title: Digestive proteinases of Brycon orbignyanus (Characidae, Teleostei): characteristics and effects of protein quality.
abstract: Juvenile piracanjuba, Brycon orbignyanus, in the wild consume protein from both plant and animal sources. Digestion of protein in piracanjuba begins in the stomach with pepsin, at low pH, and is followed by hydrolysis at alkaline pH in the lumen of the intestine. The digestive system in piracanjuba was evaluated to characterize the enzymes responsible for the digestion of feed protein and their composition. The gastric tissue synthesizes pepsin and the intestine tissues trypsin and chymotrypsin. Operational variables were evaluated and defined for future studies of the digestive system physiology. The enzymatic activity in the intestine and the relative concentration of enzymes were heavily influenced by the composition of the feed and the feeding regime, as detected by substrate-SDS-PAGE. Piracanjuba possess a mechanism of enzyme adaptation responding to food quality and regime, by varying the amount and composition of digestive proteases. This is a requisite study to determine the enzymes digesting protein in food and their characteristics and to gain some clues about the possible regulation mechanisms of enzyme synthesis in piracanjuba.
authors.affiliation: Centro de investigaciones Biologicas, sel Noroeste, S.C. (CIB), Apartado Postal 128, B.C.S. 23000 La Paz, Mexico. fgarcia@cibnor.mx
authors.forename: Fernando L
authors.initials: FL
authors.lastname: García-Carreño
authors.forename: Cristiane
authors.initials: C
authors.lastname: Albuquerque-Cavalcanti
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Navarrete del Toro
authors.forename: Evoy
authors.initials: E
authors.lastname: Zaniboni-Filho
mesh_terms: D000222:Adaptation, Physiological; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002918:Chymotrypsin / Q000378:metabolism; D004032:Diet; D004063:Digestion; D004064:Digestive System / Q000201:enzymology*; D010450:Endopeptidases / Q000032:analysis / Q000378:metabolism*; D004795:Enzyme Stability; D005399:Fishes / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000201:enzymology; D008297:Male; D009929:Organ Size; D010434:Pepsin A / Q000378:metabolism; D013270:Stomach / Q000201:enzymology; D013379:Substrate Specificity; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D010450:Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin; D010434:Pepsin A