Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tryptophanase”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1975

Metabolism of cyclic adenosine 3',5'-monophosphate and induction of tryptophanase in Escherichia coli.

The relationship between cyclic adenosine 3',5'-monophosphate (cyclic AMP) metabolism and the induction of tryptophanase and beta-galactosidase was studied in several strains of Escherichia coli grown with succinate, acetate, glycerol, or glucose as the carbon source. No consistent relationship between the intracellular concentration of cyclic AMP in the several strains cultured and the various carbon sources was discerned. In E. coli K-12-1 the induction of tryptophanase was found to vary in the order: succinate greater than acetate greater than glycerol greater than glucose, and that of beta-galactosidase was found in the order: glycerol greater than acetate greater than succinate greater than glucose. Rate of accumulation of cyclic AMP in the culture filtrate was in the order: succinate greater than acetate greater than glycerol greater than glucose. The addition of glycerol to E. coli K-12-1 grown in acetate caused inhibition of tryptophanase and slight inhibition of accumulation of extracellular cyclic AMP. These same conditions caused beta-galactosidase induction to be stimulated. The addition of exogenous cyclic AMP to cultures grown with four different carbon sources had an effect characteristic for each of the two enzymes studied as well as each individual carbon source. The results suggest that there are control elements distinct from cyclic AMP and its receptor protein which respond to the catabolic situation of the cell.

Acetates↗
PubMed1977

Unstable mutations that relieve catabolite repression of tryptophanase synthesis by Escherichia coli.

From strains of Escherichia coli that carry deletions of the trp region, five different mutants were isolated that were capable of synthesizing tryptophanase at unusually high rates in conditions of severe catabolite repression. Notwithstanding the comparative insensitivity to catabolite repression, the rates of tryptophanase synthesis in the mutants were greatly diminished by the introduction of a defective gene for adenyl cyclase. Each of the mutants segregated variants of the parental type. The results of genetic analysis appear to be consistent with the mutants arose by duplication of the tryptophanase gene.

Adenylyl Cyclases↗
PubMed1962

Tryptophanase-tryptophan synthetase systems in Escherichia coli. I. Effect of tryptophan and related compounds.

Freundlich, Martin (University of Minnesota, Minneapolis) and Herman C. Lichstein. Tryptophanase-tryptophan synthetase systems in Escherichia coli. I. Effect of tryptophan and related compounds. J. Bacteriol. 84:979-987. 1962.-The effect of tryptophan and related compounds on tryptophanase and tryptophan synthetase formation in Escherichia coli was determined. Several of these compounds stimulated the formation of tryptophanase while concomitantly decreasing the production of synthetase. A number of tryptophan analogues were found to inhibit growth. The possible mode of action of these substances was examined further. 5-Hydroxytryptophan greatly inhibited the formation of synthetase and also reduced growth. Its inhibitory action on growth was attributed, at least partially, to the false feedback inhibition of anthranilic acid formation. Tryptamine was found to be a potent inhibitor of the activity of synthetase, as well as of the enzyme(s) involved in the synthesis of anthranilic acid from shikimic acid. However, growth reduction was only partially reversed by tryptophan. Indole-3-acetic acid and indole-3-propionic acid decreased growth and increased the formation of synthetase six- to eightfold. The action of these compounds was ascribed to their ability to block the endogenous formation of tryptophan.

Escherichia coli↗
PubMed2002

Isolation of an Escherichia coil strain mutant unable to form biofilm on polystyrene and to adhere to human pneumocyte cells: involvement of tryptophanase.

Escherichia coli adherence to biotic and abiotic surfaces constitutes the first step of infection by promoting colonization and biofilm formation. The aim of this study was to gain a better understanding of the relationship between E. coli adherence to different biotic surfaces and biofilm formation on abiotic surfaces. We isolated mutants defective in A549 pneumocyte cells adherence, fibronectin adherence, and biofilm formation by random transposition mutagenesis and sequential passages over A549 cell monolayers. Among the 97 mutants tested, 80 were decreased in biofilm formation, 8 were decreased in A549 cells adherence, 7 were decreased in their adherence to fibronectin, and 17 had no perturbations in either of the three phenotypes. We observed a correlation between adherence to fibronectin or A549 cells and biofilm formation, indicating that biotic adhesive factors are involved in biofilm formation by E. coli. Molecular analysis of the mutants revealed that a transposon insertion in the tnaA gene encoding for tryptophanase was associated with a decrease in both A549 cells adherence and biofilm formation by E. coli. The complementation of the tnaA mutant with plasmid-located wild-type tnaA restored the tryptophanase activity, epithelial cells adherence, and biofilm formation on polystyrene. The possible mechanism of tryptophanase involvement in E. coli adherence and biofilm formation is discussed.

Bacterial Adhesion↗
PubMed1975

Substrate-protein interaction in tryptophanase from Bacillus alvei. Kinetic and spectral evaluations.

This investigation studied the substrate protein interaction of the alpha, beta elimination reaction in tryptophanase (EC 4.1.99.1). The results of this work are 2-fold. (a) The presence of multiple enzyme sites was found to be related to the observed kinetic patterns of inhibition. Indole analogues caused competitive inhibition in the tryptophanase reaction and noncompetitive inhibition in the dehydratase reaction. Inhibition patterns of alanine for these activities were reserved. (b) Under some conditions, compounds which bind presumably at the indole site modified the spectral and fluorescent characteristics of the enzyme. The addition of anthranilate to the enzyme resulted in a broad absorption band around 350 nm. This absorption band was distinct from that formed by alanine addition. Based on absorption data, both of these compounds could be bound simultaneously. The optical activity of tryptophanase was reported for the first time. Indole analogues caused greater conformational alterations in the circular dichroism spectra than 3-carbon analogues. The calculated anisotrophy factors, as well as fluorescent quenching data, suggest a more direct interaction between indole analogues and pyridoxal-P than between 3-carbon compounds that the coenzyme. It is proposed that the indole site is the dominant recognition site. The data are consistent with the three-dimensional aspects of space-filling models of Schiff's bases evaluated in terms of multiple site binding.

Amino Acids↗
PubMed1992

Characterization of the tryptophanase operon of Proteus vulgaris. Cloning, nucleotide sequence, amino acid homology, and in vitro synthesis of the leader peptide and regulatory analysis.

The tryptophanase (tna) operon of Proteus vulgaris was cloned and characterized and found to be organized similarly to the tna operon of Escherichia coli. Both operons contain two major structural genes, tnaA and tnaB, that encode tryptophanase and a tryptophan permease, respectively. tnaA of P. vulgaris is preceded by a transcribed leader region, encoding a 34-residue leader peptide, TnaC, that contains a single tryptophan residue. The tnaC coding region also has a boxA-like sequence. Regulatory studies performed in P. vulgaris, and with a plasmid carrying the P. vulgaris tna operon in E. coli, established that expression of the Proteus operon was induced by tryptophan and was subject to catabolite repression. Site-directed mutagenesis studies established that translation of the tnaC coding region was essential for induction. Synthesis of the P. vulgaris leader peptide was demonstrated in an in vitro coupled transcription-translation system. Interestingly, the 5 amino acid residues of the TnaC peptide surrounding the sole tryptophan residue are identical in P. vulgaris and E. coli. We conclude that the tna operon of P. vulgaris is also regulated by tryptophan-induced transcription antitermination. Homology of tryptophanase and tryptophan permease of P. vulgaris to related proteins from other species is described.

Amino Acid Sequence↗
PubMed1991

Equilibria and absorption spectra of tryptophanase.

Tryptophanase (tryptophan: indole-lyase) from Escherichia coli has been isolated in the holoenzyme form and its absorption spectra and acid-base chemistry have been reevaluated. Apoenzyme has been prepared by dialysis against sodium phosphate and L-alanine and molar absorptivities of the coenzyme bands have been estimated by readdition of pyridoxal 5'-phosphate. The spectrophotometric titration curve, whose midpoint is at pH 7.6 in 0.1 M potassium phosphate buffers, indicates some degree of cooperativity in dissociation of a pair of protons. Resolution of the computed spectra of individual ionic forms of the enzyme with lognormal distribution curves shows that band shapes are similar to those of model Schiff bases and of aspartate aminotransferase. Using molar areas from the latter we estimated amounts of individual tautomeric species. In addition to ketoenamine and enolimine or covalent adduct the high pH form also appears to contain approximately 18% of a species with a dipolar ionic ring (protonated on the ring nitrogen and with phenolate -O-). We suggest that this may be the catalytically active form of the coenzyme in tryptophanase. The equilibrium between tryptophanase and L-alanine has also been reevaluated.

Escherichia coli↗
PubMed1985

Tryptophanase activity in different toxigenic and nontoxigenic strains of Vibrio cholerae: effect of glucose.

Tryptophanase activity was measured in eight different toxigenic and nontoxigenic strains of Vibrio cholerae (V. cholerae) in presence and absence of inducer tryptophan (2 mM). Stimulation of enzyme activity was observed in both toxigenic and nontoxigenic strains of V. cholerae in presence of inducer. Tryptophanase activity remained much higher in toxigenic strains than that in nontoxigenic strains. Low levels of enzyme activity in nontoxigenic strains could be increased by the addition of exogenous cyclic AMP. A lower concentration of glucose (0.25 gm%) in culture medium produced no inhibitory effect on enzyme activity. But a higher concentration of glucose (3 gm%) repressed the tryptophanase activity. The repressive effect of glucose could be reversed by the addition of exogenous cyclic AMP.

Cyclic AMP↗
PubMedDate not supplied

[Interaction of tryptophanase with substrate analogs].

Tryptophanase from Escherichia coli was studied with respect to its interactions with L-alanine, beta-chloro-L-alanine, L-phenylalanine, L-methionine, L-threonine, beta-phenyl-DL-serine (threo form) and also with a new tryptophan analog oxindolyl-L-alanine. Slow transamination of L-alanine in the active site of the enzyme was observed. Some evidence is presented which indicates that the side transamination reaction occurs during incubation of tryptophanase with an adequate substrate, beta-chloro-L-alanine. Absorption and circular dichroism (CD) spectra of the enzyme-quasisubstrate complexes have been recorded. Addition of beta-phenylserine and threonine to the enzyme induces a decrease of absorbance at 337 nm and an increase of absorbance at 420 nm. The spectral changes are associated with inversion of the CD sign, i.e. with disappearance of positive CD in the 420 nm band and appearance of negative CD in this band. It is inferred that beta-phenylserine and threonine form an external coenzyme-substrate aldimine which undergoes slow conversion to give a keto acid and the free enzyme. Addition of oxindolylalanine to tryptophanase results in the formation of an intense narrow absorption band at 504 nm with a shoulder at about 475 nm. This band belongs to a quinonoid intermediate. A positive CD is seen in the 504 nm band; the dissymmetry factor (delta A/A) in this band is much smaller than that in the absorption bands of the free enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Circular Dichroism↗
PubMed1985

Differential inhibition of tryptophan synthase and of tryptophanase by the two diastereoisomers of 2,3-dihydro-L-tryptophan. Implications for the stereochemistry of the reaction intermediates.

Oxindolyl-L-alanine and 2,3-dihydro-L-tryptophan, which are analogs of a proposed reaction intermediate, are potent competitive inhibitors of both tryptophanase and the alpha 2 beta 2 complex of tryptophan synthase (Phillips, R. S., Miles, E. W., and Cohen, L. A. (1984) Biochemistry 23, 6228-6234). Since these inhibitors can exist in two diastereoisomeric forms, which we expected to differ in inhibitory potency, we have separated the diastereoisomers of 2,3-dihydro-L-tryptophan by preparative high performance liquid chromatography. These diastereoisomers were designated "A" and "B" in order of elution from the high performance liquid chromatography column. Diastereoisomer B is a potent competitive inhibitor of the alpha 2 beta 2 complex of tryptophan synthase with KI = 6 microM at pH 7.8 and 25 degrees C. In contrast, diastereoisomer A is a weak competitive inhibitor, with KI = 940 microM under these conditions. With tryptophanase, the situation is reversed; diastereoisomer A is a potent slow-binding competitive inhibitor of tryptophanase with KI = 2 microM at pH 8.0 and 25 degrees C, while diastereoisomer B is much weaker with KI = 1600 microM under these conditions. These results not only provide additional support for the proposal that the indolenine tautomer of tryptophan is an intermediate in the reactions catalyzed by both enzymes but also suggest that these enzymes catalyze their respective reactions via enantiomeric indolenine intermediates.

Chromatography, High Pressure Liquid↗
PubMed1994

Tryptophanase from Escherichia coli: catalytic and spectral properties in water-organic solvents.

In water-methanol and water-dimethylformamide (DMF) (1:1 v/v) solutions tryptophanase from E.coli retains its abilities to form a quinonoid complex with quasisubstrates and to catalyze the decomposition of S-o-nitrophenyl-L-cysteine (SOPC). Both the KM and Vmax values decrease in water-organic media. The affinities of tryptophanase for L-alanine, L-tryptophan, oxindolyl-L-alanine and indole in aqueous methanol are decreased, the effect being stronger for the more hydrophobic substances. In a water solution tryptophanase catalizes the reaction of SOPC with indole to form L-tryptophan while in water-organic solvents only decomposition of SOPC is observed.

Alanine↗
PubMed2004

Kinetics of L-tryptophan production from indole and L-serine catalyzed by whole cells with tryptophanase activity.

The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by whole cells of Escherichia coli B1t-7A with tryptophanase activity. The reaction was previously studied using soluble tryptophanase, a kinetic mechanism proposed and the catalytic properties of the enzyme described. It is important, however, to determine the kinetic parameters of the reaction catalyzed by whole cells, if the process is to be designed with the catalyst in this form. The reaction stoichiometry was established, a mole of product being formed from a mole of each reactant, with no indication of side reactions under the conditions used. The two-substrate reaction kinetics were characterized and modelled, assuming an enzyme-substituted mechanism and no product inhibition. Theoretical consumption rates of indole were compared with experimental values obtained in a batch reactor system. The K(m) values of whole cells towards L-serine and indole were 1.79 M and 0.07 M, respectively. These values are, as expected, considerably higher than their counterparts for soluble tryptophanase.

Journal Article↗
PubMed1972

Reversibility of the tryptophanase reaction: synthesis of tryptophan from indole, pyruvate, and ammonia.

Degradation of tryptophan to indole, pyruvate, and ammonia by tryptophanase (EC 4....) from Escherichia coli, previously thought to be an irreversible reaction, is readily reversible at high concentrations of pyruvate and ammonia. Tryptophan and certain of its analogues, e.g., 5-hydroxytryptophan, can be synthesized by this reaction from pyruvate, ammonia, and indole or an appropriate derivative at maximum velocities approaching those of the degradative reactions. Concentrations of ammonia required for the synthetic reactions produce specific changes in the spectrum of tryptophanase that differ from those produced by K(+) and indicate that ammonia interacts with bound pyridoxal 5'-phosphate to form an imine. Kinetic results indicate that pyruvate is the second substrate bound, hence indole must be the third. These results favor a modified mechanism for the multitude of tryptophanase-catalyzed reactions in which alpha-aminoacrylate, which functions as a common enzyme-bound intermediate in both synthetic and degradative reactions, is not released into the medium during the latter reactions, but is degraded to pyruvate and ammonia by sequential reversible steps via enzyme-bound intermediates.

Acrylates↗
PubMed1962

Tryptophanase-tryptophan synthetase systems in Escherichia coli. III. Requirements for enzyne synthesis.

Freundlich, Martin (University of Minnesota, Minneapolis) and Herman C. Lichstein. Tryptophanase-tryptophan synthetase systems in Escherichia coli. III. Requirements for enzyme synthesis. J. Bacteriol. 84:996-1006. 1962.-The requirements for the formation of tryptophanase and tryptophan synthetase in Escherichia coli during repression release were studied. The kinetics of the formation of tryptophan synthetase differed in the two strains examined; this was attributed to differences in the endogenous level of tryptophan in the bacterial cells. The formation of both enzymes was inhibited by chloramphenicol, and by the absence of arginine in an arginine-requiring mutant. These results are indicative of a requirement for protein synthesis for enzyme formation. Requirements for nucleic acid synthesis were examined by use of a uracil- and thymine-requiring mutant, and with purine and pyrimidine analogues. The results obtained suggest that some type of ribonucleic acid synthesis was necessary for the formation of tryptophanase and tryptophan synthetase.

Chloramphenicol↗
PubMed1965

GENETIC ANALYSIS OF TRYPTOPHANASE MUTANTS OF ESCHERICHIA COLI.

Gartner, Theodore K. (University of California, Davis), and Monica Riley. Genetic analysis of tryptophanase mutants of Escherichia coli. J. Bacteriol. 89:319-325. 1965.-The tryptophanase structural gene tna, and one of the tryptophanase regulation genes, R(1)tna, are closely linked, and lie between the pyr-E and ilv genes on the Escherichia coli chromosome. The mutant form of the regulation gene, which confers the properties of inducibility at 13 C, constitutivity at 37 C, and hyperinducibility at 37 C, is dominant over the wild form of the gene. Another regulation gene, R(2)tna, confers constitutivity at 13 C and does not map at the same locus as the R(2)tna gene.

Escherichia coli↗
PubMed1978

Effect of guanosine 5'-diphosphate 3'-diphosphate and related nucleoside polyphosphates on induction of tryptophanase and beta-galactosidase in permeabilized cells of Escherichia coli.

Exogenous addition of guanosine and adenosine 5'-(mono, di and tri) phosphate 3'-diphosphates (pppGpp, ppGpp, pGpp, pppApp, ppApp and pApp) stimulated the synthesis of tryptophanase and beta-galactosidase in permeabilized cells of Escherichia coli. From the results obtained with ppGpp and pppApp, this effect appeared to be at a transcriptional level and depended greatly on the growth condition; the largest effect was observed in cells under shiftdown or grown on poor enrgy source. ppGpp and pppApp, unlike cyclic AMP, did not act to overcome the inhibition of enzyme induction by glucose, but in combination with cyclic AMP caused a synergistic stimulation effect. In the shiftdown cells, ppGpp and pppApp gave 30% or more stimulation effect on tryptophanase induction while cyclic AMP did not stimulate induction. There was therefore a pronounced difference between cyclic AMP and ppGpp or pppApp in stimulatory function.

Adenine Nucleotides↗
PubMed1977

Simultaneous and successive induction of synthesis of beta-galactosidase and tryptophanase in Escherichia coli K 12 in the chemostat.

beta-Galactosidase and tryptophanase were induced either simultaneously or successively during continuous cultivation of the inducible strain Escherichia coli K 12 in the chemostat. Growth was limited by glycerol and the dilution rate was 0.1 h-1. During both the simultaneous and successive induction specific rates of synthesis, as well as maximum enzyme levels, were identical with those obtained after independent induction of individual enzymes. As compared with batch cultivation, beta-galactosidase reached the same specific rate of synthesis in the chemostat, whereas the specific rate of synthesis of tryptophanase in the chemostat was up to five times higher.

Bacteriological Techniques↗