THERMODYNAMICS OF IMMOBILIZED RIBONUCLEASE-A

Proteins can be bound to surfaces through chemical coupling reactions between the reactive groups of the protein and matrix. In this report, ribonuclease A immobilized on Silica beads, has been used as a model to study the modification of the properties of the enzyme after immobilization. The biological activity has been monitored by studying the binding of the inhibitor cytidine-3'-monophosphate to the free, chemically modified and immobilized RNase. The equilibrium constants and the thermodynamic parameters associated with the reaction were evaluated by calorimetric and spectrophotometric titration techniques. The thermal unfolding of free, chemically modified and immobilized RNase have been carried out by differential scanning calorimetry in various conditions. After immobilization, the process of unfolding of the protein is not comparable with that of the free enzyme. In general, a stabilizing effect was observed.