Carbon-fixing enzyme 10 times more abundant than previously thought

This is how Manajit Hayer-Hartl from the Max Planck Institute of Biochemistry, Germany, sums up her thoughts on a new analysis that the global abundance of plants' carbon dioxide converting enzyme is an order of magnitude higher than thought: "Since I work on rubisco I'm always giving talks saying that it is the most abundant protein on Earth. Sometimes my audience will ask 'Are you really sure?' I can now say 'Yes I am.'" Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a carbon-fixing enzyme found in all photosynthetic organisms. "More than 90 percent of the organic carbon on the planet in form of biomass is the product of the action of rubisco," says Yinon Bar-on from the Weizmann Institute of Science in Israel, who carried out the analysis along with Ron Milo. Forty years ago, biochemist John Ellis declared that rubisco was Earth's most abundant protein. But it turns out that his back-of-the-envelope calculations were off by an order of magnitude. Instead of just 0.04 billion tonnes, plants and marine organisms actually contain 0.7 billion tonnes of rubisco.