New study looks to biological enzymes as source of hydrogen fuel

Hydrogen symbol illustration (stock image).

Research from the University of Illinois and the University of California, Davis has chemists one step closer to recreating nature's most efficient machinery for generating hydrogen gas. This new development may help clear the path for the hydrogen fuel industry to move into a larger role in the global push toward more environmentally friendly energy sources.

The researchers report their findings in the Proceedings of the National Academy of Sciences.

Currently, hydrogen gas is produced using a very complex industrial process that limits its attractiveness to the green fuel market, the researchers said. In response, scientists are looking toward biologically synthesized hydrogen, which is far more efficient than the current human-made process, said chemistry professor and study co-author Thomas Rauchfuss.

Biological enzymes, called hydrogenases, are nature's machinery for making and burning hydrogen gas. These enzymes come in two varieties, iron-iron and nickel-iron -- named for the elements responsible for driving the chemical reactions. The new study focuses on the iron-iron variety because it does the job faster, the researchers said.

The team came into the study with a general understanding of the chemical composition of the active sites within the enzyme. They hypothesized that the sites were assembled using 10 parts: four carbon monoxide molecules, two cyanide ions, two iron ions and two groups of a sulfur-containing amino acid called cysteine.

The team discovered that it was instead more likely that the enzyme's engine was composed of two identical groups containing five chemicals: two carbon monoxide molecules, one cyanide ion, one iron ion and one cysteine group. The groups form one tightly bonded unit, and the two units combine to give the engine a total of 10 parts.

But the laboratory analysis of the lab-synthesized enzyme revealed a final surprise, Rauchfuss said. "Our recipe is incomplete. We now know that 11 bits are required to make the active site engine, not 10, and we are in the hunt for that one final bit."

Team members say they are not sure what type of applications this new understanding of the iron-iron hydrogenase enzyme will lead to, but the research could provide an assembly kit that will be instructive to other catalyst design projects.

"The take-away from this study is that it is one thing to envision using the real enzyme to produce hydrogen gas, but it is far more powerful to understand its makeup well enough to able to reproduce it for use in the lab," Rauchfuss said.

Researchers from the Oregon Health and Science University also contributed to this study.

The National Institutes of Health supported this study.

---

Story Source:

Materials provided by University of Illinois at Urbana-Champaign, News Bureau. Note: Content may be edited for style and length.

Study finds dopamine, biological clock link to snacking, overeating and obesity

Clock and eating concept (stock image).

Credit: © nehopelon / Adobe Stock

During the years 1976 through 1980, 15% of U.S. adults were obese. Today, about 40% of adults are obese. Another 33% are overweight.

Coinciding with this increase in weight are ever-rising rates of heart disease, diabetes, cancer and health complications caused by obesity, such as hypertension. Even Alzheimer's disease may be partly attributable to obesity and physical inactivity.

"The diet in the U.S. and other nations has changed dramatically in the last 50 years or so, with highly processed foods readily and cheaply available at any time of the day or night," Ali Güler, a professor of biology at the University of Virginia, said. "Many of these foods are high in sugars, carbohydrates and calories, which makes for an unhealthy diet when consumed regularly over many years."

In a study published Thursday in the journal Current Biology, Güler and his colleagues demonstrate that the pleasure center of the brain that produces the chemical dopamine, and the brain's separate biological clock that regulates daily physiological rhythms, are linked, and that high-calorie foods -- which bring pleasure -- disrupt normal feeding schedules, resulting in overconsumption. Using mice as study models, the researchers mimicked the 24/7 availability of a high-fat diet, and showed that anytime snacking eventually results in obesity and related health problems.

Güler's team found that mice fed a diet comparable to a wild diet in calories and fats maintained normal eating and exercise schedules and proper weight. But mice fed high-calorie diets laden with fats and sugars began "snacking" at all hours and became obese.

Additionally, so-called "knockout" mice that had their dopamine signaling disrupted -- meaning they didn't seek the rewarding pleasure of the high-fat diet -- maintained a normal eating schedule and did not become obese, even when presented with the 24/7 availability of high-calorie feeds.

"We've shown that dopamine signaling in the brain governs circadian biology and leads to consumption of energy-dense foods between meals and during odd hours," Güler said.

Other studies have shown, Güler said, that when mice feed on high-fat foods between meals or during what should be normal resting hours, the excess calories are stored as fat much more readily than the same number of calories consumed only during normal feeding periods. This eventually results in obesity and obesity-related diseases, such as diabetes.

Speaking of the modern human diet, Güler said, "The calories of a full meal may now be packed into a small volume, such as a brownie or a super-size soda. It is very easy for people to over-consume calories and gain excessive weight, often resulting in obesity and a lifetime of related health problems.

"Half of the diseases that affect humans are worsened by obesity. And this results in the need for more medical care and higher health care costs for individuals, and society."

Güler said the human body, through thousands of years of evolution, is hard-wired to consume as much food as possible as long as it's available. He said this comes from a long earlier history when people hunted or gathered food and had brief periods of plenty, such as after a kill, and then potentially lengthy periods of famine. Humans also were potential prey to large animals and so actively sought food during the day, and sheltered and rested at night.

"We evolved under pressures we no longer have," Güler said. "It is natural for our bodies as organisms to want to consume as much as possible, to store fat, because the body doesn't know when the next meal is coming.

"But, of course, food is now abundant, and our next meal is as close as the kitchen, or the nearest fast-food drive-through, or right here on our desk. Often, these foods are high in fats, sugars, and therefore calories, and that's why they taste good. It's easy to overconsume, and, over time, this takes a toll on our health."

Additionally, Güler said, prior to the advent of our electricity-powered society, people started the day at dawn, worked all day, often doing manual labor, and then went to sleep with the setting of the sun. Human activity, therefore, was synchronized to day and night. Today, we are working, playing, staying connected -- and eating -- day and night. This, Guler said, affects our body clocks, which were evolved to operate on a sleep-wake cycle timed to daytime activity, moderate eating and nighttime rest.

"This lights-on-all-the-time, eat-at-any-time lifestyle recasts eating patterns and affects how the body utilizes energy," he said. "It alters metabolism -- as our study shows -- and leads to obesity, which causes disease. We're learning that when we eat is just as important as how much we eat. A calorie is not just a calorie. Calories consumed between meals or at odd hours become stored as fat, and that is the recipe for poor health."

The National Institute of General Medical Sciences and University of Virginia Brain Institute funded the research.

Story Source:

Materials provided by University of Virginia. Note: Content may be edited for style and length.

New study looks to biological enzymes as source of hydrogen fuel

New study looks to biological enzymes as source of hydrogen fuel

Research from the University of Illinois and the University of California, Davis has chemists one step closer to recreating nature's most efficient machinery for generating hydrogen gas. This new development may help clear the path for the hydrogen fuel industry to move into a larger role in the global push toward more environmentally friendly energy sources.

The researchers report their findings in the Proceedings of the National Academy of Sciences.

Currently, hydrogen gas is produced using a very complex industrial process that limits its attractiveness to the green fuel market, the researchers said. In response, scientists are looking toward biologically synthesized hydrogen, which is far more efficient than the current human-made process, said chemistry professor and study co-author Thomas Rauchfuss.

Biological enzymes, called hydrogenases, are nature's machinery for making and burning hydrogen gas. These enzymes come in two varieties, iron-iron and nickel-iron -- named for the elements responsible for driving the chemical reactions. The new study focuses on the iron-iron variety because it does the job faster, the researchers said.

The team came into the study with a general understanding of the chemical composition of the active sites within the enzyme. They hypothesized that the sites were assembled using 10 parts: four carbon monoxide molecules, two cyanide ions, two iron ions and two groups of a sulfur-containing amino acid called cysteine.

The team discovered that it was instead more likely that the enzyme's engine was composed of two identical groups containing five chemicals: two carbon monoxide molecules, one cyanide ion, one iron ion and one cysteine group. The groups form one tightly bonded unit, and the two units combine to give the engine a total of 10 parts.

But the laboratory analysis of the lab-synthesized enzyme revealed a final surprise, Rauchfuss said. "Our recipe is incomplete. We now know that 11 bits are required to make the active site engine, not 10, and we are in the hunt for that one final bit."

Team members say they are not sure what type of applications this new understanding of the iron-iron hydrogenase enzyme will lead to, but the research could provide an assembly kit that will be instructive to other catalyst design projects.

"The take-away from this study is that it is one thing to envision using the real enzyme to produce hydrogen gas, but it is far more powerful to understand its makeup well enough to able to reproduce it for use in the lab," Rauchfuss said.

Researchers from the Oregon Health and Science University also contributed to this study.

The National Institutes of Health supported this study.

---

Story Source:

Materials provided by University of Illinois at Urbana-Champaign, News Bureau. Note: Content may be edited for style and length.