- Biosynthesis of a site-specific DNA cleaving protein
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An E. coli catabolite activator protein (CAP) has been converted into a sequence-specific DNA cleaving protein by genetically introducing (2,2′-bipyridin-5-yl)alanine (Bpy-Ala) into the protein. The mutant CAP (CAP-K26Bpy-Ala) showed comparable binding affinity to CAP-WT for the consensus operator sequence. In the presence of Cu(II) and 3-mercaptopropionic acid, CAP-K26Bpy-Ala cleaves double-stranded DNA with high sequence specificity. This method should provide a useful tool for mapping the molecular details of protein-nucleic acid interactions. Copyright
- Hyun, Soo Lee,Schultz, Peter G.
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Read Online
- Directed evolution using proteins comprising unnatural amino acids
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The invention provides methods and compositions for screening polypeptide libraries that include variants comprising unnatural amino acids. In addition, the invention provides vector packaging systems and methods for packaging a nucleic acid in a vector. Compositions of vectors produced by the methods and systems are also provided.
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Page/Page column 40
(2016/02/26)
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- Electrochemical coupling of mono and dihalopyridines catalyzed by nickel complex in undivided cell
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One step nickel-catalyzed electroreductive homocoupling among 2-bromopicolines and 2-bromopyridine has been investigated by our group in an undivided cell and using zinc or iron as sacrificial anode. In this work, it was developed mono and dihalopyridines coupling to obtain possible products from heterocoupling. A series of reactions were carried out in order to develop a synthetic method for the preparation of unsymmetrical 2,2′-bipyridines and 2,2′:6′,2″-terpyridines. Statistical yields (50%) were observed for 2-bromopyridines/2-bromo-6-methylpyridine heterocoupling. In a preliminary study devoted to terpyridines preparation, good results were obtained for 2,6-dihalopyridines homocoupling, affording 2,6-dichloro-2, 2′-bipyridine (46%) and 2,6-dibromo-2,2′-bipyridine (56%), at controlled reaction time. At major reaction time, it was observed that the direct electroreduction of the 2,6′-dihalo-2,2′-bipyridines intermediates and 2,6″-dihalo-2,2′:6′,2″-terpyridines products on the cathode surface. A reasonable isolated product yield of 6,6″-dimethyl-2,2′:6′,2″-terpyridine (10%) was only observed in the reaction between 2,6-dichloropyridine and 2-bromo-6- methylpyridine (1:2).
- Oliveira, Jadson L.,Silva, Maria J.,Florêncio, Tupolevck,Urgin, Karne,Sengmany, Stéphane,Léonel, Eric,Nédélec, Jean-Yves,Navarro, Marcelo
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experimental part
p. 2383 - 2390
(2012/04/17)
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- Heteroaryl cross-coupling as an entry toward the synthesis of lavendamycin analogues: A model study
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(Chemical Equation Presented) ABC analogues of the antitumor antibiotic lavendamycin, which contain the key metal chelation site and redox-active quinone unit essential for biological activity, were prepared via the palladium(0)-catalyzed cross-coupling reaction of various 2-haloheteroaromatics with 2-stannylated pyridines and quinolines. Using the Stille reaction, 2-bromo substituted quinolines and 1-bromoisoquinolines were found to undergo efficient coupling with 2-pyridinylstannanes to provide unsymmetrical heterobiaryl derivatives. While the Stille reaction using the reverse coupling partners (i.e., 2-quinolinylstannanes and haloheteroaromatics) had not received much attention in the literature, we found that this alternative coupling reaction efficiently provided several new heterobiaryl derivatives. The gold-catalyzed intramolecular cycloisomerization of N-(prop-2-ynyl)-1H-indole-2-carboxamide smoothly afforded a β-carbolinone derivative that was subsequently used for a Pd(0)-catalyzed cross-coupling directed toward the synthesis of lavendamycin analogues.
- Verniest, Guido,Wang, Xingpo,De Kimpe, Norbert,Padwa, Albert
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supporting information; experimental part
p. 424 - 433
(2010/03/30)
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- In situ formation and reaction of 2-pyridylboronic esters
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2-Pyridylboronic esters were generated by cross-coupling 2-bromopyridines with bis(pinacolato)diboron in the presence of a base and palladium catalyst. The boronic esters reacted in situ with unreacted 2-bromopyridines to afford high yields of 2,2′-bipyridines as homocoupled products. Depending upon the reaction conditions, varying amounts of protodeboronated products were also observed. An attempted cross-coupling between two different 2-bromopyridines produced a nearly statistical mixture of homo- and cross-coupled products.
- Fuller, Amelia A.,Hester, Heidi R.,Salo, Eric V.,Stevens, Erland P.
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p. 2935 - 2938
(2007/10/03)
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- Functionalized 2,2′-bipyridines and 2,2′:6′,2″-terpyridines via stille-type cross-coupling procedures
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Stille-type cross-coupling procedures are utilized in order to prepare a variety of functionalized 2,2′-bipyridines and 2,2′:6′,2″-terpyridines. Such N-heterocyclic compounds are of great interest as chelating ligands for transitionmetal ions in the field of supramolecular chemistry. Various mono- and disubstitued 2,2′-bipyridines were synthesized in high yields and multigram scales using a modular design principle. The terpyridines may be functionalized in one step with different substituents at the outer pyridine rings and at the 4′-position of the centered ring, leading to multifunctionalized compounds. The initially obtained methyl ester and ethyl ester groups can be simply converted into bromomethyl and hydroxymethyl groups which allow further functionalization reactions.
- Heller, Marcel,Schubert, Ulrich S.
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p. 8269 - 8272
(2007/10/03)
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- Stille-type cross-coupling - An efficient way to various symmetrically and unsymmetrically substituted methyl-bipyridines: Toward new ATRP catalysts
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(matrix presented) Various mono- and disubstituted 2,2′-bipyridines were synthesized in high yields and multigram scales utilizing Stille-type coupling procedures. The corresponding bromo-picoline and tributyltin-picoline building blocks were prepared from commercially available amino-picoline compounds. As first examples of metal complexes, 4,5′-dimethyl-2,2′-bipyridine was reacted with copper(II) and iron(II) ions and investigated as catalyst in ATRP.
- Schubert, Ulrich S.,Eschbaumer, Christian,Heller, Marcel
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p. 3373 - 3376
(2007/10/03)
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