The effect of calcium on the tryptic digestion of bovine intestinal calcium-binding protein

• Published in: Biochimica et biophysica acta Vol. 412; no. 2; p. 256
• Main Authors: Fullmer, C S, Wasserman, R H, Hamilton, J W, Huang, W Y, Cohn, D V
• Format: Journal Article
• Language: English
• Published: Netherlands 15-12-1975
• Subjects: Animals; Calcium - metabolism; Calcium - pharmacology; Carrier Proteins - immunology; Carrier Proteins - metabolism; Cattle; Intestines; Trypsin - metabolism
• ISSN: 0006-3002
• DOI: 10.1016/0005-2795(75)90039-2

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.