Measurement of l-Threonine Aldolase Activity in Rat Liver

1979 ◽  
Vol 7 (6) ◽  
pp. 1274-1276 ◽  
Author(s):  
MICHAEL I. BIRD ◽  
PETER B. NUNN
Keyword(s):  
Rat Liver ◽  
Threonine Aldolase ◽  
Aldolase Activity

scholarly journals l-threonine aldolase is not a genuine enzyme in rat liver

1986 ◽  
Vol 237 (1) ◽  
pp. 187-190 ◽  
Author(s):  
Y G Yeung
Keyword(s):  
Lactate Dehydrogenase ◽  
Alcohol Dehydrogenase ◽  
Rat Liver ◽  
Liver Extract ◽  
Threonine Dehydratase ◽  
Threonine Aldolase ◽  
Cytosolic Extract ◽  
Aldolase Activity ◽  
Nadph Dehydrogenase ◽  
Coupled Assay

Activity of L-threonine aldolase in rat liver cytosolic extract was not affected by the omission of alcohol dehydrogenase in a previously established NADPH-linked alcohol dehydrogenase-coupled assay. The liver extract was able to catalyse the dehydrogenation of NADPH with either acetaldehyde (a product of L-threonine aldolase action) or 2-oxobutyrate (a product of L-threonine dehydratase action). When the liver extract was chromatographed on a Sephacryl S-200 column, no threonine aldolase activity was detected in the eluate. However, activity of threonine aldolase re-appeared when the fractions with highest activity of lactate dehydrogenase and threonine dehydratase were mixed. Activity of threonine aldolase could also be abolished by removing threonine dehydratase from the liver extract with a specific antibody. Hence L-threonine aldolase should not be a genuine enzyme in the rat liver, and the apparent enzyme activity may result from a combined effect of threonine dehydratase and lactate dehydrogenase (or an oxo acid-linked NADPH dehydrogenase) in the liver cytosolic extract.

Threonine aldolase and alcohol dehydrogenase activities in Lactobacillus bulgaricus and Lactobacillus acidophilus and their contribution to flavour production in fermented milks

1983 ◽  
Vol 50 (3) ◽  
pp. 375-379 ◽  
Author(s):  
Valerie M. Marshall ◽  
Wendy M. Cole
Keyword(s):  
Alcohol Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Lactobacillus Acidophilus ◽  
Lactobacillus Bulgaricus ◽  
Flavour Compound ◽  
Threonine Aldolase ◽  
Fortified Milk ◽  
Alcohol Dehydrogenase Activity ◽  
Aldolase Activity ◽  
Acetaldehyde Production

SummaryCell-free extracts of both Lactobacillus bulgaricus and L. acidophilus demonstrated threonine aldolase activity, the end product of which was acetaldehyde, the major flavour compound of yoghurt. L. acidophilus also possessed an alcohol dehydrogenase activity capable of reducing acetaldehyde so that little yoghurt flavour was present in milks fermentation with this organism. Addition of threonine to fortified milk before fermentation with L. acidophilus increased acetaldehyde production and resulted in a well flavoured product similar to that of yoghurt made with L. bulgaricus. The contribution of these 2 enzymes to flavour production is discussed.

scholarly journals Effect of Threonine and Glycine Concentrations on Threonine Aldolase Activity of Yogurt Microorganisms During Growth in a Modified Milk Prepared by Ultrafiltration

1989 ◽  
Vol 72 (5) ◽  
pp. 1142-1148 ◽  
Author(s):  
Romina M. Marranzini ◽  
Ronald H. Schmidt ◽  
Rachel B. Shireman ◽  
Maurice R. Marshall ◽  
John A. Cornell
Keyword(s):  
Threonine Aldolase ◽  
Aldolase Activity

scholarly journals Bacterial catabolism of threonine. Threonine degradation initiated by l-threonine acetaldehyde-lyase (aldolase) in species of Pseudomonas

1977 ◽  
Vol 166 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Stephen C. Bell ◽  
John M. Turner
Keyword(s):  
Reductase Activity ◽  
Growth Conditions ◽  
Serine Hydroxymethyltransferase ◽  
Threonine Aldolase ◽  
Highly Active ◽  
Activity Ratios ◽  
Exclusion Chromatography ◽  
Mammalian Origin ◽  
Aldolase Activity ◽  
Single Enzyme

1. The route of l-threonine degradation was studied in four strains of the genus Pseudomonas able to grow on the amino acid and selected because of their high l-threonine aldolase activity. Growth and manometric results were consistent with the cleavage of l-threonine to acetaldehyde+glycine and their metabolism via acetate and serine respectively. 2. l-Threonine aldolases in these bacteria exhibited pH optima in the range 8.0–8.7 and Km values for the substrate of 5–10mm. Extracts exhibited comparable allo-l-threonine aldolase activities, Km values for this substrate being 14.5–38.5mm depending on the bacterium. Both activities were essentially constitutive. Similar activity ratios in extracts, independent of growth conditions, suggested a single enzyme. The isolate Pseudomonas D2 (N.C.I.B. 11097) represents the best source of the enzyme known. 3. Extracts of all the l-threonine-grown pseudomonads also possessed a CoA-independent aldehyde dehydrogenase, the synthesis of which was induced, and a reversible alcohol dehydrogenase. The high acetaldehyde reductase activity of most extracts possibly resulted in the underestimation of acetaldehyde dehydrogenase. 4. l-Serine dehydratase formation was induced by growth on l-threonine or acetate+glycine. Constitutively synthesized l-serine hydroxymethyltransferase was detected in extracts of Pseudomonas strains D2 and F10. The enzyme could not be detected in strains A1 and N3, probably because of a highly active ‘formaldehyde-utilizing’ system. 5. Ion-exchange and molecular exclusion chromatography supported other evidence that l-threonine aldolase and allo-l-threonine aldolase activities were catalysed by the same enzyme but that l-serine hydroxymethyltransferase was distinct and different. These results contrast with the specificities of some analogous enzymes of mammalian origin.

Survey of the inhibitory effects of glycine on threonine aldolase activity of yogurt microorganisms

1989 ◽  
Vol 37 (5) ◽  
pp. 1215-1216 ◽  
Author(s):  
Ronald H. Schmidt ◽  
Laura B. Kennedy ◽  
Ellen B. McMullan ◽  
Edward R. Mason
Keyword(s):  
Inhibitory Effects ◽  
Threonine Aldolase ◽  
Aldolase Activity

scholarly journals Melon ethylene-mediated transcriptome and methylome dynamics provide insights to volatile production

2020 ◽  
Author(s):  
Ari Feder ◽  
Chen Jiao ◽  
Navot Galpaz ◽  
Julia Vrebalov ◽  
Yimin Xu ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Large Scale ◽  
Cytosine Methylation ◽  
Acc Oxidase ◽  
Threonine Aldolase ◽  
Genome Methylation ◽  
Ester Biosynthesis ◽  
Small Set ◽  
Aldolase Activity ◽  
Mutant Complementation

AbstractDuring climacteric ripening large-scale transcriptional modifications are governed by ethylene. While ripening-related chromatin modifications are also known to occur, a direct connection between these factors has not been demonstrated. We characterized ethylene-mediated transcriptome modification, genome methylation dynamics, and their relation to organoleptic modifications during fruit ripening in the climacteric melon and an ethylene repressed line where the fruit-specific ACC oxidase 1 (ACO1) gene was targeted by antisense. The ACO1 antisense line exhibited mainly reduced transcriptional repression of ripening-related genes associated with DNA CHH hypomethylation at the onset of ripening. Additionally, transcription of a small set of ethylene-induced genes, including known ripening-associated genes, was inhibited by ACO1 repression and this inhibition was associated with CG hypermethylation. In the ACO1 antisense line, the accumulation of aromatic compounds, which are mainly derived from the catabolism of amino acids, is known to be inhibited. One of the ethylene-mediated transcriptionally up-regulated genes, CmTHA1, encoding a threonine aldolase, exhibited differential cytosine methylation. Threonine aldolase catalyzes the conversion of L-threonine/L-allo threonine to glycine and acetaldehyde and thus is likely involved in threonine-dependent ethyl ester biosynthesis. Yeast mutant complementation and incubation of melon discs with labeled threonine verified CmTHA1 threonine aldolase activity, revealing an additional ethylene-dependent amino acid catabolism branch involved in climacteric melon ripening.

scholarly journals Chemoenzymatic synthesis of 3-ethyl-2,5-dimethylpyrazine by L-threonine 3-dehydrogenase and 2-amino-3-ketobutyrate CoA ligase/L-threonine aldolase

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tomoharu Motoyama ◽  
Shogo Nakano ◽  
Fumihito Hasebe ◽  
Ryo Miyata ◽  
Shigenori Kumazawa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Chemical Reactions ◽  
Maillard Reaction ◽  
Condensation Reaction ◽  
Chemoenzymatic Synthesis ◽  
Moderate Reaction ◽  
Threonine Aldolase ◽  
Coa Ligase ◽  
Low Concentrations ◽  
Aldolase Activity

AbstractPyrazines are typically formed from amino acids and sugars in chemical reactions such as the Maillard reaction. In this study, we demonstrate that 3-ethyl-2,5-dimethylpyrazine can be produced from L-Thr by a simple bacterial operon. We conclude that EDMP is synthesized chemoenzymatically from L-Thr via the condensation reaction of two molecules of aminoacetone and one molecule of acetaldehyde. Aminoacetone is supplied by L-threonine 3-dehydrogenase using L-Thr as a substrate via 2-amino-3-ketobutyrate. Acetaldehyde is supplied by 2-amino-3-ketobutyrate CoA ligase bearing threonine aldolase activity from L-Thr when CoA was at low concentrations. Considering the rate of EDMP production, the reaction intermediate is stable for a certain time, and moderate reaction temperature is important for the synthesis of EDMP. When the precursor was supplied from L-Thr by these enzymes, the yield of EDMP was increased up to 20.2%. Furthermore, we demonstrate that this reaction is useful for synthesizing various alkylpyrazines.

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