Selim and Greenberg (1, 2) achieved a considerable degree of purification of L-serine dehydratase (L-serine hydro-lyase (deaminating), EC 4.2.1.13) from rat liver and demonstrated that this protein preparation contained the cystathionine-synthesizing activity of the liver (L-serine hydro-lyase (adding L-homocysteine), EC 4.2.1.21). These workers (2) also observed activity of their enzyme prepar...

YGL196W of Saccharomyces cerevisiae encodes a putative protein that is unidentified but is predicted to have a motif similar to that of the N-terminal domain of the bacterial alanine racemase. In the present study we found that YGL196W encodes a novel D-serine dehydratase, which belongs to a different protein family from that of the known bacterial enzyme. The yeast D-serine dehydratase purifie...

An experiment was carried out to determine the effect of dietary protein level on the specific activity of hepatic L-threonine dehydrogenase in young growing chicks. Six replicate pens of seven Leghorn chicks were fed semipurified diets containing 23, 27, or 32% CP with identical relative proportions of amino acids in each protein group. Body weights and feed consumption were measured for 3 d, ...

In bacteria, threonine dehydratases could convert L-threonine to 2-ketobutyrate. Some threonine dehydratases contain only a catalytic domain, while others contain an N-terminal catalytic domain and a C-terminal regulatory domain composed of one or two ACT-like subdomains. However, the role of the ACT-like subdomain in threonine dehydratases is not clear. Here, nine different bacterial threonine...

Homoserine dehydrogenase from cell suspension cultures of carrot (Daucus carota L.) has been purified to apparent homogeneity by a combination of selective heat denaturation, ion exchange and gel filtration chromatographies, and preparative gel electrophoresis. Carrot homoserine dehydrogenase is composed of subunits of equal molecular weight (85,000 +/- 5,000). During purification, the enzyme e...

Selim and Greenberg (1, 2) achieved a considerable degree of purification of L-serine dehydratase (L-serine hydro-lyase (deaminating), EC 4.2.1.13) from rat liver and demonstrated that this protein preparation contained the cystathionine-synthesizing activity of the liver (L-serine hydro-lyase (adding L-homocysteine), EC 4.2.1.21). These workers (2) also observed activity of their enzyme prepar...

Amino-acid producers have traditionally been developed by repeated random mutagenesis owing to the difficulty in rationally engineering the complex and highly regulated metabolic network. Here, we report the development of the genetically defined L-threonine overproducing Escherichia coli strain by systems metabolic engineering. Feedback inhibitions of aspartokinase I and III (encoded by thrA a...

The transport routes for threonine in a primate kidney epithelial cell line (BSC-1) grown as monolayer in continuous cell culture were studied. We discovered at least four different transport systems for threonine uptake. The Na(+)-dependent route shows biphasic kinetics with a low and high affinity parameter. The apparent kinetic constants for Km1 and Km2 were 0.3 and 36 mM with apparent Vmax ...

Materials-L-Threonine, L-serine, and pyridosal-P monohydrate were purchased from the California Corporation for Biochemical Research, a-ketobutyric acid from the Nutritional Biochemical Corporation, pyruvic acid from the Fisher Scientific Company, and DESE-cellulose from Eastman Organic Chemicals. nn-Allothreonine and L-allothreonine were kindly furnished by Dr. Alton iLleister of Tufts Univers...

Here we report the draft annotated genome sequence of Escherichia coli XH140A, which is used to produce l-threonine in industry. The genome sequence will allow the characterization of the molecular mechanisms underlying its beneficial properties.