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Cobalamin (vitamin B12)

Cobalamin is a complex molecule at the core of which is a corrin ring: a tetrapyrrole structurally homologous to heme but with a cobalt atom, rather than iron, at its center. This illustration shows the chemical structures of various vitamers. (Figure by Alsosaid 1987, 2019. Courtesy of Wikimedia Commons. Creative Commons Attribution-Share Alike 4.0 International License.)

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