The mechanism of the phosphate transfer process in the enzymic reacton catalyzed by rabbit muscle phosphoglucomutase (PGM) will be studied by (a) attempting to prepare an absorbant suitable for affinity chromatography of the enzyme to aid in its purification; (b) continuing attempts to obtain crystals of the enzyme that are adequate for x-ray diffraction studies: (c) continuing 31P-NMR studies to determine the distance between the bound metal ion and the enzymic phosphate group; (d) continuing studies on the extent of the conformational change in the enzyme that accompanies the catalytic transfer process; (e) continuing studies to determine the source of the more than 10 to the 8th power-fold difference in the reactivity of the Li ion and Mg2 ion forms of the enzyme, in the face of a number of strikingly similar structural features between the two. BIBLIOGRAPHIC REFERENCES: The Construction and Testing of a Simple, Slow Delivery-Rapid Quench Apparatus. W.J. Ray, Jr., and J.W. Long (1976), Biochemistry, in press. Thermodynamics and Mechanism of the PO3-Transfer Process in the Phosphoglucomutase Reaction. W.J. Ray, Jr., and J.W. Long (1976), Biochemistry, in press.