But when they isolated alliinase and mixed it with the sulfoxides, nothing happened. The researchers reasoned that alliinase helped to change the shape of the starter molecule so that the second enzyme could go to work on it. Yet nobody knew for sure. The structure of that LF synthase was unknown. Biochemists study the molecules at work in living things.
Golczak and a team of researchers wanted to know how the eye-irritating LF forms. To do that, they turned LF synthase into a crystal. Now they could use a technique called X-ray crystallography to map its structure. First, the researchers mixed the enzyme with an acid.
This caused crystals to grow in the mixture. The researchers froze the crystals in liquid nitrogen. Then they used a special camera to shoot X-ray beams at the crystals.
When those beams hit the crystal, the X-rays scattered. By measuring the angles of the scattered beams, the researchers could construct a 3-dimensional picture of the enzyme. From this, they made a model of what the enzyme looks like.
Block calls the new study the next logical step in solving a longstanding question. Understanding the structure and function of enzymes is a complex science. Although LF synthase was identified as early as , until now, no one has been able to show how it actually works. Golczak and his colleagues turned solutions of the enzyme into microscopic crystals, which they were then able to visualize using X-rays. This allowed them to determine the 3-D structure of the enzyme and identify the small pocket in which the chemical conversion of LF takes place.
Detailed knowledge of this chemical process fills a fundamental gap in knowledge and gives scientists a better understanding of the biochemical potential of onions.
Onions have a wealth of health benefits. Studies suggest a link between the chemicals in onions and the inhibition of cancer growth, as well as improvement of sleep and mood. As they are also a very good source of dietary vitamin C, which is a building block of collagen , onions may well play a role in hair and skin health. To save us from the discomfort of tears, two groups of scientists have already been working on producing tear-free onions.
One of these new onions has been shown to inhibit platelet aggregation, which is associated with cardiovascular disease. The next time you are getting your chopping board ready to whip up a meal full of healthful onions, think of the amazing biochemical processes that will unfold in front of your teary eyes.
Burning eyes refers to stinging or irritation of the eyes. This symptom can be uncomfortable and concerning, but it is treatable. Learn about the…. A chalazion is a small, painless lump that can develop on the eyelid. They usually heal on their own in a few weeks without treatment. What are some common eye problems? Read on to learn more about common eye conditions and tips to help prevent vision loss.
Some people are more likely to cry when cutting onions than others. The onions that generate the harshest chemical reaction have lots of sulfur-containing compounds. These include yellow, red, and white onions. Sweeter types, such as green onions , have less sulfur, are less pungent, and produce fewer tears in most people.
Through genetic transformation, crop scientists have also created tear-free onion varieties. While not yet mass-produced, you can find tear-free onions called Sunions in some specialty markets. Here are some tips to reduce crying from onion irritation:. First, keep in mind that the length of time you store onions affects their potency and tear-producing abilities. Fresher onions are less likely to cause crying than those that have been stored for an extended period of time.
However you slice them, try to avoid cutting your onion near the root end. This is the part that contains the highest concentration of sulfuric compounds that can make you cry. Using a sharp knife may also help. The sharper the knife, the less damage is done to the onion, and fewer irritations are released into the air as a result. To reduce or eliminate onion tears, you may have the best luck if you diminish the sulfuric acid compounds in the onion itself.
To do this, try chilling your onion in a bowl of ice water for 30 minutes before cutting. Some people also prefer to cut their onions while submerged in cold water. Try running a fan to circulate the air or wearing eye protection, such as goggles, while you prepare onions. One old tale says to keep a piece of white bread in your mouth while cutting, based on the theory that the bread will absorb onion vapor. The distinctive taste of fresh onion can be hard to replicate.
But you may want to substitute onions in your cooking if they frequently cause uncomfortable, disruptive eye symptoms. Preparing onions often causes a chemical reaction that results in tears for most people. Some people are more sensitive to onions than others. White, yellow, or red onions are also more likely to make you cry than green ones. Sweeter onions are gentler on the eyes than those with a more pungent taste.
0コメント