The nickel containing enzyme F 430 is a coenzyme for vitamine B12. In some organisms, it takes over the role of the cobalamines. This means that it takes part in a large number of biosynthetic reactions.
This relatively large protein has two nickel centers. The nickel atoms are bound to a distorted porphyrin system and are axially coordinated by an asparagine residue and a mercapto moiety.