The role of molybdenum in human biology

Molybdenum, because of its unique chemistry, is the biological catalyst for reactions in which proton and electron transfer, and possibly oxygen transfer, are coupled. The molybdoenzymes in man are sulphite oxidase, xanthine oxidase/dehydrogenase and aldehyde oxidase. The former is essential for detoxication of the sulphite arising from metabolism of sulphur-containing amino acids, from ingestion of bisulphite preservative and from inhalation of sulphur dioxide, an atmospheric pollutant. Whether, or not, any of the reactions catalysed by xanthine oxidase/dehydrogenase and aldehyde oxidase are necessary for human well-being has yet to be established.