1. Polysialic acids are linear homopolymers of N-acetylneuraminic acid (Neu5Ac), N-glycolylneuram... more 1. Polysialic acids are linear homopolymers of N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc) and deaminated neuraminic acid (KDN) residues joined by alpha 2,8, alpha 2-9 or alpha 2,8/alpha 2,9 ketosidic linkages. 2. They occur in glycoproteins of embryonic neural membranes (playing a role of neural cell adhesion molecules), in non-neural tissues (postnatal kidney), tumours, (neuroectodermal tumours), fish eggs and in the capsule of certain bacteria such as Neisseria meningitidis group B. 3. These polymers are synthesized through reactions which involve (a) the synthesis of sialic acid; (b) its activation to a cytidine monophosphate sugar nucleotide and (c) the polymerization of the different residues by a polysialyl-transferase complex. 4. Polysialic acids are involved in organogenesis and in cell growth. In several tissues they act as oncodevelopmental antigens, and in bacteria are also virulent determinants.
A suitable and rapid method for the simultaneous determination of different aliphatic penicillins... more A suitable and rapid method for the simultaneous determination of different aliphatic penicillins is described. Butyryl-, pentanoyl-, hexanoyl-, heptanoyl-, octanoyl-, nonanoyl- and decanoylpenicillin can be completely separated by high-performance liquid chromatography using an isocratic elution mode (50 mM H2KPO4, pH 5.0:methanol, 45:55 v/v). Under these conditions, retention times for C4 to C10 aliphatic side-chain penicillins were 2.5, 2.8, 4.1, 5.8, 8.9, 15.3, and 28.2 min. The benzylpenicillin retention time was 3.3 min.
SummaryThe substrate specificity of the two polymerases (PhaC1 and PhaC2) involved in the biosynt... more SummaryThe substrate specificity of the two polymerases (PhaC1 and PhaC2) involved in the biosynthesis of medium‐chain‐length poly‐hydroxyalkanoates (mcl PHAs) in Pseudomonas putida U has been studied in vivo. For these kind of experiments, two recombinant strains derived from a genetically engineered mutant in which the whole pha locus had been deleted (P. putida U Δpha) were employed. These bacteria, which expresses only phaC1 (P. putida U Δpha pMC‐phaC1) or only phaC2 (P. putida U Δpha pMC‐phaC2), accumulated different PHAs in function of the precursor supplemented to the culture broth. Thus, the P. putida U Δpha pMC‐phaC1 strain was able to synthesize several aliphatic and aromatic PHAs when hexanoic, heptanoic, octanoic decanoic, 5‐phenylvaleric, 6‐phenylhexanoic, 7‐phenylheptanoic, 8‐phenyloctanoic or 9‐phenylnonanoic acid were used as precursors; the highest accumulation of polymers was observed when the precursor used were decanoic acid (aliphatic PHAs) or 6‐phenylhexanoic a...
El término catabolón ha sido acuñado para definir una unidad funcional compleja integrada por var... more El término catabolón ha sido acuñado para definir una unidad funcional compleja integrada por varias rutas catabólicas independientes (rutas periféricas) que confluyen en una ruta central o ruta de convergencia (núcleo del catabolón) y que sirve para la degradación de diferentes compuestos relacionados estructuralmente. La ruta central es la encargada de transformar el intermediario común (compuesto que da nombre al catabolón) en metabolitos generales. Todas las rutas que componen los catabolones suelen regularse coordinadamente, de tal forma que la afluencia de catabolitos a la ruta central está sometida a un estricto control jerárquico. Los catabolones pueden considerarse como el primer estadio de integración metabólica por lo que su comprensión es básica para entender cómo han evolucionado las rutas catabólicas en microorganismos. El primer modelo descrito, de ahí su calificación de paradigma, fue el catabolón del fenilacetil-CoA, que incluye todas aquellas rutas mediante las cua...
The aroA gene of Yersinia ruckeri, which encodes 5-enolpyruvylshikimate 3-phosphate synthase, was... more The aroA gene of Yersinia ruckeri, which encodes 5-enolpyruvylshikimate 3-phosphate synthase, was insertionally inactivated with a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of Y. ruckeri 21102 O1 by means of the suicide vector pIVET8. The Y. ruckeri aroA::Kan(r) mutant was highly attenuated when inoculated intraperitoneally into rainbow trout, with a 50% lethal dose of >5 x 10(7) CFU. The mutants were not recoverable from the internal organs 48 h post-inoculation or later. The vaccination of rainbow trout with the AroA mutant as a live vaccine conferred significant protection (relative percentage survival = 90%) against the pathogenic wild-type strain of Y. ruckeri.
1. Polysialic acids are linear homopolymers of N-acetylneuraminic acid (Neu5Ac), N-glycolylneuram... more 1. Polysialic acids are linear homopolymers of N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc) and deaminated neuraminic acid (KDN) residues joined by alpha 2,8, alpha 2-9 or alpha 2,8/alpha 2,9 ketosidic linkages. 2. They occur in glycoproteins of embryonic neural membranes (playing a role of neural cell adhesion molecules), in non-neural tissues (postnatal kidney), tumours, (neuroectodermal tumours), fish eggs and in the capsule of certain bacteria such as Neisseria meningitidis group B. 3. These polymers are synthesized through reactions which involve (a) the synthesis of sialic acid; (b) its activation to a cytidine monophosphate sugar nucleotide and (c) the polymerization of the different residues by a polysialyl-transferase complex. 4. Polysialic acids are involved in organogenesis and in cell growth. In several tissues they act as oncodevelopmental antigens, and in bacteria are also virulent determinants.
A suitable and rapid method for the simultaneous determination of different aliphatic penicillins... more A suitable and rapid method for the simultaneous determination of different aliphatic penicillins is described. Butyryl-, pentanoyl-, hexanoyl-, heptanoyl-, octanoyl-, nonanoyl- and decanoylpenicillin can be completely separated by high-performance liquid chromatography using an isocratic elution mode (50 mM H2KPO4, pH 5.0:methanol, 45:55 v/v). Under these conditions, retention times for C4 to C10 aliphatic side-chain penicillins were 2.5, 2.8, 4.1, 5.8, 8.9, 15.3, and 28.2 min. The benzylpenicillin retention time was 3.3 min.
SummaryThe substrate specificity of the two polymerases (PhaC1 and PhaC2) involved in the biosynt... more SummaryThe substrate specificity of the two polymerases (PhaC1 and PhaC2) involved in the biosynthesis of medium‐chain‐length poly‐hydroxyalkanoates (mcl PHAs) in Pseudomonas putida U has been studied in vivo. For these kind of experiments, two recombinant strains derived from a genetically engineered mutant in which the whole pha locus had been deleted (P. putida U Δpha) were employed. These bacteria, which expresses only phaC1 (P. putida U Δpha pMC‐phaC1) or only phaC2 (P. putida U Δpha pMC‐phaC2), accumulated different PHAs in function of the precursor supplemented to the culture broth. Thus, the P. putida U Δpha pMC‐phaC1 strain was able to synthesize several aliphatic and aromatic PHAs when hexanoic, heptanoic, octanoic decanoic, 5‐phenylvaleric, 6‐phenylhexanoic, 7‐phenylheptanoic, 8‐phenyloctanoic or 9‐phenylnonanoic acid were used as precursors; the highest accumulation of polymers was observed when the precursor used were decanoic acid (aliphatic PHAs) or 6‐phenylhexanoic a...
El término catabolón ha sido acuñado para definir una unidad funcional compleja integrada por var... more El término catabolón ha sido acuñado para definir una unidad funcional compleja integrada por varias rutas catabólicas independientes (rutas periféricas) que confluyen en una ruta central o ruta de convergencia (núcleo del catabolón) y que sirve para la degradación de diferentes compuestos relacionados estructuralmente. La ruta central es la encargada de transformar el intermediario común (compuesto que da nombre al catabolón) en metabolitos generales. Todas las rutas que componen los catabolones suelen regularse coordinadamente, de tal forma que la afluencia de catabolitos a la ruta central está sometida a un estricto control jerárquico. Los catabolones pueden considerarse como el primer estadio de integración metabólica por lo que su comprensión es básica para entender cómo han evolucionado las rutas catabólicas en microorganismos. El primer modelo descrito, de ahí su calificación de paradigma, fue el catabolón del fenilacetil-CoA, que incluye todas aquellas rutas mediante las cua...
The aroA gene of Yersinia ruckeri, which encodes 5-enolpyruvylshikimate 3-phosphate synthase, was... more The aroA gene of Yersinia ruckeri, which encodes 5-enolpyruvylshikimate 3-phosphate synthase, was insertionally inactivated with a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of Y. ruckeri 21102 O1 by means of the suicide vector pIVET8. The Y. ruckeri aroA::Kan(r) mutant was highly attenuated when inoculated intraperitoneally into rainbow trout, with a 50% lethal dose of >5 x 10(7) CFU. The mutants were not recoverable from the internal organs 48 h post-inoculation or later. The vaccination of rainbow trout with the AroA mutant as a live vaccine conferred significant protection (relative percentage survival = 90%) against the pathogenic wild-type strain of Y. ruckeri.
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Papers by J. Luengo