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  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: permaculture <permaculture@lists.ibiblio.org>, sustagnet@googlegroups.com
  • Subject: [permaculture] How Plants Produce Oxygen Revealed by 'Tour-de-Force' Laser Measurement
  • Date: Thu, 16 Jan 2020 04:25:14 -0500

https://gizmodo.com/how-plants-produce-oxygen-revealed-by-tour-de-force-las-1830285550?utm_medium=sharefromsite&utm_source=gizmodo_facebook&utm_campaign=sharebar&fbclid=IwAR2mM9tNQfhCsxyhb9tdJjSfgHT_c8FBf0224aBIdzVmBkhwGAJYRtbVx6k

How Plants Produce Oxygen Revealed by 'Tour-de-Force' Laser Measurement
<https://gizmodo.com/how-plants-produce-oxygen-revealed-by-tour-de-force-las-1830285550>

[image: image.gif]
Photosystem II splitting water. The blue circles are water, purple is
manganese, green is calcium, red is oxygen. The netting is electrons and
the blue lines are proteins that serve as scaffolding.Illustration: Jan
Kern/Berkeley Lab

An experiment using intense laser pulses has allowed scientists to watch
plants produce oxygen from water part of photosynthesis in real time,
according to a groundbreaking new paper.

Photosynthesis fixes carbon dioxide into sugars and creates oxygen out of
water in the presence of sunlight—it turns the sun into usable energy.
Scientists hope to understand this reaction and incorporate it into solar
energy technology. This new study using one of the world’s brightest lasers
to present a view of the intermediate steps of the reaction—a movie of the
reaction occurring.

“Water splitting is one of the most fundamentally important chemical
reactions on the planet,” Uwe Bergmann, principal investigator at the
Stanford PULSE Institute and a scientist from the paper’s
interdisciplinary, international list of authors, told Gizmodo.

Plants carry out the chemical reactions of photosynthesis using two systems
of proteins, photosystems I and II, held in a part of their cells called
the chloroplasts. Photosystem II was the interest of this study. It uses
light energy to split water molecules, creating electrons and protons used
at other parts of the process. This system also produces the oxygen we
breathe. The water splitting occurs in a part of photosystem II called the
oxygen-evolving complex, where there’s a cluster of manganese, calcium, and
oxygen atoms. Scientist Bessel Kok proposed in 1970 that this region goes
through a series of steps to split water.
[image: image.gif]
The researchers imaged each of these steps by controlling them with light
pulses, according to the paper published today in Nature. It represents an
enormous feat of precision measurement.

Light controls this water-splitting reaction within photosystem II, study
author Junko Yano, from Lawrence Berkeley National Laboratory, explained to
Gizmodo. Studying this oxygen-evolving complex by shining light on it “lets
us capture various moments during the reaction using a sequence of visible
flash lights, and then take ‘pictures’ with x-rays.”

Imaging the oxygen-splitting process in action required first creating
crystals out of photosystem II complexes—this alone was a major feat. The
scientists then had to hit all of the proteins with a pulse of light so
that they proceeded to each of the next steps of the water-splitting cycle
at just the right time. Then, they took the picture by diffracting an
incredibly short x-ray laser pulse off of the crystal. This destroys the
crystallized proteins, but not before capturing the identities of the
molecules and how they’re bonded to one another.

“It’s really a tour-de-force in terms of producing the crystals, giving
them the appropriate flashes, and ending up with these intermediate
states,” Robert Blankenship, a professor in biochemistry at Washington
University in Saint Louis, told Gizmodo. “This is, I think, one of the most
important milestones on this journey to understanding how oxygen is
actually made in these systems.”

The story isn’t over yet. The paper elucidates how photosystem II splits
water, but it leaves out how the molecular oxygen we breathe (also called O2)
forms. Yano told Gizmodo that it was exceedingly difficult to get beamtime
at SLAC National Accelerator Laboratory’s x-ray laser, one of the world’s
brightest.

And there’s more to the story than just understanding plants. “If you
understand how photosynthesis happens, it will be easier to make viable
solar energy panels or something that can sufficiently convert solar energy
to energy we can use,” study author Ruchira Chatterjee, post doctoral
fellow at SLAC National Accelerator Laboratory, told Gizmodo.

Photosynthesis is a marvel—a chemical reaction that evolved early in the
history of our planet, and upon which much of Earth’s life relies. We’ve
just inched another step closer to fully understanding it, and perhaps
harnessing it for our own technologies.

“We need to figure out creating energy without creating carbon dioxide,”
Bergmann told Gizmodo. “You can talk about all kinds of things, but in my
opinion, and in many experts’ opinions, the Sun will be the answer.”
The Plan to Feed the World by Hacking Photosynthesis
<https://gizmodo.com/the-plan-to-feed-the-world-by-hacking-photosynthesis-1715525456>
Cyborg Bacteria Beat Plants at the Photosynthesis Game
<https://gizmodo.com/cyborg-bacteria-beat-plants-at-the-photosynthesis-game-1798314836>
This Could Be the Oldest Photosynthesizing, Sex-Having Organism
<https://gizmodo.com/this-could-be-the-oldest-photosynthesizing-sex-having-1821651562>
To Feed the World, We May Need to Hack Photosynthesis
<https://gizmodo.com/to-feed-the-world-we-may-need-to-hack-photosynthesis-1694078546>

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  • [permaculture] How Plants Produce Oxygen Revealed by 'Tour-de-Force' Laser Measurement, Lawrence London, 01/16/2020

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