Starch phosphorylase (EC 2.4.1.1) from young filaments of Cuscuta reflexa was immobilized on egg shell. The immobilized enzyme showed an alkaline shift in the optimum pH and an increase in optimum temperature compared with the soluble enzyme. The immobilized enzyme also displayed increased thermostability at 30 degrees C, with a half-life of 18 h; at this temperature, the half-life of the soluble enzyme was 6 h. The immobilized enzyme could be reused 44 times at 30 degrees C, with a decline of 10% in the enzyme activity. The increase in thermostability and reusability of the immobilized enzyme was useful for the production of glucose-1-phosphate, a cytostatic agent used in cardiopathy therapy. Two types of reactors, packed bed and fluidized bed, mere developed and operated using egg shell-bound starch phosphorylase. The fluidized bed reactor operated at 30 degrees C and a flow rate of 5.5 ml/h showed better potential for the production of glucose-1-phosphate. The product was obtained with 97% purity after adsorption chromatography on norite and ion exchange chromatography on DEAE cellulose.