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K Taraz

Publications and source records attributed to K Taraz.

At least 19 recordsLinked to original sources
PubMed2001

The structure of a pyoverdine produced by a Pseudomonas tolaasii-like isolate.

Cultures of Agaricus bisporus, the most extensively cultivated mushroom, can be infected severely by Pseudomonas tolaasii. This pathogen is characterized by the so-called white line reaction, a precipitate formed on agar plates between its colonies and those of P. reactans, both belonging to the collective species P. fluorescens. A recent study has shown that a group of P. tolaasii isolates can be subdivided into two groups or 'siderovars', based on the pyoverdines they produce (Munsch et al. 2000). One group of strains is characterized by the pyoverdine described by Demange et al. (1990). A representative of the second group (strain Ps3a) was found to produce the same pyoverdine as a strain which had been classified before as P. aureofaciens. However, based mainly on 16S rRNA gene sequence comparisons and REP-PCR generated fingerprints, the two strains are not identical. They are also distinguishable from the P. tolaasii type strain.

Agaricales↗
PubMed2000

The structure of a pyoverdine from Pseudomonas sp. CFML 96.188 and its relation to other pyoverdines with a cyclic C-terminus.

From Pseudomonas sp. CFML 96.188 a pyoverdine was isolated and its primary structure was elucidated by spectroscopic methods and degradation reactions. This strain is of interest as it accepts the structurally different pyoverdines from several other Pseudomonas strains. They all have in common as a specific structural feature a C-terminal cyclic substructure, the importance of which for the recognition of a pyoverdine at the cell surface of a given strain will be discussed.

Amino Acid Sequence↗
PubMed1999

Revised structures of the pyoverdins from Pseudomonas putida CFBP 2461 and from Pseudomonas fluorescens CFBP 2392.

Several suggestions for structures of the siderophores (pyoverdins) from Pseudomonas spp. can be found in the literature which are based on a FAB mass spectrometric analysis only. Availability of two original strains of two Pseudomonas spp. allowed to re-investigate the structure of their pyoverdins. In both cases the amino acid sequence had to be corrected. In addition, D- and L-amino acids could be identified and located in the peptide chain. The knowledge of the correct structures is important in view of an ongoing study to establish relationships between the nature of the peptide chains of pyoverdins and their recognition by outer membrane proteins.

Amino Acid Sequence↗
PubMed1999

The structure of two fengycins from Bacillus subtilis S499.

The structures of the two fengycins, lipopeptides from Bacillus subtilis, were elucidated by spectroscopic methods and chemical degradation. They show a close structural relationship to the plipastatins from Bacillus cereus differing only in the stereochemistry of the Tyr residues.

Amino Acid Sequence↗
PubMed1996

Studies on the essential oil from guarana.

The essential oil from guarana [Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke] was analysed. Nine components were identified, namely (2) methylbenzenes, (1) cyclic monoterpene and (2) cyclic sesquiterpene hydrocarbons, (2) methoxyphenylpropenes and (2) alkylphenol derivatives. The alleged psychoactivity of the essential oil is presumably due to the identified constituents estragole and anethole. Any contribution of aminated metabolites of estragole/anethole to the alleged psychoactivity of the essential oil of guarana can be excluded. Neither the psychoactive 4-methoxyamphetamine nor tert-aminoketones could be traced in human urine after oral application of guarana.

Beverages↗
PubMed1993

Pseudomonas fluorescens var. aluphilia--the influence of Al3+ on the growth rate and formation of phenazines.

The thin-layer chromatographic characterization of phenazine derivatives formed by a subspecies of Pseudomonas fluorescens under iron deficiency conditions in the presence of Al3+ showed that regarding type and quantity they were relatively different from phenazines generated on the basis of Be(2+)-containing culture media or containing neither Be2+ ions nor Al3+ ions. A comparison has shown that bacterial synthesis of phenazine derivatives is stimulated more by Be2+ ions than by Al3+ ions.

Aluminum↗
PubMed1990

Isolation of Pseudomonas fluorescens producing phenazine derivatives exclusively under strains conditions of iron deficiency.

We succeeded in isolating biotypes of Pseudomonas fluorescens forming phenazine derivatives exclusively under conditions iron deficiency. A culture medium containing traces of beryllium with glucose as the only carbon source allowed these microorganisms to grow under production of a brilliant red colour. Without beryllium the colonies were brown in colour. Spectroscopic investigations showed the red pigment to be a mixture of di- and trihydroxyphenazine carboxylic acid. UV/VIS measurements of the culture medium indicated the additional presence of ironcomplexing proferro-rosamines.

Beryllium↗
PubMedDate not supplied

Structure and characterization of isopyoverdin from Pseudomonas putida BTP1 and its relation to the biogenetic pathway leading to pyoverdins.

Pyoverdin type siderophores produced by six fluorescent Pseudomonas strains isolated from different rhizospheres were purified and characterized. The purified ferri-pyoverdins were tested for their ability to promote the growth of other strains grown under iron deficiency conditions. Only the one obtained from Pseudomonas putida BTP1 did not act as a growth promoter. The structure of the BTP1 siderophore was elucidated by spectroscopic methods and degradation studies. It turned out that it contains a chromophore which differs from the one typical for pyoverdins insofar as it carries the carboxyl group in 3- rather than in 1-position ((3S)-5-amino-1,2-dihydro-8,9-dihydroxy-3H-pyrimido[1,2a]quinoline-3- carboxylic acid). The amino group of the chromophore is substituted with the 5-carboxyl group of L-glutamic acid and its carboxyl group with the N-terminus of the peptide L-Asp-L-Ala-L-Asp-D-N5-Ac-N5-OH-Orn-L-Ser-L-c-N5-OH-Orn. This isopyoverdin fits into the biogenetic scheme which postulates ferribactins as the precursors of pyoverdins.

Amino Acid Sequence↗
PubMedDate not supplied

Structure elucidation of azotobactin 87, isolated from Azotobacter vinelandii ATCC 12837.

Chromopeptide siderophores (azotobactin 87-I and -II) were isolated from an iron deficient culture medium of Azotobacter vinelandii ATCC 12837 (= DSM 87). Their structures were elucidated by chemical degradation studies and spectroscopic methods, especially 2D-NMR-techniques. Total assignments of 1H-, 13C-, and 15N-resonances based on 2D-HOHAHA-, 1H/13C-HMQC-, 1H/13C-HMBC-, 1H/15N-HMQC/TOCSY-, and 1H/15N-HMBC-experiments are given as well as sequential information derived from 1H/1H-NOESY-, 1H/13C-HMBC- and 1H/15N-HMBC-experiments. Both Az 87-I and Az 87-II consist of a tetracyclic chromophore-- (1S)8,9-dihydroxy-4-oxo-2,3,4,5-tetrahydro-1H,10cH-3a,5,10b- triazaacephenantrylene-1-carboxylic acid--and a decapeptide chain linked with the N-terminus to the carboxy group of the chromophore containing also modified, non-proteinogenic amino acids. The sequence L-Ser-D-Ser-L-Hse-Gly-D-threo-OHAsp-Hse-Hse-Hse-D-N5OH-N5-R- Hbu-Orn-L-Hse was determined for Az 87-I, while Az 87-II contains a C-terminal L-Hse-lactone instead. Iron is chelated by the catecholic group of the chromophore, the beta-hydroxy aspartic acid, and the hydroxamate function formed by N5-hydroxyornithine and R-beta-hydroxybutyric acid.

Amino Acid Sequence↗
PubMedDate not supplied

Succinopyoverdins--a new variety of the pyoverdin chromophore.

Pseudomonas spp. of the fluorescent group produce siderophores (so-called pyoverdins) consisting of a peptide chain attached to a pyrimidoquinoline ring system which is derived from a condensation product of L-Dab and D-Tyr. Commonly several related compounds are found to accompany the pyoverdins having the same peptide chain, but differing in the heterocyclic part. The structure elucidation of a new variety (succinopyoverdin) is described here.

Molecular Structure↗
PubMedDate not supplied

Can the peptide chain of a pyoverdin be bound by an ester bond to the chromophore?--The old problem of pseudobactin 7SR1.

The structure which had been proposed for the pyoverdin named pseudobactin 7SR1 (Yang and Leong, 1984) differed from those of all other pyoverdins investigated so far: its peptide chain was supposedly linked to the chromophore not by an amide bond originating from its N-terminal amino acid, but rather by an ester bond involving one of the three Ser. It will be shown that the peptide chain of pseudobactin 7SR1 is actually bound to the chromophore amidically by its N-terminal Ser and that it comprises a cyclodepsipeptidic substructure with an ester bond between the C-terminal Thr and the OH-group of the second Ser in the chain.

Esters↗
PubMedDate not supplied

The siderophores of Pseudomonas fluorescens 18.1 and the importance of cyclopeptidic substructures for the recognition at the cell surface.

The structure of the pyoverdin siderophore of Pseudomonas fluorescens 18.1 was elucidated by spectroscopic methods and chemical degradation. By cross feeding studies structurally closely related pyoverdins containing a C-terminal cyclopeptidic substructure were tested regarding the mutual recognition by the producing strains. Partial recognition of foreign pyoverdins was observed.

Amino Acid Sequence↗
PubMedDate not supplied

Anachelin, the siderophore of the cyanobacterium Anabaena cylindrica CCAP 1403/2A.

A catecholate siderophore - anachelin - has been isolated from the cyanobacterium Anabaena cylindrica CCAP 1403/2A. The central part of the siderophore is a tripeptide consisting of L-Thr, D-Ser and L-Ser. Its C-terminus is linked amidically to a 1,1-dimethyl-3-amino-1,2,3,4-tetrahydro-7,8-dihydroxyquinolinium system and its N-terminus to 6-amino-3,5,7-trihydroxyheptanoic acid. The 7-hydroxyl group of the latter is esterified with salicylic acid whose carboxyl group is condensed with the 6-amino group to an oxazoline ring. Anachelin is the first genuine siderophore of a cyanobacterium whose structure has been elucidated.

Anabaena↗