title: The effect of calcium on the tryptic digestion of bovine intestinal calcium-binding protein.
abstract: The tryptic hydrolysis of bivine intestinal calcium-binding protein in the presence and absence of excess calcium has been investigated. Calcium-binding activity and immunological reactivity of the protein were not significantly affected in the presence of 1.0 mM CaCl2 following 24 h incubation at 38 degrees C with trypsin at ratios of 1:9 of enzyme to calcium-binding protein. Some modification of the protein did occur under these conditions, however, since analysis by analytical acrylamide gel electrophoresis indicated the formation of a more rapidly-migrating species from the slower-moving original protein band. Omission of added calcium from the incubation medium resulted in rapid and essentially complete destruction of calcium-binding activity and immunological reactivity, and the formation of peptides of low molecular weight. This provides evidence that the conformation of the calcium-binding protein in the presence of calcium differs from that in its absence.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D002417:Cattle; D007422:Intestines; D014357:Trypsin / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D014357:Trypsin; D002118:Calcium