RESUMEN
Calf diarrhea due to infection by enterotoxigenic Escherichia coli was treated by administration of glycoprotein glycans derived from bovine plasma. The glycan moieties of the nonimmunoglobulin fraction of plasma mimicked the oligosaccharide moiety of intestinal receptors recognized by K99 pili. These glycoprotein glycans inhibited adhesion of E. coli K99+ ST+ to erythrocyte glycoconjugates in vitro, and they protected colostrum-deprived newborn calves against lethal doses of enterotoxigenic E. coli (10(10) bacteria). Adhesion of bacteria to the intestines (duodenum, jejunum, and ileum) was significantly reduced (by 2 orders of magnitude) in treated calves.
Asunto(s)
Infecciones por Escherichia coli/terapia , Glicopéptidos/administración & dosificación , Animales , Adhesión Bacteriana/efectos de los fármacos , Secuencia de Carbohidratos , Bovinos , Enfermedades de los Bovinos/terapia , Diarrea/terapia , Diarrea/veterinaria , Heces/microbiología , Hemaglutinación/efectos de los fármacos , Concentración de Iones de Hidrógeno , Mucosa Intestinal/microbiología , Datos de Secuencia Molecular , Potasio/metabolismo , Sodio/metabolismo , Relación Estructura-ActividadAsunto(s)
Aminoacil-ARNt Sintetasas/metabolismo , Cloroplastos/enzimología , Metionina-ARNt Ligasa/metabolismo , Citoplasma/metabolismo , Electroforesis en Gel de Poliacrilamida , Escherichia coli , Focalización Isoeléctrica , Metionina-ARNt Ligasa/aislamiento & purificación , Peso Molecular , ARN Bacteriano/metabolismo , Semillas , TriticumAsunto(s)
Aminoacil-ARNt Sintetasas/metabolismo , Complejos Multienzimáticos/metabolismo , Plantas/enzimología , Arginino-ARNt Ligasa/metabolismo , Leucina-ARNt Ligasa/metabolismo , Metionina-ARNt Ligasa/metabolismo , Peso Molecular , Fenilalanina-ARNt Ligasa/metabolismo , Fracciones Subcelulares/enzimología , Triticum/enzimologíaAsunto(s)
Aminoacil-ARNt Sintetasas/metabolismo , Arginino-ARNt Ligasa/metabolismo , Leucina-ARNt Ligasa/metabolismo , Ribosomas/metabolismo , Aminoácidos/administración & dosificación , Arginino-ARNt Ligasa/antagonistas & inhibidores , Cinética , Leucina-ARNt Ligasa/antagonistas & inhibidores , Peso Molecular , Conformación Proteica , Albúmina Sérica Bovina/metabolismo , Triticum/metabolismoRESUMEN
From wheat germ, a phenylalanyl-tRNA synthetase (E.C.6.1.1.20) has been isolated and purified 187 fold by means of ammonium sulfate fractionation (40-50 per cent) followed by Sephadex G-200 gel filtration, chromatographies on DEAE-cellulose and hydroxyapatite. The enzyme appears to be homogeneous on Sephadex G-200 molecular filtration and polyacrylamide gel electrophoresis. Molecular weight determinations by sucrose gradient centrifugation, gel filtration and gel electrophoresis give an average of 250 00 daltons. The enzyme is dissociated in 1 per cent sodium dodecyl sulfate into two different equimolar components of 80 000 and 50 000 daltons ; this result suggests that the phenylalanyl-tRNA synthetase has a subunit structure : alpha2 beta2. Dissociation with sodium dodecyl sulfate and dithiothreitol gives four other components, probably resulting from the breakdown of the subunits. Optima values of pH, Mg2+ and K+ concentrations, effect of SH-compnents, kinetic parameters have been determined in the aminoacylation reaction. Physical and catalytic properties of wheat germ phenylalanyl-tRNA synthetase appear very similar to those of the yeast and E. coli enzymes.
Asunto(s)
Aminoacil-ARNt Sintetasas/aislamiento & purificación , Fenilalanina-ARNt Ligasa/aislamiento & purificación , Triticum/enzimología , Cromatografía en Gel , Electroforesis en Gel de Poliacrilamida , Cinética , Sustancias Macromoleculares , Magnesio , Peso Molecular , Péptidos/análisis , Fenilalanina-ARNt Ligasa/metabolismo , Potasio , Conformación Proteica , Semillas/enzimología , Reactivos de Sulfhidrilo/farmacología , UltracentrifugaciónRESUMEN
Aurin tricarboxylic acid (A.T.A.), an inhibitor of protein biosynthesis (initiation and elongation steps), acts also as a competitive inhibitor of phenylalanine, in the ATP-PPi exchange and tRNAPhe aminoacylation reactions catalysed by cytoplasmic wheat germ phenylalanine:tRNA ligase.