Formation of acetaldehyde from threonine by lactic acid bacteria

1976 ◽  
Vol 43 (1) ◽  
pp. 75-83 ◽  
Author(s):  
G. J. Lees ◽  
G. R. Jago
Keyword(s):  
Free Amino ◽  
Thiol Group ◽  
Nutritional Requirement ◽  
Threonine Dehydratase ◽  
Threonine Aldolase ◽  
Streptococcus Cremoris ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
Dehydratase Activity ◽  
Derivatives Of

SummaryGroup N streptococci were found to cleave threonine to form acetaldehyde and glycine. Threonine aldolase, the enzyme catalysing this reaction, was found in all strains exceptStreptococcus cremorisZ8, an organism which had been shown previously to have a nutritional requirement for glycine. The enzyme was strongly inhibited by glycine and cysteine. The inhibition showed characteristics of allosteric inhibition and was pH-dependent. Inhibition by glycine, but not by cysteine, was highly specific. Analogues and derivatives of cysteine which contained a thiol group and a free amino group inhibited the activity of threonine aldolase. The presence of a carboxyl group was not necessary for inhibition. The cleavage of threonine by wholecell suspensions was stimulated by either an energy source to aid transport, or by rendering the cells permeable to substrate with oleate. Threonine did not appear to be degraded by enzymes other than threonine aldolase, as threonine dehydratase activity was low and NAD- and NADP-dependent threonine dehydrogenases were absent.

scholarly journals Localization and interconversion of tetrahydropteroylglutamates in isolated pea mitochondria

1972 ◽  
Vol 128 (1) ◽  
pp. 29-40 ◽  
Author(s):  
M. T. Clandinin ◽  
E. A. Cossins
Keyword(s):  
Amino Acids ◽  
Free Amino ◽  
Lactobacillus Casei ◽  
Sucrose Density Gradient ◽  
Mitochondrial Fraction ◽  
C1 Metabolism ◽  
Isolated Mitochondria ◽  
Feeding Experiments ◽  
Pteroylglutamic Acid ◽  
Derivatives Of

1. Mitochondria were extracted from 4-day-old pea cotyledons and purified on a sucrose density gradient. 2. Microbiological assay of the purified mitochondrial fraction with Lactobacillus casei (A.T.C.C. 7469), Streptococcus faecalis (A.T.C.C. 8043) and Pediococcus cerevisiae (A.T.C.C. 8081) revealed a discrete pool of conjugated and unconjugated derivatives of tetrahydropteroylglutamic acid. 3. Solubilization and chromatographic studies of the mitochondrial fraction demonstrated the presence of formylated and methylated derivatives, 10-formyltetrahydropteroylmonoglutamic acid, 5-formyltetrahydropteroylmonoglutamic acid and 5-formyltetrahydropteroyldiglutamic acid being the major derivatives present. 4. The principal mitochondrial pteroylglutamates were labelled when dry seeds were allowed to imbibe [2-14C]pteroylglutamic acid and 5-[methyl-14C]-methyltetrahydropteroylmonoglutamic acid. 5. The ability of isolated mitochondria to catalyse oxidation and reduction of tetrahydropteroylglutamic acid derivatives was demonstrated in feeding experiments in which [14C]formaldehyde, [3-14C]serine, sodium [14C]formate, 5-[methyl-14C]methyltetrahydropteroylmonoglutamic acid or [2-14C]-glycine served as C1 donor. In addition,14C was incorporated into free amino acids related to C1 metabolism.

ACTIVE SITE-SELECTIVE LABELING OF THROMBIN WITH FLUORESCENCE PROBES USING THI0ESTER DERIVATIVES OF PEPTIDE-CHL0R0METHYL KETONES

1987 ◽  
Author(s):  
Paul E Bock
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Thiol Group ◽  
Fluorescence Probes ◽  
Red Cross ◽  
Chloromethyl Ketone ◽  
Human Thrombin ◽  
Reaction Stoichiometry ◽  
Site Selective ◽  
Derivatives Of

Active site-directed inactivation of a serine protease with a thioester derivative of a peptide-chloromethyl ketone followed by reaction of the unique thiol group generatedin the presence of hydroxylamine with a fluorophore-iodoacetamide hasbeen investigated as a new method for covalent incorporation of extrinsic fluorescence probes into the active sites of blood coagulation proteases. The specificity of labeling by this method was evaluated by quantitation of the reactions between human thrombin, acetylthioacetyl-D-Phe-Pro-ArgCH2Cl (ATA-FPRCK) and 5-iodoacetamidofluorescein(IAF).ATA-FPRCK was synthesized by reaction of FPRCK with succinimidylacetylthioacetate and purified by chromatography on SP-Sephadex and Sephadex G10. Titrations of the loss of thrombin chromogenic substrate activity with ATA-FPRCK were linear, with end points of 1.1-1.2 mol ATA-FPRCK added/mol active sites, consistent with a reaction stoichiometry of 1 and the ∽90% purity of the compound estimated by reverse-phase HPLC.Inactivation of thrombin wasquantitatively correlated with incorporation of the thioester, with a maximum of 1.04 mol/mol active sites.IAF labeling of ATA-FPR-thrombin inthe presence of 0.1M NH20H yielded a maximu of 0.96 mol IAF incorporated/mol active sites in a reaction accompanied by loss of the thiol group. Incorporation of ATA-FPRCK wasdependent on thefunctional thrombin active site, asdemonstrated by less than 4%thioester or IAF incorporation for the enzyme previously inactivated with FPRCK. I conclude that active site-selective fluorescence labelingcan be achieved by the method described here with the advantage of a wide choice in the properties of theprobe incorporated. In addition, a 2.3-fold difference in fluorescenceintensity was observed for 2,6-ANS derivatives of ATA-FPR-thrombin andATA-D-Phe-Phe-Arg-thrombin, indicating that the spectral properties ofenvironmentally sensitive fluorescence probes are influenced by the structure of the peptide inhibitor.Supported in part by a grant from the American National Red Cross.

scholarly journals Overproduction of Threonine Aldolase Circumvents the Biosynthetic Role of Pyruvate Decarboxylase in Glucose-Limited Chemostat Cultures of Saccharomyces cerevisiae

2003 ◽  
Vol 69 (4) ◽  
pp. 2094-2099 ◽  
Author(s):  
Antonius J. A. van Maris ◽  
Marijke A. H. Luttik ◽  
Aaron A. Winkler ◽  
Johannes P. van Dijken ◽  
Jack T. Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Alternative Pathway ◽  
Pyruvate Decarboxylase ◽  
Lysine Biosynthesis ◽  
Carbon Limitation ◽  
Growth Media ◽  
Nutritional Requirement ◽  
Acetyl Coa ◽  
Threonine Aldolase ◽  
Chemostat Cultures

ABSTRACT Pyruvate decarboxylase-negative (Pdc−) mutants of Saccharomyces cerevisiae require small amounts of ethanol or acetate to sustain aerobic, glucose-limited growth. This nutritional requirement has been proposed to originate from (i) a need for cytosolic acetyl coenzyme A (acetyl-CoA) for lipid and lysine biosynthesis and (ii) an inability to export mitochondrial acetyl-CoA to the cytosol. To test this hypothesis and to eliminate the C2 requirement of Pdc− S. cerevisiae, we attempted to introduce an alternative pathway for the synthesis of cytosolic acetyl-CoA. The addition of l-carnitine to growth media did not restore growth of a Pdc− strain on glucose, indicating that the C2 requirement was not solely due to the inability of S. cerevisiae to synthesize this compound. The S. cerevisiae GLY1 gene encodes threonine aldolase (EC 4.1.2.5), which catalyzes the cleavage of threonine to glycine and acetaldehyde. Overexpression of GLY1 enabled a Pdc− strain to grow under conditions of carbon limitation in chemostat cultures on glucose as the sole carbon source, indicating that acetaldehyde formed by threonine aldolase served as a precursor for the synthesis of cytosolic acetyl-CoA. Fractionation studies revealed a cytosolic localization of threonine aldolase. The absence of glycine in these cultures indicates that all glycine produced by threonine aldolase was either dissimilated or assimilated. These results confirm the involvement of pyruvate decarboxylase in cytosolic acetyl-CoA synthesis. The Pdc− GLY1 overexpressing strain was still glucose sensitive with respect to growth in batch cultivations. Like any other Pdc− strain, it failed to grow on excess glucose in batch cultures and excreted pyruvate when transferred from glucose limitation to glucose excess.

Dipeptide utilization by starter streptococci

1977 ◽  
Vol 44 (2) ◽  
pp. 309-317 ◽  
Author(s):  
B. A. Law
Keyword(s):  
Amino Acids ◽  
Transport System ◽  
Free Amino Acids ◽  
Free Amino ◽  
Essential Amino Acids ◽  
Exponential Phase ◽  
Whole Cells ◽  
Streptococcus Cremoris ◽  
Defined Media ◽  
Hydrolysis Of

SummaryOf 8 strains ofStreptococcus cremoristested, 5 grew almost as well in defined media in which various essential amino acids were supplied in dipeptides as they did in media containing the equivalent free amino acids. The remainder grew poorly or not at all in the peptide-containing media. Growth of peptide-utilizing strains was inhibited by also including structurally-related dipeptides in the medium, presumably due to competition for uptake by transport system carriers. Both types of starters produced cell-free dipeptidases recoverable from the medium of exponential phase cultures. Addition of the partly-purified extracellular dipeptidases to dipeptidecontaining test media initiated growth in strains unable to use peptides.Str. lactisgrew in defined peptide media, but the further addition of structurally-related dipeptides did not inhibit growth, either bcause each dipeptide was transported by a specific carrier or because peptides were hydrolysed extracellularly. The presence of cell-bound extracellular dipeptidase was indicated by the hydrolysis of dipeptides with washed whole cells in buffer. This was not observed withStr. cremorisstrains.

Mutation to auxotrophy and prototrophy as related to symbiotic effectiveness in Rhizobium leguminosarum and R. trifolii

1969 ◽  
Vol 15 (6) ◽  
pp. 611-622 ◽  
Author(s):  
E. A. Schwinghamer
Keyword(s):  
Rhizobium Leguminosarum ◽  
Auxotrophic Mutant ◽  
Metabolic Inhibitors ◽  
Nutritional Requirement ◽  
Metabolic Defects ◽  
Resistant Mutants ◽  
The Relationship ◽  
Derivatives Of ◽  
Very High

Auxotrophs were isolated from four effective strains of Rhizobium leguminosarum and R. trifolii for a study of the relationship between metabolic defects and loss of ability for symbiosis. Most auxotrophs were isolated indirectly by prior isolation of mutants for resistance to metabolic inhibitors, especially D-alanine and D-histidine. The likelihood of some nutritional requirement was greatly increased among such resistant mutants, and was very high for derivatives of the R. trifolii strains. The complexity of growth factor requirement varied greatly between auxotrophs, and few had simple requirements. The most common requirement was for vitamins, notably thiamine. Partial or full restoration of effectiveness in symbiosis often accompanied reversion to prototrophy in some ineffective auxotrophs. The frequency of some degree of restoration among prototrophs varied from 0% to 100%, depending on the auxotrophic mutant involved. In one ineffective auxotroph of R. trifolii strain T1 the level of reversion (partial to complete) in vitro varied considerably and generally paralleled the degree of restoration of effectiveness. Biochemical deficiency appeared to be meaningfully related to impaired symbiosis in some auxotrophs but the relationship was probably incidental in most others. These auxotroph–prototroph studies are considered from the standpoint of relationship to several areas of research on Rhizobium.

Alkylated derivatives of poly(ethylacrylic acid) can be inserted into preformed liposomes and trigger pH-dependent intracellular delivery of liposomal contents

2004 ◽  
Vol 21 (6) ◽  
pp. 385-393 ◽  
Author(s):  
Tao Chen ◽  
Deirdre Mcintosh ◽  
Yuehua He ◽  
Jungsoo Kim ◽  
David A. Tirrell ◽  
...  
Keyword(s):  
Intracellular Delivery ◽  
Ph Dependent ◽  
Derivatives Of

Preparation of bisulphite addition compounds of 5-Amino-5-deoxy-D-xylose

1966 ◽  
Vol 19 (4) ◽  
pp. 667 ◽  
Author(s):  
DL Ingles
Keyword(s):  
Amino Acid ◽  
Free Amino ◽  
Amino Sugar ◽  
Barium Hydroxide ◽  
Free Sugar ◽  
Amino Sugars ◽  
Addition Compound ◽  
Derivatives Of

Sulphurous acid alone and in admixture with other stronger acids has been used to hydrolyse 5-amino, 5-N-cyclohexylamino, and 5-N-piperidino derivatives of 5-deoxy-l,2-O-isopropylidene-D-xylose. The bisulphite addition compounds of the corresponding amino sugars were thus isolated. Similarly, methyl 5-amino-5-deoxy- 2,3-O-isopropylidene-D-riboside was hydrolysed to yield the bisulphite addition compound of 5-amino-5-deoxy-D-ribose. Treatment of the bisulphite addition compound of 5-amino-5-deoxy-D-xylose with barium hydroxide gave the free amino sugar as a syrup in 96% yield. Removal of bisulphite from the addition compound of 5-X-cyclohexylamino-5-deoxy-D-xylose gave the free sugar in 30% yield together with an amino acid (XVI).

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