42 research outputs found
Rapid hydrolysis of 2 ',3 '-cAMP with a Cu(II) complex: effect of intramolecular hydrogen bonding on the basicity and reactivity of a metal-bound hydroxide
No full textPT: J; CR: BASHKIN JK, 1993, J CHEM SOC DALT 1207, P3631 BRESLOW R, 1991, P NATL ACAD SCI USA, V88, P4080 BURSTYN JN, 1993, INORG CHEM, V32, P3585 HENGGE AC, 1990, J AM CHEM SOC, V112, P7421 JENCKS WP, 1970, HDB BIOCH MOL BIOL, J150 KIRSCH JF, 1964, J AM CHEM SOC, V86, P837 KOVARI E, 1996, J AM CHEM SOC, V118, P12704 LINKLETTER B, 1995, ANGEW CHEM INT EDIT, V34, P472 LINKLETTER B, 1995, THESIS MCGILL U CANA LIU SH, 1997, ANGEW CHEM INT EDIT, V36, P2678 LIU SH, 1997, TETRAHEDRON LETT, V38, P1107 MACGILLAVRY CH, 1962, INT TABLES XRAY CRYS, V3 MENGER FM, 1987, J AM CHEM SOC, V109, P3145 MORROW JR, 1988, INORG CHEM, V27, P3387 OGAWA S, 1974, J CHEM SOC P1, P976 STERN MK, 1997, INORG CHIM ACTA, V263, P49 SUMAOKA J, 1994, J CHEM SOC CHEM COMM, P1755 TAKASAKI BK, 1994, J AM CHEM SOC, V116, P1121 WONG Y, 1985, INORG CHEM, V24, P3352; NR: 19; TC: 47; J9: J AMER CHEM SOC; PG: 2; GA: 198MPSource type: Electronic(1
Synthesis of protected guanidinium linked dinucleoside incorporable into an oligonucleotide using solid phase DNA methodology
No full textThe synthesis of novel fully protected guanidinium linked dinucleoside for incorporation into oligonucleotide using solid-phase DNA synthesis methodology was developed. The three different protecting groups selected allow different deprotection conditions. (C) 1998 Elsevier Science Ltd. All rights reserved.PT: J; CR: BARAWKAR DA, 1996, NUCLEIC ACIDS RES, V24, P1229 BLASKO A, 1996, J AM CHEM SOC, V118, P7892 BLASKO A, 1997, BIOCHEMISTRY-US, V36, P7821 COOK PD, 1991, ANTI-CANCER DRUG DES, V6, P585 DEMESMAEKER A, 1995, ACCOUNTS CHEM RES, V28, P366 DEMESMAEKER A, 1996, ANGEW CHEM INT EDIT, V35, P2790 DEMPCY RO, 1995, J AM CHEM SOC, V117, P6140 DEMPCY RO, 1996, P NATL ACAD SCI USA, V93, P4326 FATHI R, 1994, NUCLEIC ACIDS RES, V22, P5416 GRYAZNOV SM, 1997, NUCLEOS NUCLEOT, V16, P899 HASHIMOTO H, 1993, J AM CHEM SOC, V115, P7128 HAYAKAWA Y, 1986, J ORG CHEM, V51, P2400 JONES RJ, 1993, J ORG CHEM, V58, P2983 JUST G, 1976, SYNTHESIS-STUTTGART, P457 KEAN JM, 1995, BIOCHEMISTRY-US, V34, P14617 LETSINGER RL, 1988, J AM CHEM SOC, V110, P4470 LINKLETTER B, 1998, IN PRESS BIOORG MED MILLIGAN JF, 1993, J MED CHEM, V36, P1923 NIELSEN PE, 1991, SCIENCE, V254, P1497 PANNECOUQUE C, 1992, TETRAHEDRON LETT, V33, P7609 RICE JS, 1997, BIOCHEMISTRY-US, V36, P399 ROBINSON S, 1997, TETRAHEDRON, V53, P6697 SANGHVI YS, 1993, NUCLEOS NUCLEOT, P311 SANGHVI YS, 1997, NUCLEOS NUCLEOT, V16, P907 SCHMID N, 1995, TETRAHEDRON LETT, V36, P1447 UHLMANN E, 1990, CHEM REV, V90, P543 VANDENDRIESSCHE F, 1993, J CHEM SOC P1, P1567; NR: 27; TC: 18; J9: BIOORG MEDICINAL CHEM LETTER; PG: 4; GA: ZV310Source type: Electronic(1
Synthetic studies towards molecular recognition of guanosine quadruplexes
No full textThe telomere is a guanine-rich region of DNA located at its termini. Each time a DNA molecule is replicated, the telomere gets shortened. Cell death occurs after a telomere has been shortened to a critical length. The telomere may, however, be re-lengthened by the action of the enzyme telomerase. It has been found that in many cases of cancer, the level of telomerase in the cells is extremely high when compared to normal cells. The telomeric region may be linear, or may adopt higher-order structures such as the G-quadruplex. When the telomere is in G-quadruplex form, telomerase is unable to bind to the region and re-lengthen it. By designing molecules that can recognize the G-quadruplex and bind to them, therefore stabilizing them, it is theorized that telomerase inhibition may occur.Through the use of computational methods, an oligomer has been designed to recognize the minor groove of a G-quadruplex. The oligomer has a recognition unit of an aminopyridine group and a peptide nucleic acid (PNA) backbone. The synthetic route to the monomers required for solid-phase synthesis of this oligomer is described in detail.Source: Masters Abstracts International, Volume: 43-02, page: 0538.Adviser: Barry Linkletter
Rapid hydrolysis of RNA with a CU-II complex
No full textPT: J; CR: ANDERSON B, 1977, J AM CHEM SOC, V99, P2652 BARBIER B, 1992, J AM CHEM SOC, V114, P3511 BASHKIN JK, 1994, J AM CHEM SOC, V116, P5981 BRESLOW R, 1986, J AM CHEM SOC, V108, P2655 BRESLOW R, 1989, P NATL ACAD SCI USA, V86, P1746 BRESLOW R, 1991, P NATL ACAD SCI USA, V88, P4080 CONNOLLY JA, 1994, INORG CHEM, V33, P665 GOBEL MW, 1992, ANGEW CHEM INT EDIT, V31, P207 GOBEL MW, 1992, ANGEW CHEM, V104, P217 GUSTAFSON RL, 1959, J AM CHEM SOC, V81, P525 HENDRY P, 1990, INORG CHEM, V29, P92 JUBIAN V, 1992, J AM CHEM SOC, V114, P1120 KOMIYAMA M, 1992, J CHEM SOC CHEM 0415, P640 MAGDA D, 1994, J AM CHEM SOC, V116, P7439 MATSUMOTO Y, 1990, J CHEM SOC CHEM COMM, P1050 MORROW JR, 1992, J AM CHEM SOC, V114, P1903 SCHNEIDER HJ, 1993, ANGEW CHEM INT EDIT, V32, P1716 SCHNEIDER HJ, 1993, ANGEW CHEM, V105, P1773 SMITH J, 1993, J AM CHEM SOC, V115, P362 STERN MK, 1990, J AM CHEM SOC, V112, P5357 SUMAOKA J, 1994, J CHEM SOC CHEM COMM, P1755 TAKASAKI BK, 1993, J AM CHEM SOC, V115, P9337 TAKASAKI BK, 1994, J AM CHEM SOC, V116, P1121 WAHNON D, 1994, J CHEM SOC CHEM COMM, P1441 WALL M, 1993, ANGEW CHEM INT EDIT, V32, P1633 WALL M, 1993, ANGEW CHEM, V105, P1696; NR: 26; TC: 82; J9: ANGEW CHEM INT ED; PG: 3; GA: QM404Source type: Electronic(1
Synthesis and characterization of DNA-functionalized gold nanoparticles to detect lead ions
No full textLead contamination of drinking water is of great concern since it is toxic to human health and
can result in various fatal diseases due to its high toxicity and bioaccumulation. Therefore, the
detection of trace amounts of lead ions in water using a facile, straightforward, and sensitive
home-based test is vitally important so as to monitor and prevent lead ion pollution. Gold
nanoparticles are a well-developed technology that can produce visible color changes when
conditions are changed. G-quadruplexes are 4-stranded DNA structures, which are known to
strongly bind lead ions. Moreover, it is known that DNA oligonucleotides can be adsorbed onto
gold nanoparticles via thiol-gold interactions. The goal of the research project is to make
spherical nucleic acids (SNAs), which have gold nanoparticle cores with G-quadruplexes
arranged to extend outwards from the surface of the gold nanoparticles. We then evaluated their
physical and optical properties for detecting lead ions. We reported the progress in synthesis and
characterization of the G-quadruplex SNA nanoparticles and the observations of their visible
spectra in the presence of lead. This strategy has the potential to benefit society since people will
be able to test water for lead easily in their own homes
Benzylchlorocarbene: UV absorption spectrum, kinetics for 1,2-H migration and mechanism for reaction with acetic acid as determined by combined continuous and laser-flash photolysis
No full textPT: J; CR: BURFIELD DR, 1981, J ORG CHEM, V46, P629 GOULD IR, 1985, ETRAHEDRON, V41, P1987 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 HOUK KN, 1984, J AM CHEM SOC, V106, P4291 HOUK KN, 1984, J AM CHEM SOC, V106, P4293 LIAU MTH, 1987, CHEM DIAZIRINES LIU MTH, UNPUB J AM CHEM SOC LIU MTH, 1984, TETRAHEDRON, V40, P887 LIU MTH, 1989, J CHEM SOC CHEM COMM, V12 MAERCKER A, 1982, CHEM BER, V115, P540 MOSS RA, 1986, J AM CHEM SOC, V108, P7028; NR: 11; TC: 5; J9: LASER CHEM; PG: 9; GA: ED999Source type: Electronic(1
Solid-phase synthesis of deoxynucleic guanidine (DNG) oligomers and melting point and circular dichroism analysis of binding fidelity of octameric thymidyl oligomers with DNA oligomers
No full textAbstract: A practical solid-phase synthesis of deoxynucleic guanidine (DNG), a positively charged DNA backbone analogue, is reported. The nucleoside coupling step in the solid-phase synthesis of DNG involves the attack of a terminal 3'-amine upon an electronically activated 5'-carbodiimide to create a protected guanidinium internucleoside linkage. The activated carbodiimide is synthesized in situ by the mercury(II) abstraction of sulfur from an unsymmetrically substituted thiourea in which one substituent is an electron-withdrawing protecting group and the other is the 5'-nucleoside monomer. This produces, in addition to the carbodiimide, a mercury sulfide precipitate which accumulates in the pores of the solid support, restricting solvent and reagent access and reducing the coupling yields with each successive cycle. This obstacle is overcome by a simple washing step involving a thiophenol solution which readily removes the mercury salt. The addition of this step to the cycle enables DNG oligomers to be synthesized using standard macroporous SPS supports. Coupling yields of 98% were estimated from the HPLC analysis of the product mixtures. An octameric thymidyl oligomer (II) was synthesized and the fidelity of binding to octameric adenyl DNA oligomers containing cytidyl mismatches was determined. Binding was studied by thermal denaturation (Tm), Job plots, and circular dichroism spectrophotometry. The DNG oligomer (II) formed a 2:1 complex with octameric adenyl DNA (III) with a melting temperature of 63 C. Each cytidyl mismatch induced a penalty of 4 to 5 C in the observed melting temperatures. DNA sequences with four or more mismatches showed no base pairing in the presence of II. No association was observed between II and octameric cytidyl DNA. These observations demonstrate that DNG oligomers of moderate length are able to discriminate between complementary and mismatched DNA oligomers.Source type: Electronic(1
On Campus Video, Featuring James Michener, Charlton Heston, Art Linkletter, Chris Christian, Byron Nelson, Roger Staubach, Tom Peters, Anjelica Maria, George Christian, Randy Matson, and Dale Clevinger.
No full textA videorecording of a special presentation of Abilene Christian University\u27s On Campus program, which includes highlights from some of the show\u27s best segments, including interviews with American author James Michener, film actor Charlton Heston, television personality Art Linkletter, singer-songwriter Chris Christian, golf legend Byron Nelson, and former Dallas Cowboy quarterback Roger Staubach. Also appearing are management consultant Tom Peters, international performer Anjelica Maria, former press secretary to President Lyndon B. Johnson, George Christian, Olympic gold-medalist Randy Matson, and the principal french-hornist with the Chicago Symphony Dale Clevinger. The program is hosted by ACU\u27s Vice-President and Dean of Campus Life, Dr. Gary McCaleb
Novel intercalated nanocomposites based on vanadium pentoxide xerogel and sodium iron oxide
No full textEnergy is a vital component of our economies and lifestyle. Unfortunately, most of the current sources of energy are not renewable or environmentally friendly. Among the efforts made to tackle this problem is the development of rechargeable batteries. Rechargeable batteries are transducers that convert chemical energy to electrical energy and vice versa. This project was designed to develop green materials that can be used in lithium/Li-ion batteries. The lithium battery chemistry is currently the most promising battery system because of its superior properties such as high voltage and energy density.The project involved the successful intercalation of highly ionically conducting polymers Poly(oxymethylene-oxyethylene) (POMOE), Poly[oligo(ethylene glycol) oxalate] (POEGO) and Poly[bis-(methoxyethoxyethoxy)phosphazene] (MEEP) into the layered structure vanadium pentoxide xerogel (V 2O5nH2O) and the characterization of the resulting nanocomposites. Intercalation of POMOE and POEGO lead to the bilayer loading of the polymer into the gallery spaces of V2O5nH 2O. This was a significant achievement because the resulting nanocomposites have potential to intercalate more Li-ions compared to monolayer nanocomposites. Intercalation of MEEP into V2O5nH2O leads to nanocomposites whose interlayer expansions increased with increasing concentration of MEEP. The intercalates with higher MEEP concentration were mixed (electronic and ionic) conductors while the intercalates with lower concentration were electronic conductors.Direct intercalation of the ionically conducting polymers into sodium iron oxide (NaFeO2) was not achieved. However, the projects lead to successful de-intercalation (removal) of Na from NaFeO2 via a hydrolysis reaction to produce Na1-xFeO2 (hydrolysis residue) and sodium carbonate hydrate (hydrolysis aqueous solution). The Na1-xFeO2 where x ≈ 1 had been previously predicted as an ideal alternative electrode material to the currently used LiCoO 2 in lithium batteries but had not successfully synthesized. Therefore, this was a major breakthrough in synthesizing this material. The methodology developed here has the advantage of being easily scaled up to industrial production. It was also discovered that the sodium carbonate hydrate had a layered structure and can be intercalated with guest molecules.The new materials reported here were characterized with powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and AC impedance spectroscopy.Source: Masters Abstracts International, Volume: 50-04, page: 2440.Adviser: Rabin Bissessur
Eunicea fusca and Pseudopterogorgia elisabethae as a resource for bioactive diterpenes: A journey through drug discovery, glycosylation chemistry, and chemical proteomics
No full textNatural products have long been recognized for their medicinal value in traditional medicine and remain an important component of modern drug discovery. Known for their immense structural diversity, natural products are secondary metabolites that often exhibit unique pharmacological properties. In the marine habitat, alcyonacean octocorals are a rich source of diterpenes with promising therapeutic potential. For instance, Eunicea fusca contains fuscoside B, a diterpene arabinoside with potent topical anti-inflammatory activity. Notably, fuscoside B selectively inhibits 5-lipoxygenase and has a negligible effect on prostaglandin (PG) biosynthesis. Pseudopteroxazole, an amphilectane diterpene from the octocoral Pseudopterogorgia elisabethae, shows activity against Mycobacterium tuberculosis, the etiologic agent of tuberculosis.
This thesis describes a variety of approaches to discover and develop diterpenes from alcyonacean corals. An investigation of E. fusca collected from Hillsboro Ledge, Florida has led to the discovery of eunicidiol, a topical anti-inflammatory diterpene. The structure of eunicidiol was elucidated by 1D and 2D NMR spectroscopy, while the absolute configuration was unambiguously assigned by the Mosher method. The anti-inflammatory activity of eunicidiol was evaluated by measuring its ability to reduce phorbol myristate acetate (PMA)-induced edema in a mouse ear model. Topical application of a 100 μg/ear dose of eunicidiol significantly reduced edema with activity that was superior to indomethacin, an anti-inflammatory drug serving as an industry benchmark.
A library of novel fuscoside B analogues has been synthesized from fuscol and eunicol using a modified Koenigs-Knorr glycosylation approach. This semisynthesis is the first successful glycosylation of fuscol and has provided the eunicosides, a novel structural class of diterpene glycosides. In addition, glycoside mimics were prepared by introducing ethylene glycol (EG)-based substituents in place of the arabinose moiety. The library of compounds was evaluated for anti-inflammatory activity in the PMA-induced mouse ear edema assay, which demonstrated the remarkable influence of the carbohydrate substituent and its configuration on the in vivo efficacy of this glycoside class.
Pseudopteroxazole has shown activity against resistant strains of M. tuberculosis as well as in the low-oxygen-recovery assay (LORA), a mycobacterial model of non-replicating persistence (NRP). To investigate the antitubercular mechanism of action of pseudopteroxazole, a collection of semisynthetic probes was prepared to identify putative protein targets by affinity chromatography. During the course of this synthesis, structure-activity relationships (SAR) were assessed in order to maintain high binding affinity to the target protein(s). This strategy has led to the identification of several putative targets, including (3R)-hydroxyacyl-ACP dehydratase subunit C (HadC). This result suggests that pseudopteroxazole may exert its antitubercular activity, at least in part, by inhibiting mycolic acid biosynthesis
