RESUMEN
The fruit-eating teleost fish, the pacu Piaractus mesopotamicus (Characiformes, Characidae) is classified along with the carp and the catfish in the superorder Ostariophysi. The pacu is able to survive and grow in captive conditions feeding exclusively on carbohydrates. Hormonal polypeptides in an extract of pacu Brockmann bodies were purified to homogeneity by reversed phase HPLC and their primary structures determined by automated Edman degradation. Pacu insulin contains only two substitutions, Glu-->Asp at A15 and Thr-->Ser at B24 (corresponding to B22 in mammalian insulins) compared with carp insulin. The B-chains of both insulins contain a dipeptide extension to the N-terminus and a deletion of the C-terminal residue compared with human insulin. Pacu glucagon differs from catfish glucagon by a single substitution at position 17 (Arg-->Gln. The primary structure of the 34 amino acid residue glucagon-like peptide (GLP) differs from catfish GLP only at positions 12 (Ser-->Ala) and 33 (Pro-->Gln). In common with other teleost species, the pacu expresses two somatostatin genes. Somatostatin-14, derived from preprosomatostatin-I (PSS-I), is identical to mammalian/catfish somatostatin-14. Although pacu somatostatin-II was not identified in this study, a peptide was purified that shows 67% sequence identity with residues (1-58) of catfish preprosomatostatin-II (PSS-II). This relatively high degree of sequence similarity contrasts with the fact that catfish PSS-II shows virtually no sequence identity with the corresponding PSS-II from anglerfish (Acanthopterygii) and trout (Protoacanthopterygii). A comparison of the primary structures of the islet hormones suggest that amino acid sequences may have been better conserved within the Ostariophysi than in other groups of the taxon Euteleostei that have been studied.
Asunto(s)
Peces/metabolismo , Glucagón/química , Glucagón/aislamiento & purificación , Insulina/química , Insulina/aislamiento & purificación , Precursores de Proteínas/química , Precursores de Proteínas/aislamiento & purificación , Somatostatina/química , Somatostatina/aislamiento & purificación , Secuencia de Aminoácidos , Aminoácidos/análisis , Animales , Cromatografía Líquida de Alta Presión , Femenino , Masculino , Datos de Secuencia Molecular , Proglucagón , Homología de Secuencia de Aminoácido , Factores de TiempoRESUMEN
A process for purifying bovine pancreatic glucagon as a by-product of insulin production is described. The glucagon-containing supernatant from the alkaline crystallization of insulin was precipitated using ammonium sulfate and isoelectric precipitation. The isoelectric precipitate containing glucagon was then purified by ion-exchange chromatography on Q-Sepharose FF, gel filtration on Sephadex G-25 and ion-exchange chromatography on S-Sepharose FF. A pilot scale test was performed with a recovery of 87.6 percent and a purification factor of 8.78 for the first chromatographic step, a recovery of 75.1 percent and a purification factor of 3.90 for the second, and a recovery of 76.2 percent and a purification factor of 2.36 for the last one. The overall yield was 50 percent, a purification factor of 80.8 was obtained and the fraction containing active glucagon (suitable for pharmaceutical preparations) was 84 percent pure as analyzed by HPLC.
Asunto(s)
Bovinos , Glucagón/aislamiento & purificación , Insulina/aislamiento & purificación , Páncreas/química , Cromatografía en Gel , Cromatografía por Intercambio IónicoRESUMEN
A process for purifying bovine pancreatic glucagon as a by-product of insulin production is described. The glucagon-containing supernatant from the alkaline crystallization of insulin was precipitated using ammonium sulfate and isoelectric precipitation. The isoelectric precipitate containing glucagon was then purified by ion-exchange chromatography on Q-Sepharose FF, gel filtration on Sephadex G-25 and ion-exchange chromatography on S-Sepharose FF. A pilot scale test was performed with a recovery of 87.6% and a purification factor of 8.78 for the first chromatographic step, a recovery of 75.1% and a purification factor of 3.90 for the second, and a recovery of 76.2% and a purification factor of 2.36 for the last one. The overall yield was 50%, a purification factor of 80.8 was obtained and the fraction containing active glucagon (suitable for pharmaceutical preparations) was 84% pure as analyzed by HPLC.