This deep-sea enzyme survives heat that destroys most proteins

Microorganisms are capable of some extraordinary chemistry. One example is nitrogen fixation, a process that converts nitrogen gas (N 2 ) into a form living organisms can actually use. Nitrogen makes up about 78 percent of Earth's atmosphere, but plants and animals cannot use it directly because the two nitrogen atoms in N 2 are joined by an exceptionally strong chemical triple bond.

Certain microorganisms have evolved a way around this problem. They can break that bond and transform N 2 into ammonia, which can then be incorporated into biological molecules. One of these organisms is the deep-sea archaeon Methanocaldococcus infernus , which lives in volcanic marine environments where vent fluids can reach temperatures above the boiling point of water.