Key Takeaways

Plain English Takeaway

Scientists changed a natural protein so it could help living cells make new types of silicon-based chemicals, something nature never did before.

Study Aim

The study set out to create an enzyme (a protein that speeds up chemical reactions) that can form bonds between carbon and silicon atoms. The authors wanted to show that it is possible to use directed evolution (a method for improving proteins by making and selecting mutations) to give living systems the ability to make organosilicon compounds, which are not found in nature. Simply put: The researchers wanted to make a protein that lets living things build new silicon-containing chemicals.

Study Design

The researchers tested whether heme proteins (proteins containing an iron-based molecule called heme) could help join carbon and silicon atoms together. They started with cytochrome c from the bacterium Rhodothermus marinus and used directed evolution, introducing mutations to improve its ability to form carbon–silicon bonds. They screened different protein variants in bacteria and measured how well each one made organosilicon products, both in test tubes and inside living cells. Simply put: The team changed a bacterial protein step by step and checked if it could help make new silicon-based chemicals.

Findings

The study demonstrates that the evolved cytochrome c enzyme can efficiently and selectively form carbon–silicon bonds, producing a wide range of organosilicon compounds as single mirror-image forms (enantiomers). The best mutant worked over 15 times better than the best chemical catalysts and could do the reaction inside living E. coli cells. The enzyme tolerated many different starting materials and worked under mild, environmentally friendly conditions. This work shows that proteins can be engineered to create new types of chemical bonds not found in nature, opening up new possibilities for making useful silicon-based molecules. Simply put: The improved protein made many new silicon-containing chemicals quickly and cleanly, even inside living bacteria.

Abstract

Enzymes that catalyze carbon-silicon bond formation are unknown in nature, despite the natural abundance of both elements. Such enzymes would expand the catalytic repertoire of biology, enabling living systems to access chemical space previously only open to synthetic chemistry. We have discovered that heme proteins catalyze the formation of organosilicon compounds under physiological conditions via carbene insertion into silicon-hydrogen bonds. The reaction proceeds both in vitro and in vivo, accommodating a broad range of substrates with high chemo- and enantioselectivity. Using directed evolution, we enhanced the catalytic function of cytochrome c from Rhodothermus marinus to achieve more than 15-fold higher turnover than state-of-the-art synthetic catalysts. This carbon-silicon bond-forming biocatalyst offers an environmentally friendly and highly efficient route to producing enantiopure organosilicon molecules.

Referenced In

StarTalk Show Notes

24 days ago

StarTalk

Season 17, Episode 27: Could There Be Silicon-Based Life?

Hey StarTalkians! In season 17, episode 27, Neil and Chuck sat down with astrobiologist and bacteriology professor Betül Kaçar to talk about the origins of life and astrobiology. Towards the end of the interview, they discuss a topic that will be familiar to any sci-fi fans: the possibility silicon-based life.

How Did Life Begin? with Betül Kaçar - StarTalk Radio

(from 52:57)

One of the most memorable examples in fiction are the rock creatures from Star Trek’s “The Devil in the Dark”, but is such a thing really possible? Dr. Kaçar implied it was, but they didn’t have time to go into much detail, so here’s the whole story.

Why Silicon?

As explained on the podcast, the main reason people take the idea of silicon-based life seriously is because of its similarity with carbon. It’s in the same group of the periodic table, which means it has the same valency as carbon. As Neil explains, this is basically saying it has the same outer electron configuration.

This means – theoretically – it could produce a similar range of compounds, with silicon taking carbon’s place as a “scaffold” for complex chemical structures. A 2020 paper goes into this in detail.

The Problems with Silicon

Many discussions of this topic breeze past a few substantial issues for the sake of the Trek-style thought experiment. Firstly, and most importantly for “life as we know it,” silicon-based compounds are often vulnerable to hydrolysis, so they can’t survive for long in water.

The argument about valency also misses some detail. Yes, silicon can make the same number of covalent bonds as carbon, but a fully-bonded carbon atom has a full outer electron orbital, while silicon doesn’t. Silicon bonds are also more strongly polarized than carbon bonds, and these factors combined leads to some different behavior.

Silicon-Based Molecules Can Work

As Dr. Kaçar describes, scientists have had some success in making silicon-based organic molecules using enzymes, and other researchers have incorporated silicon-carbon bonding into amino acids. This is why the theory still seems solid, despite some issues.

Life, But Not as We Know It

Shockingly, silicon-based molecules tend to be more stable in sulfuric acid than in water, and could have an advantage over carbon in hot environments. So while Earth-like environments aren’t ideal, silicon-based life could be found on a Venus-like world we’d consider uninhabitable.

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Created: May 5, 2026