Estimation of the Binding Constant of 3-Ketocellobiose to a Cation from the Apparent Distribution Coefficient onto Cation-exchange Resin in the Ionic Form

Abstract

The apparent distribution coefficients, K_app, of glucose, cellobiose and 3-ketocellobiose onto the cation-exchange resins with various divinylbenzene (DYB) contents in Li⁺, Na⁺, K⁺, Ca²⁺, Sr²⁺ and Ba²⁺ forms were measured at room temperature. The K_app values of 3-ketocellobiose were greater than those of cellobiose in spite of the similar molecular masses, and were near those of glucose for the resins with any DYB content in all the ion forms tested. The K_app values of cellobiose, which were estimated from the K_app values of glucose under the assumption of no complex formation with the ions according to our previous model, coincided with the experimental values. This indicated that cellobiose formed no complex with the counter-ions within resins or that the binding constants of cellobiose to the ions were extremely low. On the other hand, it was shown that 3-ketocellobiose formed complexes with all the ions tested. The binding constants of 3-ketocellobiose to the ions were estimated based on the model, and could be correlated with the dynamic hydration numbers of the counter-ions.