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Jung J, Habib M, Morrissette LJ, Timmons SC, Maerz T, Fields AJ. Non-enzymatic glycation reduces glucose transport in the human cartilage endplate independently of matrix porosity or proteoglycan content. JOR Spine 2024; 7:e1297. [PMID: 38222801 PMCID: PMC10782066 DOI: 10.1002/jsp2.1297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/30/2023] [Accepted: 09/11/2023] [Indexed: 01/16/2024] Open
Abstract
Background Intervertebral disc degeneration is associated with low back pain, which is a leading cause of disability. While the precise causes of disc degeneration are unknown, inadequate nutrient and metabolite transport through the cartilage endplate (CEP) may be one important factor. Prior work shows that CEP transport properties depend on the porosity of the CEP matrix, but little is known about the role of CEP characteristics that could influence transport properties independently from porosity. Here, we show that CEP transport properties depend on the extent of non-enzymatic glycation of the CEP matrix. Methods and Results Using in vitro ribosylation to induce non-enzymatic glycation and promote the formation of advanced glycation end products, we found that ribosylation reduced glucose partition coefficients in human cadaveric lumbar CEP tissues by 10.7%, on average, compared with donor- and site-matched CEP tissues that did not undergo ribosylation (p = 0.04). These reductions in glucose uptake were observed in the absence of differences in CEP porosity (p = 0.89) or in the amounts of sulfated glycosaminoglycans (sGAGs, p = 0.47) or collagen (p = 0.61). To investigate whether ribosylation altered electrostatic interactions between fixed charges on the sGAG molecules and the mobile free ions, we measured the charge density in the CEP matrix using equilibrium partitioning of a cationic contrast agent using micro-computed tomography. After contrast enhancement, mean X-ray attenuation was 11.9% lower in the CEP tissues that had undergone ribosylation (p = 0.02), implying the CEP matrix was less negatively charged. Conclusions Taken together, these findings indicate that non-enzymatic glycation negatively impacts glucose transport in the CEP independent of matrix porosity or sGAG content and that the effects may be mediated by alterations to matrix charge density.
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Affiliation(s)
- Jae‐Young Jung
- Department of Orthopaedic SurgeryUniversity of California San FranciscoSan FranciscoCaliforniaUSA
| | - Mohamed Habib
- Department of Orthopaedic SurgeryUniversity of California San FranciscoSan FranciscoCaliforniaUSA
| | - Luke J. Morrissette
- Department of Natural SciencesLawrence Technological UniversitySouthfieldMichiganUSA
| | - Shannon C. Timmons
- Department of Natural SciencesLawrence Technological UniversitySouthfieldMichiganUSA
| | - Tristan Maerz
- Departments of Orthopaedic Surgery and Biomedical EngineeringUniversity of MichiganAnn ArborMichiganUSA
| | - Aaron J. Fields
- Department of Orthopaedic SurgeryUniversity of California San FranciscoSan FranciscoCaliforniaUSA
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2
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Large DN, Van Doorn NA, Timmons SC. Cancer and chemicals: A research-inspired laboratory exercise based on the Ames test for mutagenicity. Biochem Mol Biol Educ 2023; 51:103-113. [PMID: 36098335 DOI: 10.1002/bmb.21674] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 05/26/2022] [Accepted: 08/19/2022] [Indexed: 06/15/2023]
Abstract
Laboratory courses should cultivate enthusiasm for research and an appreciation for real-world scientific challenges to retain undergraduate students and encourage them to pursue STEM-related careers. Course-based undergraduate research experiences (CURE) have emerged as an inclusive pedagogical model that facilitates laboratory skill development, while also improving self-efficacy and critical thinking skills. Herein, an innovative research-inspired Ames test for mutagenicity project is described. Students choose their own project theme and investigate substances using both TA98 and TA100 strains of Salmonella typhimurium to evaluate the potential for frameshift mutations and base-pair substitutions, respectively. An appropriate test concentration of each substance is first determined via a cytotoxicity assay, providing an additional learning opportunity. Students also study the mutagenicity of test substance metabolites using commercially available rat liver extracts to simulate metabolism. Overall, these experiences provide a comprehensive research project with high relevancy to human health and real-world importance. This laboratory module was assessed using CURE pre- and post-course surveys to evaluate learning gains and benefits. Assessment data illustrated that students appreciated the discovery aspect of the research project and gained skills related to reading scientific literature and effective poster presentations. Student-reported benefits of research project participation included learning new laboratory techniques, enhanced scientific writing skills, an increased tolerance for and understanding of common research challenges, and the confidence to tackle more complex research endeavors. Narrative feedback from students was very positive, with project highlights being the opportunity to select their own test substances and create new knowledge, as well as the analysis of results.
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Affiliation(s)
- Delaney N Large
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, USA
| | - Nathaniel A Van Doorn
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, USA
| | - Shannon C Timmons
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, USA
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3
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Roberts AH, Bowen JE, Zhou X, Burke I, Wenaas MH, Blake TA, Timmons SC, Kuzmanov A. Synthesis and reproductive toxicity of bisphenol A analogs with cyclic side chains in Caenorhabditis elegans. Toxicol Ind Health 2022; 38:665-674. [PMID: 36062628 DOI: 10.1177/07482337221117357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Accumulating evidence has shown that bisphenol A (BPA) affects not only the growth and development of reproductive tissues but also disrupts meiosis. Meiotic disturbances lead to the formation of aneuploid gametes, resulting in the inability to conceive, pregnancy loss, and developmental disabilities in offspring. In recent years, increasing health concerns led manufacturers to seek BPA alternatives. In response, BPA analogs have been prepared and investigated in a variety of toxicity-related studies. Despite hopes that these analogs would prove less harmful than BPA, published data show that these alternatives continue to pose a significant risk to human health. In this study, we synthesized two less investigated BPA analogs with cyclic side chains, bisphenol Y (BPY) and bisphenol Z (BPZ), and evaluated their reprotoxic potential using Caenorhabditis elegans. C. elegans were cultured on nematode growth medium plates containing a 1 mM concentration of the dimethyl sulfoxide-dissolved bisphenols. The uptake of the chemicals was via two major routes: ingestion and cuticle diffusion. Following exposure, we evaluated fertilized egg count, germline apoptosis, and embryonic lethality-three parameters previously shown to reliably predict the reprotoxic potential of bisphenols in mammals. Our results indicated that both BPY and BPZ had a significant impact on fertility, resulting in increased germline apoptosis and a reduced number of progeny, without affecting the embryonic viability. After comparison with commercially relevant BPA and bisphenol S, our findings imply that BPA analogs with cyclic side chains, BPY and BPZ, adversely affect meiotic fidelity, resulting in diminished reproductive capacity.
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Affiliation(s)
- Andrew H Roberts
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - John E Bowen
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Xinrui Zhou
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Isabella Burke
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Maxwell H Wenaas
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Timothy A Blake
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Shannon C Timmons
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
| | - Aleksandra Kuzmanov
- Department of Natural Sciences, 7431Lawrence Technological University, Southfield, MI, USA
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4
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Roberts AH, Bowen J, Zhou X, Timmons SC, Kuzmanov A. Effect of bisphenol Z and its analogs on reproductive health of
C. elegans. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.07622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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5
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Newton MD, Hartner SE, Gawronski K, Davenport EJ, Timmons SC, Baker KC, Maerz T. Nondestructive, indirect assessment of the biomechanical properties of the rat intervertebral disc using contrast-enhanced μCT. J Orthop Res 2018; 36:2030-2038. [PMID: 29314237 DOI: 10.1002/jor.23850] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 12/24/2017] [Indexed: 02/04/2023]
Abstract
Mechanical characterization of the intervertebral disc involves labor-intensive and destructive experimental methodology. Contrast-enhanced micro-computed tomography is a nondestructive imaging modality for high-resolution visualization and glycosaminoglycan quantification of cartilaginous tissues. The purpose of this study was to determine whether anionic and cationic contrast-enhanced micro-computed tomography of the intervertebral disc can be used to indirectly assess disc mechanical properties in an ex vivo model of disc degeneration. L3/L4 motion segments were dissected from female Lewis rats. To deplete glycosaminoglycan, samples were treated with 0 U/ml (Control) or 5 U/ml papain. Contrast-enhanced micro-computed tomography was performed following incubation in 40% Hexabrix (anionic) or 30 mg I/ml CA4+ (cationic) for 24 h (n = 10/contrast agent/digestion group). Motion segments underwent cyclic mechanical testing to determine compressive and tensile modulus, stiffness, and hysteresis. Glycosaminoglycan content was determined using the dimethylmethylene blue assay. Correlations between glycosaminoglycan content, contrast-enhanced micro-computed tomography attenuation, and mechanical properties were assessed via the Pearson correlation. The predictive accuracy of attenuation on compressive properties was assessed via repeated random sub-sampling cross validation. Papain digestion produced significant decreases in glycosaminoglycan content and corresponding differences in attenuation and mechanical properties. Attenuation correlated significantly to glycosaminoglycan content and to all compressive mechanical properties using both Hexabrix and CA4+ . Predictive linear regression models demonstrated a predictive accuracy of attenuation on compressive modulus and stiffness of 79.8-86.0%. Contrast-enhanced micro-computed tomography was highly predictive of compressive mechanical properties in an ex vivo simulation of disc degeneration and may represent an effective modality for indirectly assessing disc compressive properties. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2030-2038, 2018.
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Affiliation(s)
- Michael D Newton
- Orthopaedic Research Laboratory, Beaumont Health, Royal Oak, Michigan
| | | | - Karissa Gawronski
- Orthopaedic Research Laboratory, Beaumont Health, Royal Oak, Michigan
| | - Erik J Davenport
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan
| | - Shannon C Timmons
- Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan
| | - Kevin C Baker
- Orthopaedic Research Laboratory, Beaumont Health, Royal Oak, Michigan.,Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, Michigan
| | - Tristan Maerz
- Orthopaedic Research Laboratory, Beaumont Health, Royal Oak, Michigan.,Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, Michigan.,Department of Orthopaedic Surgery, University of Michigan, 109 Zina Pitcher Place, 48109, Ann Arbor, Michigan
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6
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Bruton LN, Zhou X, Timmons SC, Morrissette JM. Using embryonic zebrafish to evaluate the effects of exposure to novel bisphenol analogues. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.533.63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Laura N. Bruton
- Department of Natural SciencesLawrence Technological UniversitySouthfieldMI
| | - Xinrui Zhou
- Department of Natural SciencesLawrence Technological UniversitySouthfieldMI
| | - Shannon C. Timmons
- Department of Natural SciencesLawrence Technological UniversitySouthfieldMI
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7
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Sleda MA, Albasrawi HK, Timmons SC. Synthesis of Aspirin Analogs for Anticancer and Antibacterial Testing. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.531.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Zhu JS, McCormick NE, Timmons SC, Jakeman DL. Synthesis of α-Deoxymono and Difluorohexopyranosyl 1-Phosphates and Kinetic Evaluation with Thymidylyl- and Guanidylyltransferases. J Org Chem 2016; 81:8816-8825. [DOI: 10.1021/acs.joc.6b01485] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jian-She Zhu
- College
of Pharmacy, Dalhousie University, 5968 College Street, Halifax, Nova Scotia B3H 3J5, Canada
| | - Nicole E. McCormick
- College
of Pharmacy, Dalhousie University, 5968 College Street, Halifax, Nova Scotia B3H 3J5, Canada
| | - Shannon C. Timmons
- Department
of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - David L. Jakeman
- College
of Pharmacy, Dalhousie University, 5968 College Street, Halifax, Nova Scotia B3H 3J5, Canada
- Department
of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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Willbur JF, Vail JD, Mitchell LN, Jakeman DL, Timmons SC. Expression, purification, and characterization of a carbohydrate-active enzyme: A research-inspired methods optimization experiment for the biochemistry laboratory. Biochem Mol Biol Educ 2016; 44:75-85. [PMID: 26710673 DOI: 10.1002/bmb.20928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/08/2015] [Accepted: 09/29/2015] [Indexed: 06/05/2023]
Abstract
The development and implementation of research-inspired, discovery-based experiences into science laboratory curricula is a proven strategy for increasing student engagement and ownership of experiments. In the novel laboratory module described herein, students learn to express, purify, and characterize a carbohydrate-active enzyme using modern techniques and instrumentation commonly found in a research laboratory. Unlike in a traditional cookbook-style experiment, students generate their own hypotheses regarding expression conditions and quantify the amount of protein isolated using their selected variables. Over the course of three 3-hour laboratory periods, students learn to use sterile technique to express a protein using recombinant DNA in E. coli, purify the resulting enzyme via affinity chromatography and dialysis, analyze the success of their purification scheme via SDS-PAGE, assess the activity of the enzyme via an HPLC-based assay, and quantify the amount of protein isolated via a Bradford assay. Following the completion of this experiment, students were asked to evaluate their experience via an optional survey. All students strongly agreed that this laboratory module was more interesting to them than traditional experiments because of its lack of a pre-determined outcome and desired additional opportunities to participate in the experimental design process. This experiment serves as an example of how research-inspired, discovery-based experiences can benefit both the students and instructor; students learned important skills necessary for real-world biochemistry research and a more concrete understanding of the research process, while generating new knowledge to enhance the scholarly endeavors of the instructor.
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Affiliation(s)
- Jaime F Willbur
- From the Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, 48075, USA
| | - Justin D Vail
- From the Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, 48075, USA
| | - Lindsey N Mitchell
- From the Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, 48075, USA
| | - David L Jakeman
- College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Shannon C Timmons
- From the Department of Natural Sciences, Lawrence Technological University, Southfield, Michigan, 48075, USA
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10
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Peltier-Pain P, Timmons SC, Grandemange A, Benoit E, Thorson JS. Warfarin glycosylation invokes a switch from anticoagulant to anticancer activity. ChemMedChem 2011; 6:1347-50. [PMID: 21714096 PMCID: PMC3217245 DOI: 10.1002/cmdc.201100178] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Pauline Peltier-Pain
- Laboratory for Biosynthetic Chemistry, University of Wisconsin National Cooperative Drug Discovery Group Program, Pharmaceutical Sciences Division, School of Pharmacy, 777 Highland Avenue, Madison, WI 53705, (USA)
| | - Shannon C. Timmons
- Laboratory for Biosynthetic Chemistry, University of Wisconsin National Cooperative Drug Discovery Group Program, Pharmaceutical Sciences Division, School of Pharmacy, 777 Highland Avenue, Madison, WI 53705, (USA)
| | - Agnès Grandemange
- Université de Lyon, VetAgro Sup, USC 1233, INRA, 69280 Marcy l’Etoile, (France)
| | - Etienne Benoit
- Université de Lyon, VetAgro Sup, USC 1233, INRA, 69280 Marcy l’Etoile, (France)
| | - Jon S. Thorson
- Laboratory for Biosynthetic Chemistry, University of Wisconsin National Cooperative Drug Discovery Group Program, Pharmaceutical Sciences Division, School of Pharmacy, 777 Highland Avenue, Madison, WI 53705, (USA)
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11
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Timmons SC, Hui JPM, Pearson JL, Peltier P, Daniellou R, Nugier-Chauvin C, Soo EC, Syvitski RT, Ferrières V, Jakeman DL. Enzyme-Catalyzed Synthesis of Furanosyl Nucleotides. Org Lett 2008. [DOI: 10.1021/ol801686c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
A straightforward, efficient method for the chemical synthesis of sugar nucleotides derived from D-mannose and L-fucose precursors is described. This synthetic strategy involves the coupling of acylated glycosyl bromides with nucleoside 5'-diphosphates, which enables the exploitation of neighboring group participation to exclusively prepare diastereomerically pure sugar nucleotides of desired 1,2-trans anomeric configuration. This is the first stereoselective direct coupling approach to sugar nucleotide synthesis. Following deprotection using triethylamine and purification via C18 reversed-phase ion-pair chromatography, UDP- and GDP-alpha-D-mannose as well as UDP- and GDP-beta-L-fucose were obtained in good yield in only four synthetic steps from D-mannose and L-fucose.
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13
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Timmons SC, Thorson JS. Increasing carbohydrate diversity via amine oxidation: aminosugar, hydroxyaminosugar, nitrososugar, and nitrosugar biosynthesis in bacteria. Curr Opin Chem Biol 2008; 12:297-305. [PMID: 18424273 PMCID: PMC2517148 DOI: 10.1016/j.cbpa.2008.03.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [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] [Received: 03/11/2008] [Revised: 03/19/2008] [Accepted: 03/19/2008] [Indexed: 12/14/2022]
Abstract
Bacterial secondary metabolites often contain carbohydrate attachments that play a significant role in conferring biological activity. A small proportion of these bioactive sugars are derived from aminosugar oxidation to ultimately provide hydroxyaminosugars, nitrososugars, and nitrosugars. Recent advances in the elucidation of hydroxyaminosugar-, nitrososugar-, and nitrosugar-containing natural product gene clusters have enabled the proposal of biosynthetic pathways, the in vitro characterization of aminosugar oxidases, and the structure determination of key enzymes. This article focuses upon the key enzymatic transformations in aminosugar, hydroxyaminosugar, nitrososugar, and nitrosugar biosynthesis, as well as the unique chemical reactivity of alkoxyaminosugars, with a particular focus upon developments within the past two years.
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Affiliation(s)
- Shannon C. Timmons
- Laboratory for Biosynthetic Chemistry, Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705; University of Wisconsin National Cooperative Drug Discovery Group Program
| | - Jon S. Thorson
- Laboratory for Biosynthetic Chemistry, Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705; University of Wisconsin National Cooperative Drug Discovery Group Program
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Timmons SC, Jakeman DL. Stereospecific synthesis of sugar-1-phosphates and their conversion to sugar nucleotides. Carbohydr Res 2008; 343:865-74. [PMID: 18299123 DOI: 10.1016/j.carres.2008.01.046] [Citation(s) in RCA: 30] [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: 11/13/2007] [Revised: 01/23/2008] [Accepted: 01/31/2008] [Indexed: 11/16/2022]
Abstract
As Leloir glycosyltransferases are increasingly being used to prepare oligosaccharides, glycoconjugates, and glycosylated natural products, efficient access to stereopure sugar nucleotide donor substrates is required. Herein, the rapid synthesis and purification of eight sugar nucleotides is described by a facile 30 min activation of nucleoside 5'-monophosphates bearing purine and pyrimidine bases with trifluoroacetic anhydride and N-methylimidazole, followed by a 2 h coupling with stereospecifically prepared sugar-1-phosphates. Tributylammonium bicarbonate and tributylammonium acetate were the ion-pair reagents of choice for the C18 reversed-phase purification of 6-deoxysugar nucleotides, and hexose or pentose-derived sugar nucleotides, respectively.
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Affiliation(s)
- Shannon C Timmons
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
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Timmons SC, Hui JPM, Pearson JL, Peltier P, Daniellou R, Nugier-Chauvin C, Soo EC, Syvitski RT, Ferrières V, Jakeman DL. Enzyme-catalyzed synthesis of furanosyl nucleotides. Org Lett 2007; 10:161-3. [PMID: 18092787 DOI: 10.1021/ol7023949] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [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
A bacterial alpha-d-glucopyranosyl-1-phosphate thymidylyltransferase was found to couple four hexofuranosyl-1-phosphates, as well as a pentofuranosyl-1-phosphate, with deoxythymidine 5'-triphosphate, providing access to furanosyl nucleotides. The enzymatic reaction mixtures were analyzed by electrospray ionization mass spectrometry and NMR spectroscopy to determine the anomeric stereochemistry of furanosyl nucleotide products. This is the first demonstration of a nucleotidylyltransferase discriminating between diastereomeric mixtures of sugar-1-phosphates to produce stereopure, biologically relevant furanosyl nucleotides.
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Affiliation(s)
- Shannon C Timmons
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
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16
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Timmons SC, Jakeman DL. On the synthesis of the 2,6-dideoxysugar l-digitoxose. Carbohydr Res 2007; 342:2695-704. [DOI: 10.1016/j.carres.2007.09.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 09/24/2007] [Accepted: 09/28/2007] [Indexed: 10/22/2022]
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Abstract
[structure: see text]. The use of Leloir glycosyltransferases to prepare biologically relevant oligosaccharides and glycoconjugates requires access to sugar nucleoside diphosphates, which are notoriously difficult to efficiently synthesize and purify. We report a novel stereoselective route to UDP- and GDP-alpha-D-mannose as well as UDP- and GDP-beta-L-fucose via direct displacement of acylated glycosyl bromides with nucleoside 5'-diphosphates.
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Abstract
[reaction: see text] Enzymatic approaches to prepare sugar nucleotides are gaining in importance and offer several advantages over chemical synthesis including high yields and stereospecificity. We report the cloning, expression, and purification of two new wild-type thymidylyltransferases and observed catalysis with a wide variety of substrates. Significant product inhibition was not observed with the enzymes studied over a 24 h period, enabling the efficient preparation of 15 sugar nucleotides, clearly demonstrating the synthetic utility of these biocatalysts.
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Affiliation(s)
- Shannon C Timmons
- Department of Chemistry, Dalhousie University, Halifax, N.S., Canada B3H 4J3
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Abstract
We report the first 2,6-dideoxysugar-O-glycosyltransferase with substrate flexibility at the 2 position, confirm the function of a putative NDP-hexose 2,3-dehydratase in the jadomycin B biosynthetic gene cluster and deduce the substrate flexibility of downstream enzymes in l-digitoxose assembly, enabling reprogramming of biosynthetic gene clusters to modify sugar substituents.
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Affiliation(s)
- David L Jakeman
- College of Pharmacy, Dalhousie University, 5968 College St., Halifax, Nova Scotia, Canada.
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Jakeman DL, Farrell S, Young W, Doucet RJ, Timmons SC. Novel jadomycins: incorporation of non-natural and natural amino acids. Bioorg Med Chem Lett 2005; 15:1447-9. [PMID: 15713404 DOI: 10.1016/j.bmcl.2004.12.082] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Revised: 12/22/2004] [Accepted: 12/29/2004] [Indexed: 11/25/2022]
Abstract
Electrospray ionization mass spectrometry of extracts from Streptomyces venezuelae ISP5230 cultures grown on chemically synthesized non-natural L-amino acids, D-amino acids or any of the 20 natural amino acids demonstrated incorporation of the amino acid into a jadomycin B analogue.
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Affiliation(s)
- David L Jakeman
- College of Pharmacy, Dalhousie University, 5968 College street, Halifax, Nova Scotia, B3H 3J5, Canada.
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Abstract
OBJECTIVE To develop and validate a prediction rule screening instrument, easily incorporated into the routine hospital admission assessment, that could facilitate discharge planning by identifying patients at the time of admission who are most likely to need postdischarge medical services. DESIGN Prospective cohort study with separate phases for prediction rule development and validation. SETTING Urban teaching hospital. PATIENTS/PARTICIPANTS General medical service patients, 381 in the derivation phase and 323 in the validation phase, who provided self-reported medical history, health status, and demographic data as a part of their admission nursing assessment, and were subsequently discharged alive. MEASUREMENTS AND MAIN RESULTS Use of postdischarge medical services such as visiting nurse or physical therapy, medical equipment, or placement in a rehabilitation or long-term care facility was determined. A prediction rule based on a patient's age and Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) physical function and social function scores stratified patients with regard to their risk of using postdischarge medical services. In the validation set, the rate of actual postdischarge medical service use was 15% (15 of 97), 36% (39 of 107), and 58% (57 of 98) among patients characterized by the prediction rule as being at "low", "intermediate," and "high" risk of using postdischarge medical services, respectively. CONCLUSIONS This prediction rule stratified general medical patients with regard to their likelihood of needing discharge planning to arrange for postdischarge medical services. Further research is necessary to determine whether prospective identification of patients likely to need discharge planning will make the hospital discharge planning process more efficient.
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Affiliation(s)
- D G Fairchild
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Mass., USA
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