Formation of 2-methyl-2,4-thiazolidinedicarboxylic acid from L-cysteine in rat tissues.

The adduct formed non-enzymatically from L-cysteine and pyruvate: 2-methyl-2,4-thiazolidinecarboxylic acid (CP) was isolated, and identified by the electron impact mass spectroscopy. It was found that CP is formed (by cysteine transformation) and is metabolized in rat tissues. Formation of CP from cysteine or cystine was catalysed by partially purified rat liver gamma-cystathionase.

Myxothiazol, an antibiotic from Myxococcus fulvus (myxobacterales). I. Cultivation, isolation, physico-chemical and biological properties.

Myxothiazol (AB-Mx f16-1), a new antifungal antibiotic, is produced by the myxobacterium Myxococcus fulvus strain Mx f16. It is active against many filamentous fungi, and completely inhibits growth of Mucor hiemalis at a concentration of 2 micrograms/ml. The molecular formula of myxothiazol was determined to e C25H33N3O3S2.

Karnamicin, a complex of new antifungal antibiotics. I. Taxonomy, fermentation, isolation and physico-chemical and biological properties.

A complex of new antifungal antibiotics designated karnamicin was isolated from the cultured broth of Saccharothrix aerocolonigenes No. N806-4. Fifteen components have so far been isolated from the complex; the major component karnamicin B2 was identified by X-ray crystallography to be a novel molecule unrelated to known antibiotics. All components of karnamicin exhibited a rather broad spectrum of activity against fungi and yeasts with MICs ranging from 3.1 to 50 micrograms/ml.

Biosynthesis of thiamin. The precursor of the five-carbon unit of the thiazole moiety.

The precursor of the thiazole moiety of thiamin in Candida utilis was identified. Radioactive C-2, 3, 4, 5 and 6 of glucose was incorporated into C-4', 4, 5, 5' and 5" of the thiazole. This experiment shows that the precursor of the five carbon unit of thiazole is a 5-carbon compound such as ribose or ribulose derived from glucose.

Roles of cysteine as both precursor of thiazolidine 4-carboxylic acids found in human urine and possible inhibitor of endogenous N-nitrosation.

In order to compare the utility and significance of 2-R-N-nitrosothiazolidine 4-carboxylic acids excreted in human urine as an index for exposure to N-nitroso compounds, the differences in formation of N-nitrosothiazolidine 4-carboxylic acid (NTCA; R = H) and N-nitroso-2-methylthiazolidine 4-carboxylic acid (NMTCA; R = CH3) were studied in vitro. It was determined that NMTCA has a 3:1 trans:cis stereoisomer ratio, while NTCA has a 1:1 trans:cis ratio; nitrosation acts on a pH-dependent equilibrium mixture of cysteine and aldehyde in equilibrium with thiazolidine 4-carboxylic acid, with cysteine blocking N-nitrosation. Previous reports on 2-R-N-nitrosothiazolidine 4-carboxylic acids in human urine show widespread involvement of cysteine, which has a dual role with nitrosating species. In view of this and the rapid blocking of N-nitrosation and slow trans-nitrosation by cysteine at acid pH, it is suggested that there may be a hitherto unrecognized protective role of thiol functions in dietary constituents.

Metabolism of penicillins to penicilloic acids and 6-aminopenicillanic acid in man and its significance in assessing penicillin absorption.

Penicillins can be metabolized to penicilloic acids in man, the extent being dependent on the penicillin structure. In the phenoxy penicillin series, phenoxymethyl penicillin was found to be particularly unstable, but the higher homologues were more stable. In the isoxazolyl series, oxacillin was unstable, and progressive insertion of halogen in the phenyl ring increased stability. Ampicillin and amoxycillin showed some instability, ampicillin possibly being the more stable. After intramuscular administration, carbenicillin was very stable in the body, ampicillin was fairly stable, and benzyl penicillin was unstable. It is important to take into account the penicilloic acid content of urine when estimating total absorption of a penicillin. Increased stability in the body as well as slower renal clearance can lead to high concentrations in the serum. Penicilloic acids seemed to be more slowly cleared from the body than penicillins. The liver is probably the site of inactivation.

Formation of thiazolidine-4-carboxylic acid represents a main metabolic pathway of 5-hydroxytryptamine in rat brain.

Incubation of 5-hydroxytryptamine (5-HT) with rat brain homogenate resulted in the formation of (4R)-2-[3'-(5'-hydroxyindolyl)-methyl]-1,3-thiazolidine-4-carboxyl ic acid (5'-HITCA) as the major metabolite. The substance represents the condensation product of 5-hydroxyindole-3-acetaldehyde with L-cysteine. The chemical structure was confirmed by chromatographic and chemical methods as well as by fast atom bombardment mass spectrometry. Incubation of 5-HT in the presence of L-cysteine yielded the thiazolidine as the main metabolite up to 4 h. Under these conditions, the concentration of 5-hydroxyindole-3-acetic acid (5-HIAA) amounted to about 20% and 57% of 5'-HITCA (0.5 h and 4 h, respectively). In contrast to these findings, indole-3-acetic acid (IAA) was identified as the major metabolite when tryptamine was incubated under similar conditions. (4R)-2-(3'-Indolylmethyl)-1,3-thiazolidine-4-carboxylic acid (ITCA) was found to be the main conversion product of tryptamine only during the first 30 min. To investigate the fate of the thiazolidines, radiolabelled and unlabelled ITCA was incubated with rat brain homogenate. The compound was degraded enzymatically and rapidly. Subcellular fractionation revealed that the enzyme activity was present mainly in the cytosolic fraction whereas the preparation of mitochondria showed less activity. The responsible enzyme is presumably a carbon-sulfur lyase (EC 4.4.1.-). The major metabolite was isolated by HPLC and identified by mass spectrometry as well as by comparison with reference compounds to be IAA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of glycine on thiazole biosynthesis in Escherichia coli.

Glycine was found to replace thiamine thiazole for the growth of the thiazoleless mutant of Escherichia coli; it also stimulated the production of thiamine thiazole by washed cell suspensions of the mutant.

Observations on the biosynthesis of thiamine in yeast.

1. Methods are described for the isolation of radioactively pure thiamine from yeast and its degradation on a small scale to its cyclic components. 2. A degradation of the pyrimidine ring and a thin-layer method for the separation of thiamine, its derivatives and pyrimidine and thiazole residues are described. 3. [(14)C]Formate is more effectively incorporated into the pyrimidine residue than into the thiazole residue, whereas the reverse is true with l-[Me-(14)C]methionine. 4. Experiments with [Me-(14)C,(35)S]methionine demonstrate that methionine provides an intact unit for the biosynthesis of the thiazole ring. 5. [6-(14)C]Orotic acid is insignificantly incorporated into the pyrimidine residue of thiamine. 6. Experiments with [1-(14)C]- and [2-(14)C]-acetate indicate that it is incorporated as a unit into the thiazole residue, but that only C-2 is incorporated into the pyrimidine residue. 7. l-[U-(14)C]Alanine is also effectively incorporated into the thiazole residue. 8. These results are discussed in relation to possible pathways of biosynthesis of the two ring components of the thiamine molecule.

Macrophage-mediated N-nitrosation of thioproline and proline.

Thioproline (Thiazolidine-4-carboxylic acid) and proline were nitrosated by stimulated mouse macrophages in vitro. A macrophage cell line (J774.1, 1.0 x 10(6)/well, 1 ml) was incubated with Escherichia coli lipopolysaccharide, interferon-gamma and thioproline (5 mM) or proline (5 mM). After 72 hr incubation at 37 degrees C, 4 microM N-nitrosothioproline was produced. The amount of N-nitrosoproline was much lower than that of N-nitrosothioproline. Thioproline and proline inhibited the formation of carcinogenic N-nitrosomorpholine. N-nitrosothioproline and N-nitrosoproline are found as major N-nitroso compounds in human urine. Macrophage mediated N-nitrosation may contribute to the formation of these N-nitrosamino acids in the human body.

Inhibition by phenylalanine of thiazole biosynthesis in Escherichia coli.

Phenylalanine inhibited thiazole biosynthesis in a thiamine-regulatory mutant of Escherichia coli, and the inhibition was overcome by tyrosine.