Nav: Home

Ratchet up the pressure: Molecular machine exploits motion in a single direction

June 21, 2018

Osaka - Life is driven by molecular machines. Found in every cell, these tiny motors convert chemical energy into work to keep the body moving. The invention of synthetic molecular machines, which perform similar jobs to power miniaturized technologies, is a hot topic in nanoscience.

Now, a team led by Osaka University has invented a ratchet-like molecular machine - a potential component of sophisticated molecular devices - which allows movement in one direction only. This allows the motion and chemical reactivity of a molecular machine to be observed simultaneously, which has been a long-standing challenge.

A classic design for molecular machines is a symmetric "dumbbell" - a large cyclic molecule in the middle, trapped between bulky blockers at each end, linked by a spacer. Inspired by this pattern (known as rotaxane), the Osaka team created a pseudo-rotaxane, where all three parts - the two blockers ("stations") and the central cycle - are small rings. The study was reported in Scientific Reports.

Both stations of their molecular machine are made from pyridinium, a six-membered cycle. Methyl (CH3) groups are attached to each station, like barbed hooks. However, one station carries a single methyl group, while the other end has two.

"This asymmetry sets up an axis along the molecule's length, favoring movement toward the double-hooked end, which acts like a stopper," study first author Akihito Hashidzume says.

The concept was demonstrated by using α-cyclodextrin (α-CD), a macrocycle made of six glucose rings. The α-CD ring is wide enough to fit over the one-hooked end and slide along the ratchet toward the stopper. On the way, it interacts with the stations and the central ring. In fact, α-CD catalyzes a chemical reaction in which the ratchet-like molecule exchanges hydrogen atoms with the water solvent.

Labeling experiments confirmed that this exchange occurred only at one end of the ratchet. When the reaction was carried out in heavy water (D2O), deuterium (D) atoms were found on the methyl groups of the one-hooked station and the central ring as well as on the methylene of the second station, but not the two-hooked stopper. It seems that the α-CD passed over the central ring but was blocked from reaching the methyl groups of the stopper.

"Here we have a chemical reaction coupled with motion biased in one direction," corresponding author Akira Harada says. "We call it 'face-selective translation,' as α-CD prefers to move from one face of pseudo-rotaxane to the other. We take our cue from nature: by ratcheting movement in one direction, we hope to harness chemical energy in a similar way to biomolecular motors, like those in muscles."
-end-
Osaka University was founded in 1931 as one of the seven imperial universities of Japan and now has expanded to one of Japan's leading comprehensive universities. The University has now embarked on open research revolution from a position as Japan's most innovative university and among the most innovative institutions in the world according to Reuters 2015 Top 100 Innovative Universities and the Nature Index Innovation 2017. The university's ability to innovate from the stage of fundamental research through the creation of useful technology with economic impact stems from its broad disciplinary spectrum.

Website: http://resou.osaka-u.ac.jp/en/top

Osaka University

Related Chemical Reaction Articles:

Predicting reaction results: Machines learn chemistry
In the production of chemical compounds, the success of each individual reaction depends on numerous parameters.
Gut reaction: How immunity ramps up against incoming threats
A new study has revealed how the gut's protective mechanisms ramp up significantly with food intake, and at times of the day when mealtimes are anticipated based on regular eating habits.
Chemists glimpse the fleeting 'transition state' of a reaction
Chemists at MIT, Argonne National Laboratory, and several other institutions have devised a technique that allows them to determine the structure of the transition state of a reaction by observing the products that result from the reaction.
The coldest reaction
In temperatures millions of times colder than interstellar space, Harvard researchers have performed the coldest reaction in the known universe.
Immune reaction causes malaria organ damage
Immune cells can be the body's defenders and foes at the same time
Researchers develop chemical reaction method for more efficient drug production
Researchers at Tokyo University of Agriculture and Technology (TUAT) in Japan and Mount Allison University in Canada have developed a more efficient method to produce the building blocks needed for antibiotics and cancer treatment drugs.
Genetics may play a role in reaction to CT contrast agents
Researchers in South Korea have found that patients with family and personal history of allergic reactions to contrast media are at risk for future reactions, according to a new large study.
Rich defects boosting the oxygen evolution reaction
The morphology and electronic structure of LDHs were simultaneously tuned to improve the OER catalytic activity by mild solvothermal reduction using ethylene glycol.
High reaction rates even without precious metals
Non-precious metal nanoparticles could one day replace expensive catalysts for hydrogen production.
Software library to serve for faster chemical reaction processing
Big Data has become ubiquitous in recent years, and especially so in disciplines with heterogeneous and complex data patterns.
More Chemical Reaction News and Chemical Reaction Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.