Studies concerning the chemical equilibrium of protein-dye binding regarding the phenomenon of protein error.

SUZUKI Yuji

doi:10.2116/bunsekikagaku.42.8_497

The chemical equilibrium regarding the phenomenon of protein error of the pH indicator, which has been extensively applied to the determination of protein in biological materials, has been studied. A calculation was performed based on the assumption that the phenomenon of protein error of the pH indicator occurs due to an interaction between a positively charged amino group (-NH₃⁺) in the protein molecule and the dye anion. Although it has been reported that many equilibria exist in the interaction between a protein and a dye, since one molecule of protein reacts with several molecules of dye, it is assumed that the equilibrium constant in the first reaction is very large compared with the other equilibrium constants, and that the contribution of the reactions other than the first reaction to the protein error can be negligible. The results calculated under these assumptions accorded almost qualitatively with those obtained from various experiments, suggesting that the interaction of a positively charged amino group in a protein molecule with a dye anion play an important role in the protein error. In addition, it appeared that the phenomenon of a protein error of the pH indicator is almost not observed when the electrolytic dissociation constant (K _A )of the dye is less than about 10^-7 and the association constant (K _PA) of dye-protein complex is about 10⁶10⁷. Therefore, the use of a dye with a large electrolytic dissociation constant should provide a suitable method for the determination of protein.

Studies concerning the chemical equilibrium of protein-dye binding regarding the phenomenon of protein error.

Bibliographic Information

Search this article

Abstract

Journal

Citations (5)*help

References(14)*help

Keywords

Details 詳細情報について

Export

Report a problem