Improvement of an L-threonine producer derived from Brevibacterium flavum using threonine operon of Escherichia coli K-12.
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چکیده
منابع مشابه
L-Threonine dehydrogenase of Escherichia coli K-12.
A rapid method for purifying L-threonine dehydrogenase from Escherichia coli K-12 cells, grown on a medium containing L_-threonine as carbon source, has been developed. The procedure consists of three fractionation steps of which the last is adsorption and elution of the enzyme from a column of Blue dextran-Sepharose. Homogeneous and stable samples of the dehydrogenase are obtained. L-Threonine...
متن کاملTranslational coupling in the threonine operon of Escherichia coli K-12.
In an attempt to express the two distal genes of the Escherichia coli threonine operon, the majority of the first gene in the operon, thrA, was removed and a series of transcriptional fusions were constructed placing the thrB and thrC genes downstream of either the trp or hybrid tac promoter. Analysis of the proteins produced by cells containing these fusions revealed that although the distal g...
متن کاملOperator-constitutive mutants in the threonine operon of Escherichia coli K-12.
Three Escherichia coli K-12 mutant strains resistant to DL-alpha-amino-beta-hydroxyvaleric acid were isolated in which the expression of the thr operon is constitutive. The localization and dominance properties of the mutations involved, called thrO, are those of operator mutations. The gene sequence is OABC as suggested by earlier studies.
متن کاملHomoserine kinase from Escherichia coli K-12: properties, inhibition by L-threonine, and regulation of biosynthesis.
We have partially purified homoserine kinase from a genetically derepressed strain of Escherichia coli K-12. The optimum pH of the enzyme-substrate reaction was 7.8 and the K(m) values for l-homoserine and adenosine 5'-triphosphate were both 3 x 10(-4) M. K(+) (or NH(4) (+)) as well as Mg(2+) were required for its activity. The sedimentation coefficient determined by ultracentrifugation in a su...
متن کاملL-threonine dehydrogenase. Purification and properties of the homogeneous enzyme from Escherichia coli K-12.
L-Threonine dehydrogenase, which catalyzes the conversion of L-threonine to aminoacetone + CO2 presumably via the intermediate formation of alpha-amino-beta-ketobutyrate, has been purified to apparent homogeneity from extracts of a mutant of Escherichia coli K-12 which has constitutively derepressed levels of the enzyme. Three fractionation steps were used including controlled heat denaturation...
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ژورنال
عنوان ژورنال: Agricultural and Biological Chemistry
سال: 1989
ISSN: 0002-1369,1881-1280
DOI: 10.1271/bbb1961.53.2269