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1.
Chemistry ; 16(21): 6365-73, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20411538

RESUMO

Reactions of ethylenedithioglycol (ETG) with Na(2)CO(3), K(2)CO(3), and Cs(2)CO(3) provided the oligothiaethylenethioglycols (nETG): di- (DETG), tri- (TrETG), tetra- (TETG), and pentathiaethylenethioglycol (PETG), along with higher polymers. The most efficient carbonate was K(2)CO(3) and reactions using DETG and TrETG as starting materials--or their mixtures--were also found to afford similar species. This largely unknown oligomerization process was thoroughly explored and potential pathways were put forward. A convenient conversion of ETG to laboratory quantities of the otherwise scarce and/or expensive DETG, TrETG, TETG, and PETG oligomers, in organic or aqueous media was achieved. Notably, this straightforward reaction takes place without the addition of expensive or toxic metal catalysts and with pure water as the solvent, thereby highlighting its potential as a green chemical reaction. Moreover, the process opens up new approaches to dynamic combinatorial libraries (DCLs) of oligomers and macrocycles with manifolded nETG [(SCH(2)CH(2))(n)S] bridges.

2.
Chem Commun (Camb) ; (14): 1686-8, 2008 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-18368165

RESUMO

We herein report our first results on the use of simple acetalation chemistry in the service of dynamic combinatorial libraries (DCLs); the reaction between triethylene glycol and 4-nitrobenzaldehyde afforded a DCL of more than 15 cyclic and acyclic species; all of which were separated and characterized; the smaller macrocyclic compounds were successfully amplified by the use of ammonium ions.

3.
Biochim Biophys Acta ; 1764(5): 955-960, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16795146

RESUMO

Acetohydroxyacid synthase I (AHAS I), one of three isozymes in Escherichia coli catalyzing the first common step in the biosynthesis of branched amino acids, is composed of two kinds of subunits. The large catalytic (B) and small regulatory (N) subunits of the holoenzyme dissociate and associate freely and rapidly and are quite different in size, charge and hydrophobicity, so that high resolution purification methods lead to partial separation of subunits and to heterogeneity. We have prepared several linked AHAS I proteins, in which the large subunit B with a hexahistidine-tag at the N-terminus, was covalently joined by a flexible linker, containing several (X) amino acids, to the small subunit N to form His6-BuXN polypeptides. All linked BuXN polypeptides have similar specific activity, sensitivity to valine and substrate specificity as the wild type holoenzyme. The most successful BuXN linked protein (Bu30N-r) was inserted into and expressed in yeast and its catalytic properties were tested.


Assuntos
Acetolactato Sintase/química , Domínio Catalítico , Engenharia de Proteínas , Subunidades Proteicas/química , Acetolactato Sintase/genética , Sequência de Aminoácidos , Sequência de Bases , Domínio Catalítico/genética , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Dados de Sequência Molecular , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Subunidades Proteicas/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
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