- Covalent capture and electrochemical quantification of pathogenicE. coli
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PathogenicE. colipose a significant threat to public health, as strains of this species cause both foodborne illnesses and urinary tract infections. Using a rapid bioconjugation reaction, we selectively captureE. coliat a disposable gold electrode from complex solutions and accurately quantify the pathogenic microbes using electrochemical impedance spectroscopy.
- Klass, Sarah H.,Sofen, Laura E.,Hallberg, Zachary F.,Fiala, Tahoe A.,Ramsey, Alexandra V.,Dolan, Nicholas S.,Francis, Matthew B.,Furst, Ariel L.
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- Synthesis of new DOPA derivative from l-tyrosine for construction of bioactive compound
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A practical synthetic method of new DOPA derivative was developed with L-tyrosine as starting material. The new DOPA analogue could be used in building bioactive compounds.
- Sun, Dequn,Wan, Peihong,Zhang, Guoqing,Luo, Min
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p. 9407 - 9408
(2013/11/19)
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- Synthesis of L-3-hydroxy-4-methoxy-5-methylphenylalanol
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The L-3-hydroxy-4-methoxy-5-methylphenylalanol, a common subunit of ecteinascidin and safracin family alkaloids, was synthesized from L-tyrosine in eight steps with an overall yield of 50%. Georg Thieme Verlag Stuttgart.
- Demoulin, Nicolas,Zhu, Jieping
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p. 466 - 468
(2009/08/09)
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- Use of a boroxazolidone complex of 3-iodo-l-tyrosine for palladium-catalyzed cross-coupling
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Complexation of 3-iodo-L-tyrosine with 9-borabicyclo[3.3.1]nonane (9-BBN) provides a convenient substrate for a palladium-catalyzed coupling reaction. The complex is stable to silica gel chromatography (hexanes/ethyl acetate), dilute triethylamine in THF, and potassium fluoride in DMF. The desired product, 3-ethynyl-L-tyrosine, was released from the complex by simply diluting its solution in methanol with chloroform. Interestingly, the complex remains stable in solutions of either methanol or chloroform individually.
- Walker IV, William H.,Rokita, Steven E.
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p. 1563 - 1566
(2007/10/03)
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- Chemical approaches to protein engineering 20: The transformation of coded amino acid tyrosine to pro-templates having metal uptake potential in peptide/protein segments
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From vantage of inorganic chemistry, the inability of any of the coded amino acid side chains to carry metal ions should appear as a grave omission in the genetic code, particularly since, metallo-enzymes play a pivotal role in diverse facets of life processes. The ready transformation of the coded amino acid tyrosine to metal uptake systems forms the core of the present work. 3-Acetyl-tyrosine [Tyr(3-Ac)]- readily derived from tyrosine is amenable to normal protocols in peptide synthesis and offers ideal ligand dispositions to craft protemplates. This aspect has been illustrated by three broad strategies. The reaction of Tyr(3-Ac) with AEH, the mono Schiff base of acetylacetone and ethylenediamine (EDA), yields the protemplates II [TYr(3-Ac)-AEH] which can also be conveniently assembled, in situ, from acetylacetone, EDA and Tyr(3-Ac). Tripeptide, where Tyr(3-Ac) is flanked by Ala and Ser has been prepared and protemplate formation demonstrated in a peptide environment. Thus, either by normal peptide synthesis or by insertion of peptides containing Tyr(3-Ac), active sites for metal uptake can be constructed, thereby, in principle, obviating the need for 50-70 residues normally required. Protemplates for metal uptake can be readily crafted by cross linking of Tyr(3-Ac) with EDA. This has also been illustrated with Ala-Tyr(3-Ac)-Ser-OMe. Thus, peptides where Tyr(3-Ac) is placed at appropriate locations, with EDA, can provide conformationally restrained metal uptake systems. Conversely, the oxime of Tyr(3-Ac) as well as the Schiff bases with β-ethanolamine and Gly-OMe can bring together proximate residues by metal complexation. This aspect has been experimentally realized. The protemplates from Tyr(3-Ac) [Schiff bases with AEH / EDA / β-ethanolamine / Gly-OMe / and oximes] readily take up Cu(II), Co(II), and Ni(II) to form stable, well defined templates. The EPR spectra of the Cu(II) templates are that for typical square planar complexes, although in few sterically crowded examples rhombohedral distortion was seen. The observed A and g parameters compared favorably with that reported for metalloproteins, with particular closeness to laccase. Cyclic voltammetric studies were complicated by incursion of ligand oxidation, although in two cases clear E° values of 340 mV and 305 mV were obtained, which lie in the range reported for metallo-proteins. The Ni(II) templates exhibited the expected 1H NMR profile; in one example, coordination with two water molecules was seen. The Co(II) templates exhibited typical d-d transition at ~600 nm in the visible spectrum.
- Ranganathan,Tamilarasu
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p. 1081 - 1103
(2007/10/03)
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- A non-enzymatic synthesis of (S)-(-)-rosmarinic acid and a study of a biomimetic route to (+)-rabdosiin
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The synthesis of (S)-(-)-rosmarinic acid (30) in 9% overall yield is described. The synthesis was achieved by a convergent route in which 3-(3′,4′-dihydroxyphenyl)-(S)-lactic acid (23) and caffeic acid (25), both appropriately protected, were coupled to produce a pentaallyl precursor 29, which was then deprotected to give (S)-(-)-rosmarinic acid (30). A triallyl derivative 35 was similarly prepared and converted to (+)-rabdosiin (41) and its (1R,2S) isomer (42) via a biomimetic oxidative free radical coupling-cyclization followed by deallylation. The coupling-cyclization gave a ratio of rabdosiin diastereomers unlike that found in nature. A preliminary study showed that methyl (R)-mandelyl sinapate (15) could be dimerized diastereoselectively to give a 1,2-trans thomasidioate diester (16). The synthesis of (S)-(-)-rosmarinic aid (30) in 9% overall yield is described. The synthesis was achieved by a convergent route in which 3- (3',4'-dihydroxyphenyl)-(S)-lactic acid (23) and caffeic acid (25), both appropriately protected, were coupled to produce a pentaallyl precursor 29, which was then deprotected to give (S)-(-)-rosmarinic acid (30). A triallyl derivative 35 was similarly prepared and converted to (+)-rabdosiin (41) and its (1R,2S) isomer (42) via a biomimetic oxidative free radical coupling- cyclization followed by deallylation. The coupling-cyclization gave a ratio of rabdosiin diastereomers unlike that found in nature. A preliminary study showed that methyl (R)-mandelyl sinapate (15) could be dimerized diastereoselectively to give a 1,2-trans thomasidioate diester (16).
- Bogucki, David E.,Charlton, James L.
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p. 1783 - 1794
(2007/10/03)
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