Enzymatic Production of High Concentration Glucose-1-Phosphate

Abstract

Glucose-1-phosphate (G-1-P) is a biological product which, along with its derivatives, has various physiological applications. In order to develop an efficient industrial process for G-1-P, enzymatic production of high concentration G-1-P was attempted by using phosphorylase purified from potatoes as an enzyme, several kinds of linear and branched dextrin differing in chain length and a mixture of KH₂PO₄ and K₂HPO₄ (Pi) as substrates. Since the maltotetraose is not active as a substrate for production of G-1-P, effective glucan concentration was defined on a basis of moles of glucose (C_eG) excluding a segment of maltotetraose from dextrin. Furthermore, since the reaction was a complicated reversible reaction involving many kinds of glucan differing in chain length, the inhibitory effect of a high concentration of substrate for the enzyme, an apparent equilibrium constant K_app was defined. K_app was expressed as a function of initial concentration of glucan (C_eG,0) and phosphate (C_P,0). The concentration of G-1-P finally obtained at the equilibrium (C_G1P,eq) could be easily calculated from K_app regardless of chain length and branch structures of glucan. As a result, a diagram expressing C_G1P,eq as a function of C_eG,0 and C_P,0 was proposed. A high concentration of G-1-P, namely 230 mM G-1-P was experimentally obtained when C_eG,0 and C_P,0 were 516 and 3000 mM, respectively, and the enzymatic activity was 100 U·mL^–1.