DYE-BINDING STOICHIOMETRY AND SELECTIVITY OF CRESOL RED WITH VARIOUS PROTEINS

Dye-binding stoichiometry and selectivity of the reactions of several standard proteins and protein matrices with the phthalein dye cresol red (CR) are presented. Spectrophotometric measurements show that the interactions are selective; amino acids, peptides, and albumin-type proteins do not react at all. The optimum analytical conditions of the reactive proteins-human gamma globulin (HGG), casein (C), milk protein (MP), soya bean (SBM), meat (MM), and fish meals (FM)-with CR are given. Dye-binding values obtained with soya bean meals are complemented by the sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns (SDS-PAGE) of the same samples, in order to show a qualitative picture of the molecular weight distribution of three untreated samples when comparing them to their respective denatured ones. © 1989.