Three new nickel enzymes from anaerobic bacteria

Until recently nickel was not considered to be an element of biological importance. Nutritional studies have shown, however, that many eucaryotic and procaryotic organism are dependent on the transition metal for growth. Four enzymes are presently known to contain nickel: urease from plant and from bacteria; methyl CoM reductase from methanogenic bacteria; all "uptake" hydrogenases investigated so far; and carbon monoxide dehydrogenase from anaerobic bacteria. The prosthetic group of the methyl CoM reductase has been identified as a nickel tetrapyrrole, the structure of which has been elucidated.