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PubMed1981

Molecular complex of lumiflavin and 2-aminobenzoic acid: crystal structure, crystal spectra, and solution properties.

The molecular complex lumiflavin-2-aminobenzoic acid monohydrate (C13H12N4O2.C7H7NO2.H2O) crystallizes from from aqueous solution as red triclinic prisms. The space group is P1 with cell dimensions a = 9.660 A, b = 14.866 A, c = 7.045 A, alpha = 95.44 degrees , beta = 95.86 degrees, and gamma = 105.66 degrees . The crystal structure was solved by direct methods and refined by block-diagonal least-squares procedures to an R value of 0.050 on the basis of 1338 observed reflections. The structure is composed of stacks of alternating lumiflavin adn un-ionized (neutral) 2-aminobenzoic acid molecules. Two different modes of stacking interaction are observed. In one, 2-aminobenzoic acid overlaps all three of the isoalloxazine rings, at a mean distance of 3.36 A; in the other, 2-aminobenzoic acid interacts distance of 3.36 A; in the other, 2-aminobenzoic acid interacts with the pyrazine and dimethylbenzene moieties, at a distance of 3.42 A. Perpendicular to the stacking direction, the molecules form a continuous sheet. Each flavin is hydrogen bonded via O(2) and NH(3) to two symmetrically related aminobenzoates; the water of crystallization forms three hydrogen bonds, bridging two flavins, via O(4) and N(5), and one aminobenzoic acid. The red color of the crystals results from a charge-transfer transition involving stacked flavin and 2-aminobenzoic acid. The red color of the crystals results from a charge-transfer transition involving stacked flavin and 2-aminobenzoic acid molecules. Measurements of the polarized optical absorption spectra of crystals show that the transition moment direction for the long wavelength absorbance (beyond 530 nm) contains an out-of-plane component which can only arise from a charge-transfer interaction. Since the amino N does not make exceptionally close interactions with isoalloxazine atoms in either stacking mode (minimum interatomic distance 3.52 A), the charge transfer is presumed to involve pi orbitals of the 2-aminobenzoic acid donor.

Chemical Phenomena↗
PubMed1991

Purification and characterization of benzoate-coenzyme A ligase and 2-aminobenzoate-coenzyme A ligases from a denitrifying Pseudomonas sp.

The enzymes catalyzing the formation of coenzyme A (CoA) thioesters of benzoate and 2-aminobenzoate were studied in a denitrifying Pseudomonas sp. anaerobically grown with these aromatic acids and nitrate as sole carbon and energy sources. Three different rather specific aromatic acyl-CoA ligases, E1, E2, and E3, were found which catalyze the formation of CoA thioesters of benzoate, fluorobenzoates, and 2-aminobenzoate. ATP is cleaved into AMP and pyrophosphate. The enzymes were purified, their N-terminal amino acid sequences were determined, and their catalytic and molecular properties were studied. Cells anaerobically grown on benzoate and nitrate contain one CoA ligase (AMP forming) for benzoic acid (E1). It is a homodimer of Mr 120,000 which prefers benzoate as a substrate but shows some activity also with 2-aminobenzoate and fluorobenzoates, although with lower Km. Cells anaerobically grown on 2-aminobenzoate and nitrate contain three different CoA ligases for aromatic acids. The first one is identical with benzoate-CoA ligase (E1). The second enzyme is a 2-aminobenzoate-CoA ligase (E2). It is a monomer of Mr 60,000 which prefers 2-aminobenzoate but also activates benzoate, fluorobenzoates and, less effectively, 2-methylbenzoate, with lower affinities to the latter substrates. The enzymes E1 and E2 have similar activity levels; a third minor CoA ligase activity is due to a different 2-aminobenzoate-CoA ligase. The enzyme (E3) is a monomer of Mr, 65,000 which 2-aminobenzoate pathway (U. Altenschmidt, C. Eckerskorn, and G. Fuchs, Eur. J. Biochem. 194:647-653, 1990); apparently, it is not completely repressed under anaerobic conditions and therefore also is induced to a small extent by 2-aminobenzoate under anaerobic growth conditions.

Amino Acid Sequence↗
PubMed1995

Activity of p-aminobenzoic acid compared with other organic acids against selected bacteria.

The antibacterial activity of p-aminobenzoic acid against Listeria monocytogenes, Salmonella enteritidis and Escherichia coli was compared with the activity of commonly used acidulants: formic, propionic, acetic, lactic and citric acids. Viable count evaluations and MIC determinations indicated that p-aminobenzoic acid caused greater inhibitory effects than the other organic acids. The activity of p-aminobenzoic acid on the growth of the test organisms at selected pH values indicated that p-aminobenzoic acid was more active at low pH than at high pH. Uptake studies showed that the uptake of p-aminobenzoic acid by E. coli was markedly decreased as the pH values increased. Electron micrographs of E. coli cells grown in the presence of p-aminobenzoic acid indicate that p-aminobenzoic acid caused marked damage to the cell envelope. It is suggested that p-aminobenzoic acid has at least two mechanisms of action: one mechanism in common with other organic acids and the other mechanism by interfering with the synthesis of the peptidoglycan layer by an action on the dihydrofolate reductase enzyme.

4-Aminobenzoic Acid↗
PubMed1992

Anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) via benzoyl-coenzyme A (CoA) and cyclohex-1-enecarboxyl-CoA in a denitrifying bacterium.

The enzymes catalyzing the initial reactions in the anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) were studied with a denitrifying Pseudomonas sp. anaerobically grown with 2-aminobenzoate and nitrate as the sole carbon and energy sources. Cells grown on 2-aminobenzoate are simultaneously adapted to growth with benzoate, whereas cells grown on benzoate degrade 2-aminobenzoate several times less efficiently than benzoate. Evidence for a new reductive pathway of aromatic metabolism and for four enzymes catalyzing the initial steps is presented. The organism contains 2-aminobenzoate-coenzyme A ligase (2-aminobenzoate-CoA ligase), which forms 2-aminobenzoyl-CoA. 2-Aminobenzoyl-CoA is then reductively deaminated to benzoyl-CoA by an oxygen-sensitive enzyme, 2-aminobenzoyl-CoA reductase (deaminating), which requires a low potential reductant [Ti(III)]. The specific activity is 15 nmol of 2-aminobenzoyl-CoA reduced min-1 mg-1 of protein at an optimal pH of 7. The two enzymes are induced by the substrate under anaerobic conditions only. Benzoyl-CoA is further converted in vitro by reduction with Ti(III) to six products; the same products are formed when benzoyl-CoA or 2-aminobenzoyl-CoA is incubated under reducing conditions. Two of them were identified preliminarily. One product is cyclohex-1-enecarboxyl-CoA, the other is trans-2-hydroxycyclohexane-carboxyl-CoA. The complex transformation of benzoyl-CoA is ascribed to at least two enzymes, benzoyl-CoA reductase (aromatic ring reducing) and cyclohex-1-enecarboxyl-CoA hydratase. The reduction of benzoyl-CoA to alicyclic compounds is catalyzed by extracts from cells grown anaerobically on either 2-aminobenzoate or benzoate at almost the same rate (10 to 15 nmol min-1 mg-1 of protein). In contrast, extracts from cells grown anaerobically on acetate or grown aerobically on benzoate or 2-aminobenzoate are inactive. This suggests a sequential induction of the enzymes.

Acyl Coenzyme A↗
PubMed1998

Reversed-phase high-performance liquid chromatographic measurement of the P-aminobenzoic acid synthesized by Streptococcus sanguis.

OBJECTIVE: This study investigated the biosynthesis of P-aminobenzoic acid by Streptococcus sanguis and the role of P-aminobenzoic acid in the interaction between Streptococcus sanguis and Streptococcus mutans. METHODS: A reversed-phase high-performance liquid chromatographic technique was used to analyze the P-aminobenzoic acid synthesized by Streptococcus sanguis in an anaerobic atmosphere. RESULTS: The results showed, that (1) the chromatographic method established in this study had good linear relation and the average recovery of P-aminobenzoic acid was 80%, and (2) Streptococcus sanguis did synthesize P-aminobenzoic acid, and the mean concentration of P-aminobenzoic acid was 1.23 micrograms/mL. CONCLUSIONS: The results of this study will help further studies of the factors that may have effects on P-aminobenzoic acid synthesis by Streptococcus sanguis and on the role of P-aminobenzoic acid in the microbial homeostasis of dental plaque.

4-Aminobenzoic Acid↗
PubMed1981

Studies on the absorption of the pancreatic function test peptide, N-benzoyl-L-tyrosyl-p-aminobenzoic acid, and related compounds by isolated rat small intestine.

The peptide, N-benzoyl-L-tyrosyl-p-aminobenzoic acid, which is used in an oral test of pancreatic function, has been perfused through isolated rat small intestine in order to determine whether it can be absorbed across the intestine in intact form, and whether it is hydrolysed appreciably by intestinal enzymes. For comparison, transport of N-benzoyl-DL-tyrosine, L-tyrosine, L-tyrosyl-L-leucine and p-aminobenzoic acid has also been studied. Very small amounts of bound tyrosine (probably mainly intact peptide plus some benzoyl-tyrosine) and of free p-aminobenzoic acid crossed the intestine during perfusion with N-benzoyl-L-tyrosyl-p-aminobenzoic acid. Adsorbed pancreatic enzymes were possibly responsible for the very small amount of hydrolysis of the peptide. However, no detectable free tyrosine crossed the intestine during perfusion with N-benzoyl-L-tyrosyl-p-aminobenzoic acid or with N-benzoyl-DL-tyrosine. In contrast, substantial quantities of free tyrosine crossed the intestine during perfusion with L-tyrosine or with L-tyrosyl-L-leucine. Net transport of tyrosine from L-tyrosyl-L-leucine was less than that from equimolar free L-tyrosine; no detectable intact L-tyrosyl-L-leucine crossed the intestine. During perfusion with free p-aminobenzoic acid the concentration in the serosal secretion apparently exceeded that in the lumen by a factor of 1.7; this suggests active transport of p-aminobenzoic acid.

4-Aminobenzoic Acid↗
PubMed1991

The bentiromide test using plasma p-aminobenzoic acid for diagnosing pancreatic insufficiency in young children. The effect of two different doses and a liquid meal.

The bentiromide test was evaluated using plasma p-aminobenzoic acid as an indirect test of pancreatic insufficiency in young children between 2 months and 4 years of age. To determine the optimal test method, the following were examined: (a) the best dose of bentiromide (15 mg/kg or 30 mg/kg); (b) the optimal sampling time for plasma p-aminobenzoic acid; and (c) the effect of coadministration of a liquid meal. Sixty-nine children 91.6 +/- 1.0 years) were studied, including 34 controls with normal fat absorption and 35 patients (34 with cystic fibrosis) with fat maldigestion due to pancreatic insufficiency. Control and pancreatic insufficient subjects were studied in three age-matched groups: (a) low-dose bentiromide (15 mg/kg) with clear fluids; (b) high-dose bentiromide (30 mg/kg) with clear fluids; and (c) high-dose bentiromide with a liquid meal. Plasma p-aminobenzoic acid was determined at 0, 30, 60, and 90 minutes then hourly for 6 hours. The dose effect of bentiromide with clear liquids was evaluated. High-dose bentiromide best discriminated control and pancreatic insufficient subjects, due to a higher peak plasma p-aminobenzoic acid level in controls, but poor sensitivity and specificity remained. High-dose bentiromide with a liquid meal produced a delayed increase in plasma p-aminobenzoic acid in the control subjects probably caused by retarded gastric emptying. However, in the pancreatic insufficient subjects, use of a liquid meal resulted in significantly lower plasma p-aminobenzoic acid levels at all time points; plasma p-aminobenzoic acid at 2 and 3 hours completely discriminated between control and pancreatic insufficient patients. Evaluation of the data by area under the time-concentration curve failed to improve test results. In conclusion, the bentiromide test is a simple, clinically useful means of detecting pancreatic insufficiency in young children, but a higher dose administered with a liquid meal is recommended.

4-Aminobenzoic Acid↗
PubMed1975

Purification of Escherichia coli B-specific p-aminobenzoate "pick-up" protein to homogeneity by affinity chromatography.

Of the satellite fractions of Escherichia coli B dihydrofolate synthetases, a non-enzymic protein that is specifically able to bind p-aminobenzoate and sulphonamides has been purified 6000-fold by p-aminobenzoylcellulose affinity chromatography. The protein was named p-aminobenzoate "pick-up" protein according to its function, i.e., to bring p-aminobenzoate into reaction with L-glutamate and pteridine during dihydrofolate biosynthesis. About 4 mg of pure protein (0.532% recovery, calculated from the total p-aminobenzoate binding capacity of the unfractionated supernatant separated from the crude bacterium plasma) can be obtained from 500 g of harvested cells. The product is homogeneous in polyacrylamide gel electrophoresis both in the absence and presence of sodium dodecyl sulphate, and has a molecular weight of 15,000 daltons +/- 5% as measured by sodium dodecyl sulphate gel electrophoresis and Sephadex G-75 gel column chromatography. p-Aminobenzoate and sulphonamide ligand binding studies showed a single binding site per p-aminobenzoate pick-up protein molecule. KD values for p-aminobenzoate and some sulphonamides as well as for L-glutamate, L-gamma-glutamyl oligopeptides, some pteridines and folate antagonists are also presented in order to illustrate the specificity of the receptor protein.

Aminobenzoates↗
PubMed2003

A prospective, comparative study of the para-aminobenzoic acid test and faecal elastase 1 in the assessment of exocrine pancreatic function.

BACKGROUND: The assessment of exocrine pancreatic insufficiency is part of the routine work-up of patients with persistent diarrhoea or suspected steatorrhoea. Direct and indirect tests for the diagnosis of exocrine pancreatic insufficiency have their drawbacks. Measurement of faecal elastase 1 by enzyme-linked immunoabsorbent assay is a simple, non-invasive, robust test for exocrine pancreatic insufficiency. METHODS: We performed a prospective comparison of the para-aminobenzoic acid test and faecal elastase 1 test in 45 patients being investigated for diarrhoea or suspected steatorrhoea. Details of clinical suspicion, imaging and response to treatment were recorded. RESULTS: Exocrine pancreatic function was normal in 20 patients with normal para-aminobenzoic acid and faecal elastase 1 levels. Eight patients had exocrine pancreatic insufficiency with low para-aminobenzoic acid and faecal elastase 1 levels, which improved with enzyme supplementation. In 14 of the 15 patients with low or borderline low para-aminobenzoic acid and normal faecal elastase 1 levels, a non-pancreatic cause was found; one patient had a false positive para-aminobenzoic acid test. Two had normal para-aminobenzoic acid but low faecal elastase 1 levels. One improved with pancreatic supplementation, and imaging revealed chronic pancreatitis. The other had a false positive faecal elastase 1 test related to profuse diarrhoea. CONCLUSIONS: Faecal elastase 1 estimation is a simple, non-invasive, robust test of exocrine pancreatic insufficiency, performed on an out-patient stool sample. Its diagnostic performance is superior to that of the para-aminobenzoic acid test in investigating patients with diarrhoea or suspected steatorrhoea.

4-Aminobenzoic Acid↗
PubMed1980

The oral pancreatic function test with N-benzoyl-L-tyrosyl-p-aminobenzoic acid: acute toxicity and effects of renal function on this test.

The oral pancreatic function test with N-benzoyl-L-tyrosyl-p-aminobenzoic acid was performed on 24 healthy test subjects, and its toxicity was examined. Eight patients with restricted renal function and known renal disease were also investigated. The pancreatic function test and the same procedure using free p-amino-benzoic acid were performed at 2-3-day intervals. During all the investigations with the pancreatic function test, no clinical side effects were observed. All parameters investigated at all the test times fell within the normal range. No toxicity of N-benzoyl-L-tyrosyl-p-amino-benzoic acid could be found. The excretion of p-aminobenzoic acid after administration of N-benzoyl-L-tyrosyl-p-aminobenzoic acid ws greatly reduced in all patients with restricted renal function. Four of eight patients also showed essentially no increase in excretion rate when free p-aminobenzoic acid was given instead of the peptide. It is therefore not possible to correct the pancreatic function test results in patients with renal insufficiency by calculating the ratio of p-aminobenzoic acid excretion after peptide intake to that after free p-aminobenzoic acid ingestion. Adequate renal function is therefore a prerequisite for the pancreatic function test.

4-Aminobenzoic Acid↗
PubMed1986

Potassium para-aminobenzoate and liver function test findings.

Risk of hepatotoxicity has been raised with respect to potassium para-aminobenzoate (Potaba) therapy. In this regard relevant clinical and laboratory hepatic findings in the hospital records of 390 scleroderma patients were analyzed. There were 274 patients who had received potassium para-aminobenzoate at some time and 116 who never received it. No instance was found in which potassium para-aminobenzoate was the cause of an acute hepatic hypersensitivity reaction. There were random or intercurrent abnormalities in hepatic test findings over time, but these actually occurred more often in the group of patients never treated with potassium para-aminobenzoate. Further, there was no evidence that long-term potassium para-aminobenzoate therapy is hepatotoxic. These findings suggest that acute hepatic reaction to potassium para-aminobenzoate is at least uncommon if not rare.

4-Aminobenzoic Acid↗
PubMed1994

Aerobic biodegradation of 3-aminobenzoate by gram-negative bacteria involves intermediate formation of 5-aminosalicylate as ring-cleavage substrate.

The aerobic metabolism of 3-aminobenzoate by bacteria was studied. Bacterial strains degrading 3-aminobenzoate were obtained by enrichment with 3-aminobenzoate (strain Ia3) or 5-aminosalicylate (strains BN9 and 5AS1). During growth with 3-aminobenzoate, strain Ia3 and strain 5AS1 transiently accumulated 5-aminosalicylate in the culture broth. In the presence of inhibitors of 5-aminosalicylate 1,2-dioxygenase, resting cells of all three strains converted 3-aminobenzoate to stoichiometric amounts of 5-aminosalicylate. 5-Aminosalicylate 1,2-dioxygenase activity was induced in all strains after growth with 3-aminobenzoate or 5-aminosalicylate, but not after growth in complex media.

Aminobenzoates↗