40 | New Scientist | 5 March 2022

    

 

   

   

The warming of our planet is

usually blamed on carbon dioxide,

but there is another major

greenhouse gas contributing to the

havoc in our skies too: methane.

There is far less methane being

emitted into the atmosphere than CO2 , but

during its first 20 years there, methane’s

warming effect is more than 80 times greater.

As it is emitted from livestock and leaky

pipes, methane also reacts with nitrous

oxides to make the gas ozone close to Earth’s

surface. Here, ozone causes people breathing

problems and is linked to a million premature

deaths globally each year.

If we could scrub the air of methane, it would

help stop temperatures rising, buying us some

time to reduce our other carbon emissions. For

every billion tonnes of methane removed from

the atmosphere, Earth’s surface temperature

would be reduced by a roughly 0.2°C, according

to recent estimates from Rob Jackson at

Stanford University in California and his

colleagues. “It’s not easy, but if we can work

out the chemistry, I think it’s a fantastic

opportunity,” says Jackson.

Technologies for capturing CO2 have been

around for years. The gas given off in power

station flues can be trapped by binding it to

machine that could drill through cell

membranes. This allows it to open holes

through which drugs could be delivered.

Such devices can be built on to create

even more sophisticated machines. The

potential is huge: after all, living things

use biomolecular machines to do many

useful jobs. Ribosomes, for example, are

biomolecular machines that assemble

proteins. They add molecules called

amino acids together in specific

sequences to create a vast array of

amazing materials, from the keratin

in fingernails to the disease-busting

antibodies of our immune systems.

David Leigh at the University of

Manchester, UK, has long been working

on a synthetic version of the ribosome.

His designs tend to be based on a

ring-shaped molecule equipped with

an “arm” that moves along a linear

molecular track, picking up pieces along

the way and joining them together.

Last year, Leigh and his team linked

two of these machines together so they

could build a peptide with 10 amino

acids, in a specific sequence.

For the moment, Leigh’s machines

can’t go beyond what nature can do.

But that could change. Ribosomes

only build with about 20 amino acids,

but a synthetic ribosome could be

designed to work with a far wider

range of molecules. “We can use the

whole of the periodic table,” says Leigh.

“I think molecular machines are going

to change how we do everything in

terms of material design.”

 

 



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