title: Partial purification of pepsins from adult and juvenile salmon fish Oncorhynchus keta. Effect of NaCl on proteolytic activities.
abstract: 1. Two pepsins, designated Pepsin I and Pepsin II, were isolated and partially characterized from the stomach of the adult stage salmon Oncorhynchus keta. This stage is developed in a marine environment. 2. One pepsin, designated Pepsin II, was isolated from the stomach of the juvenile stage salmon Oncorhynchus keta. This stage is developed in an estuarine environment. 3. The enzymes were partially purified by ammonium sulfate precipitation, ion exchange chromatography and gel filtration. 4. Pepsins I and II from adults and Pepsin II from juvenile showed proteolytic activity on acid-denatured hemoglobin with a pH optimum of 3. 5. The mol. wt determined by gel filtration on Sephadex G-100 of Pepsin I from juvenile species was found to be 32,000 whereas a value of 27,000 was determined for Pepsin II from juvenile and adult fish. 6. In contrast with Pepsin II, Pepsin I was activated by NaCl. It is suggested that the appearance of NaCl-activated pepsin would represent and adaptive response of the organism to the change from a low to a high salinity environment.
mesh_terms: D000375:Aging; D000818:Animals; D005753:Gastric Mucosa / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D010434:Pepsin A / Q000302:isolation & purification / Q000378:metabolism*; D012474:Salmon / Q000254:growth & development*; D012965:Sodium Chloride / Q000494:pharmacology*; D013270:Stomach / Q000254:growth & development
chemical_list: D007527:Isoenzymes; D012965:Sodium Chloride; D010434:Pepsin A