RESUMEN
The effect of protein depletion followed by refeeding with a normal diet on the content of mouse liver cytosolic proteins was studied. By peptide-mass fingerprinting and N-terminal sequencing, three polypeptides whose contents changed with dietary protein level were identified as glutathione S-transferases (GST) Yb1, Yc and Yf subunits. Five days of depletion caused the increase of Yb1 and Yf (21.6% and 78.5%, respectively) and the decrease of Yc (31.2%). After two days of refeeding, Yb1 and Yc were practically restored, while the neoplastic marker Yf remained higher (63.4%). None of the nutritional conditions tested induced new GSTs. While protein depletion-refeeding altered the ratios between the constitutive GST subunits, total liver GST content and activity were unaffected by depletion and slightly increased by refeeding. The increased amounts of Yb1 and Yf, and the maintenance of total GST content, indicate that during protein depletion, the GST subunits levels are controlled by mechanisms different from the majority of cytosolic proteins.
Asunto(s)
Proteínas en la Dieta/administración & dosificación , Glutatión Transferasa/metabolismo , Hígado/enzimología , Deficiencia de Proteína/metabolismo , Secuencia de Aminoácidos , Animales , Femenino , Glutatión Transferasa/química , Glutatión Transferasa/aislamiento & purificación , Espectrometría de Masas , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , TripsinaRESUMEN
Reduced and carbamidomethylated alpaca growth hormone was submitted to tryptic digestion. Peptides in the mixture were purified by reverse phase HPLC and N-terminal determination and an amino acid analysis of each was performed. Data obtained and the already known primary structure of the equine growth hormone allowed the assembly-by homology-of a definite sequence of amino acids for the polypeptide chain of the protein. Present data provide further information about the relationship between growth factors.