3 ms·

How does all life use tungsten? I’ve never heard of that.

• adrian_b 6y ago
  I have said "molybdenum or tungsten". Most living beings use molybdenum, but tungsten can replace molybdenum and it is used for this purpose by some living beings (mostly by Archaea). It is pretty certain that the common ancestor of all existing living beings already had molybdenum enzymes, while tungsten began to be used later, as an adaptation to higher temperatures. Nevertheless, there was a hypothesis that maybe before the oxygenation of the oceans tungsten was used in preference to molybdenum, because oxygenated molybdenum compounds are more soluble than oxygenated tungsten compounds while in reduced environments their solubility properties are reversed. However this hypothesis is most likely wrong, because it is contradicted by the distribution and phylogeny of the molybdenum enzymes and tungsten enzymes, which are consistent with the universal use of molybdenum already much earlier than the evolution of the ability for water photolysis and with the gain of the ability to use tungsten as an alternative only in certain archaea and bacteria. The earliest life forms were probably dependent on having ammonia and carbon monoxide in their environment, as sources of carbon and nitrogen, in which case molybdenum is not strictly needed. The use of molybdenum enzymes enabled the use of the more abundant carbon dioxide and dinitrogen as sources of carbon and nitrogen. This achievement must have happened some time before LUCA (last universal common ancestor), which already had these enzymes.