Structure of the sugar phosphates by x-ray method

The structure of a-Glucose-1-Phosphate, the Cori Ester, in the form of its dipotassium salt dihydrate has "been determined and the structure compared with those of analogous compounds. The methods used were hased mainly on the three-dimensional vector function, partly using the isomorphous diammonium-Glucose1-Pho8phate dihydrate. The information derived from the short intramolecular vectors appearing round the origin of the 'sharpened' vector map was found to he particularly valuable. Direct methods of sign determination were also examined and found to he potentially useful.Refinement was carried out initially by Fourier methods and finally by the method of Least Squares, all such calculations being done on the D.E.U.C.E. Computer of Glasgow University. The molecular structure is confirmed as being that found by purely chemical methods. The Glucose-1-Phosphate molecule possesses the long (1.59 °A) phosphorous-ester oxygen "bond which is found in other sugar phosphate structures and which seems to he characteristic of this class of compound. In addition, the bond from carbon (1) to the ester oxygen is shorter (1.37 °A) than average. The angle at this oxygen, 124°, is rather wide.The crystal structure itself is held together by a comprehensive system of non-covalent bonds linking the cations, the free oxygens of the phosphate group, the hydroxyl groups of the sugar ring, and the water molecules. The completeness of this system explains the comparative hardness of the crystal and its lack of any preferred cleavage