To liberate the hydrogen, Virginia Tech scientists separated a number of enzymes from their native microorganisms to create a customized enzyme cocktail that does not occur in nature.

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The reason for this is believed to be to stop cancer in its tracks by preventing tumour cells from dividing more than a certain number of times. (Successful cancers often have a special enzyme that repairs telomeres.) The cost is that, eventually, even healthy tissue cannot renew itself.

ECONOMIST: Ageing

To get around the problem, a small number of plants have evolved a way to enrich the carbon-dioxide concentration around the rubisco enzyme, and to suppress the oxygen concentration.

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