable of binding to the higher cello-oligomers in aqueous solutions are the same dyes that modify the solid structure of bacterial cellulose. An analogy between the binding of water-soluble dyes to cello-oligosaccharides and the binding of the cellulose-degrading enzyme, cellobiohydrolase I, to cellulose is discussed.
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Affiliation(s)
- A R Engle
- Chemistry Department, Oklahoma State University, Stillwater 74078-0447
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Barron LD, Gargaro AR, Wen ZQ, MacNicol DD, Butters C. Vibrational Raman optical activity of cyclodextrins. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0957-4166(00)80537-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bertucci C, Salvadori P, Zullino G, Pini D, Johnson WC. Circular dichroism spectra of some model compounds related to D-glucopyranose and D-galactopyranose. Carbohydr Res 1986; 149:299-307. [PMID: 3756947 DOI: 10.1016/s0008-6215(00)90053-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
C.d. spectra have been measured in aqueous solution to 168 nm for some model compounds related to D-glucopyranose and D-galactopyranose. C.d. difference-spectra reveal the contribution of certain functional groups and confirm contributions for other groups found in earlier work.
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Morris ER, Stevens ES, Frangou SA, Rees DA. Total optical activity of agarose: relation to observable transitions in the vacuum ultraviolet. Biopolymers 1986; 25:959-73. [PMID: 3719083 DOI: 10.1002/bip.360250514] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Sathyanarayana BK, Stevens ES, Texter J. Random-phase calculation of the low-energy circular dichroism in glucans. Biopolymers 1985; 24:1365-83. [PMID: 4027347 DOI: 10.1002/bip.360240719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Sathyanarayana BK, Stevens ES. Theoretical study of the conformations of pustulan [(1----6)-beta-D-glucan]. J Biomol Struct Dyn 1983; 1:947-59. [PMID: 6400907 DOI: 10.1080/07391102.1983.10507496] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The total potential energy including nonbonded, torsional and hydrogen bond contributions has been computed for pustulan, a (1----6) linked beta-D-glucan polysaccharide, as a function of rotational angles phi, psi, and omega. The (phi,psi,omega)-space contains many local minima and at least three distinct deep minima. Two minima at (phi,psi,omega) = (25 degrees, 190 degrees,gg) and (phi,psi,omega) = 65 degrees, 150 degrees,gg) of almost equal energies have helical parameters (n = 5.2, h = 1.0A) and (n = 3.2, h = 1.5A), respectively. A third minimum at (phi,psi,omega) = (40 degrees, 70 degrees gt) leads to an extended zig-zag structure (n = 2.2, h = 2.2A). Energy maps obtained for gentiobiose, the disaccharide of pustulan, also reveal many local minima and the small energy differences among them indicate that gentiobiose is extremely flexible. Gentiodextrins, a family of cyclic molecules of (1----6)-beta-D-glucose residues, were also studied. Conformations free from steric hindrance were found for cyclic molecules with three to six glucose residues.
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Herschlag D, Stevens ES, Gander JE. Galactofuranosyl-containing glycopeptide of Penicillium charlesii. Vacuum ultraviolet circular dichroism. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1983; 22:16-20. [PMID: 6224750 DOI: 10.1111/j.1399-3011.1983.tb02063.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The far and vacuum u.v. circular dichroism (CD) of peptidophosphogalactomannan from P. charlesii is reported to 182.5 nm in aqueous and aqueous/organic solvents, and to 150nm in films. CD of films of the peptide-free derivative is reported to 150 nm. On the basis of these data we conclude that the peptide chain is unordered, and may best be described as a hydrated coil showing some stiffness. The small observed saccharide CD may result from cancellation of contributions from the various saccharide structures present or from a lack of repeating secondary structure.
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Bulpin PV, Welsh EJ, Morris ER. Physical Characterization of Amylose-Fatty Acid Complexes in Starch Granules and in Solution. STARCH-STARKE 1982. [DOI: 10.1002/star.19820341004] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Thom D, Grant GT, Morris ER, Rees DA. Characterisation of cation binding and gelation of polyuronates by circular dichroism. Carbohydr Res 1982. [DOI: 10.1016/s0008-6215(00)81023-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Saitô H, Tabeta R. 13C CHEMICAL SHIFTS OF SOLID (1→4)-α-D-GLUCANS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING (CP/MAS) NMR SPECTROSCOPY. CONFORMATION-DEPENDENT13C CHEMICAL SHIFT AS A REFERENCE IN DETERMINING CONFORMATION IN AQUEOUS SOLUTION. CHEM LETT 1981. [DOI: 10.1246/cl.1981.713] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Frangou S, Morris E, Rees D, Welsh E. A combined c.d. and o.r.d. approach to carbohydrate chain conformation: the amylose—iodine complex. Int J Biol Macromol 1980. [DOI: 10.1016/0141-8130(80)90071-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Texter J, Stevens ES. Random‐phase circular dichroism calculations of the σ/3s←n transition in chiral alcohols. J Chem Phys 1979. [DOI: 10.1063/1.437582] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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