Interactions and compatibility of ribuloso-1,5-bisphosphate carboxylase/oxygenase from alfalfa with pectin in aqueous medium

HPLC, dynamic light scattering, CD- and fluorescent spectroscopy, and phase analysis methods are used to study the effect of Coulomb and non-Coulomb i nteractions between alfalfa rubisco and pectin on their thermodynamic compa tibility. In the acid region of pH, water insoluble interpolymer complexes stabilized by both the Coulomb and non-Coulomb bonds are formed. In the neu tral and alkaline regions, the complexes soluble in water are formed via no n-Coulomb bonds, due to both the hydrophobic interaction involving the este r groups of pectin and the hydrogen bonding between dissimilar molecules. T he compatibility of these biopolymers is sensitive to the esterification de gree of pectin. With the latter increasing, compatability increases at neut ral pH, but decreases considerably in the acidic region. (C) 2000 Elsevier Science B.V. All rights reserved.