Pressure-induced structural changes in wet vitamin B12

The effects of pressure on the structure of cyanocobalamin (vitamin B12) have been investigated by compressing a single crystal grown from water together with its mother liquor to 1.0 GPa. The structure of a crystal grown from water in situ in a capillary has also been re-determined at room temperature and pressure. A conformational rearrangement of selected amide side chains, reduced displacement parameters and remarkable solvent ordering have been observed at high pressure.