Details of Photosynthesis Captured by SLAC’s X-ray Laser

The machinery responsible for photosynthesis – while commonplace and essential to life on Earth – is still not fully understood. One of its molecular mysteries involves how a protein complex, Photosystem II, harvests energy from light and uses it to split water into hydrogen and oxygen. This video explains how, in a previous paper, researchers were able to see two key steps in photosynthetic water splitting under conditions as it occurs in nature, a big step to decoding how the process works in detail.

you're probably familiar with

photosynthesis the process by which

plants algae and other related organisms

use light energy to convert carbon

dioxide and water into sugars and oxygen

this incredibly important multistage

process is not only responsible for

providing most of the energy necessary

for life on earth but also for

maintaining the oxygen in our atmosphere

now using the high-energy x-ray laser

pulses produced by SLAC National

Accelerator Laboratories linic coherent

light source

scientists at Lawrence Berkeley National

Laboratory in collaboration with

scientists and slackin Stanford

University and collaborators in Germany

Sweden and the UK have developed a

powerful new way to study exactly how

photosynthesis produces the oxygen that

we breathe these researchers have taken

extremely high-resolution images at

different stages of the process at room

temperature allowing them to search for

how and where the oxygen is produced

under real-life circumstances the

researchers specifically studied the

protein complex photosystem 2 which

produces oxygen from water in a small

region of the protein during

photosynthesis first room temperature

crystals of the protein were introduced

as either a liquid jet or as tiny drops

made using soundwaves

on a moving tape as the crystals move

forward they were hit with pulses of

visible light which triggered different

stages of the photosynthetic process

depending on the number and timing of

the pulses finally the drops were hit by

powerful x-ray pulses from the LCLs by

looking at how the x-ray light scattered

under two different kinds of detectors

the researchers were able to obtain

extremely high resolution structures of

the oxygen producing region of the

protein giving them new insights into

where the bond between oxygen atoms

might form from two water molecules and

where it might not specifically by

watching where ammonia molecules which

are analogs of water molecules bonded to

the region they were able to rule out

some possible locations where the oxygen

bond might form if the ammonia bonded to

a location and oxygen was still produced

then that site was not a likely location

for water or the formation of oxygen

using this and related data the

researchers were specifically able to

raise questions about two of the most

popular locations demonstrating just how

powerful this technique can be while

they haven't found the answer yet the

researchers hope that by continuing to

improve this process and gathering more

and more data at different stages of

photosynthesis they congratulate zero in

on the exact way that oxygen is produced

from water within photosystem two

understanding how this system works

could lead to a revolution in the

development of artificial photosynthesis

solar fuels and more but most

importantly it could finally help us

understand the atomic origins of the

oxygen in the air we breathe every day


Chris Smith/SLAC National Accelerator Laboratory

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