A normal constituent of resting muscle, probably always existing in equilibrium with fructose-6-phosphate. For the enzymatic conversion from the 1-phosphate see α-Glucose-1-phosphate. Isoln from a crude mixture of hexose phosphates, obtained by yeast fermentation: Robison, King, Biochem. J. 25, 323 (1931). Prepn by the action of phosphoglucomutase on α-glucose-1-phosphate: Colowick, Sutherland, J. Biol. Chem. 144, 423 (1942); from acetone glucose: Levene, Raymond, ibid. 92, 757 (1931); by phosphorylation of 1,2,3,4-tetraacetylglucose followed by deacetylation: Fischer, Lardy, ibid. 164, 513 (1946); Biochem. Prep. 2, 39 (1952). Prepn from starch: de Chatelperron et al., FR 1379068 (1964), C.A. 62, 9394b (1965).