---
title: "The most abundant protein on Earth"
url: https://plants.lasse.co.uk/fact-archive/the-most-abundant-protein-on-earth/
---

# The most abundant protein on Earth
Date: 2026-06-14

Rubisco is an essential protein used in photosynthesis to fix atmospheric CO2 into sugars, and it's often claimed to be the most abundant protein on earth. It has been estimated that there are 5 kg of Rubisco per person on Earth. However, Rubisco is also an infamously slow and inefficient protein, prone to fixing O2 instead of CO2 hence why some plants have evolved special mechanisms to improve carbon fixation by Rubisco.



## References:

1. [There are 5 kg Rubisco per person on Earth!](https://www.pnas.org/doi/full/10.1073/pnas.0907732106)

1. [3% of the leaf weight is Rubisco](https://www.pnas.org/doi/10.1073/pnas.1816654116)





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