Molecular model of the structure of vitamin B12, 1957-1959.

Vitamin B12 (cyanocobalamin) is produced by microorganisms in the gut. Deficiency leads to pernicious anaemia, which is the poor development of red blood cells resulting in the posible degeneration of the spinal cord. The molecular structure of vitamin B12 was identified by the British X-ray crystallographer Dorothy Crowfoot Hodgkin in 1957.