Biological complexity: enzyme stops U_V damage (Introduction)

by David Turell @, Tuesday, December 05, 2017, 22:09 (9 days ago) @ David Turell

This huge enzyme molecule repairs DNA U-V damage in plants that need to sit in sunshine all day:

"By studying this enzyme, called DNA photolyase, with the ultrabright and ultrafast pulses of the LCLS X-ray laser, researchers finally have the opportunity to watch the enzyme in action as it catalyzes a chemical reaction in real time and at the atomic scale to resolve longstanding debates about how these enzymes work. Ultimately, this knowledge could be used to engineer improved synthetic versions of enzymes that drive crucial reactions in biological systems, or to produce novel enzymes that do not exist in nature.

"'The biochemical reactions performed by enzymes are at the heart of the adaptability and efficiency of living things," says Thomas Joseph Lane, an associate staff scientist at LCLS. "But the details of how enzymes work is hidden in chemical processes that occur on extremely short timescales, down to millionths of a billionth of a second, so we needed LCLS to reveal their secrets."

"In just a few seconds, ultraviolet light from the sun can damage DNA by creating hundreds of unwanted links within DNA's double helix. These modifications make the genetic material bulky and unreadable by DNA replication tools, leading to permanent mutations that can cause cancer and other diseases if left unrepaired.

"But the same sunlight that carries damaging UV rays also contains blue light that can induce photolyase to quickly repair any DNA damage.

"Photolyase is thought to be one reason why plants -- that have hours of exposure to the sun each day -- are less susceptible to UV damage than humans, who lack photolyase. Humans and other mammals must fall back on alternative DNA repair mechanisms (or avoid going out into the sun altogether).


"'There are still some major gaps in our understanding of how enzymes work, highlighted by the fact that human-made enzymes have yet to match nature's performance," says Lane. "We hope our experiments here at LCLS will help us bridge those gaps, getting us closer to understanding and harnessing the chemistry living things do every day.'"

Comment: Note tgeh bold. Our inventiveness is not equal to natures. This study presents the usual problem, how did chance evolution even find this necessary giant molecule? Only design can do this.

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