Effect of Adsorbing Materials on Radiation Inactivation of Deoxyribonuclease I

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Abstract
The presence of chemically unrelated materials with adsorptive capacity affords protection from inactivation by ionizing radiation of deoxyribonuclease I in aqueous solution. The degree of radiation inactivation is a function of the distribution of the enzymatic activity between adsorbed and soluble states. Complete protection of DNase I from inactivation by 1090 r of X-rays was achieved if essentially all the enzyme was adsorbed on powdered cellulose, whereas 63% was inactivated when the enzyme was present in aqueous solution without cellulose. The mechanism responsible for enzyme protection in the adsorbed state may involve the concentration gradient at the interface, although changes in the physicochemical state of adsorbed enzyme cannot be excluded. The biological implications of these observations are discussed.