Isoelectric focusing of the phosphoprotein of rat-incisor dentin in ampholine and acid pH gradients. Evidence for carrier ampholyte-protein complexes
Jonsson, M.; Fredriksson, S.; Jontell, M.; Linde, A.
Journal of Chromatography 157: 235-242
1978
ISSN/ISBN: 0021-9673 PMID: 29908 Document Number: 124641
Rat-incisor phosphoprotein (RIP) was subjected to isoelectric focusing at 4.degree. C in an Ampholine pH gradient of 2.5-4 and an acid pH gradient created by electrolysis of a system of acids and acidic ampholytes and covering the pH range 0.5-3.5. In the Ampholine gradient, the RIP unexpectedly formed several adjacent and strongly opalescent bands in the pH range 2.5-3.1. These bands, which migrated slowly toward the anode on prolonged focusing, are interpreted as the result of an interaction between the amino groups of the Ampholine and the numerous phosphate groups of the protein. In the acid pH gradient, the RIP focused into 1 narrow zone corresponding to an isoelectric pH of 1.1 at 4.degree. C. This value is consistent with the amino-acid composition and the phosphate content of the protein.