Hello steemians. It feels great to be back here again. I've been away from this platform for two months because of the project I was handling. But just like any true lover of science would do, I still created out time to pen down tangible observations from the things I stumbled upon on a daily basis. Actually, I really don't know why I decided to start with this particular topic. Lets just say, anything about biochemistry tickles my fancy. I promise to make this ride interesting and at the same time reach some level of enlightenment which is the primary focus of #Steemstem. 

<h3>Lets start with the basis. What you should know about the crying enzyme</h3>

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<sub> The face you make when the crying enzyme decides to deal with you...  (License: Public Domain]: <a href="https://www.flickr.com/photos/realeyesrealizerealliesxx/7965754376"> 
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In recent times, 'enzyme' is a term that most people are now familiar with. In one word we can say that, *"they are chemical substances whose functions are restricted to living cells"*. Obviously, life would only be an illusion without the action of most of these enzymes in the biological system. As a matter of fact, the primary action that's performed by all enzymes is the **catalysis of specific biochemical reactions**. Funny enough, the current misconception about enzymes, especially by fellows that are not science oriented is that their functions are only peculiar to digestion and absorption of food. However, although digestion and absorption of food seems to be the only phenomenon at the elementary level that elaborate and pinpoint the actions of various enzymes, there are still other numerous biological processes that are enhanced by these catalysts.

As earlier stated, the functions of the enzyme are restricted to living cells. What this means is that, just as enzymes are essential in organisms belonging to the kingdom animalia, their actions are also important in other living things. A typical example we'll be considering in this article is the **Lachrymatory Factor Synthase**. An enzyme present in the onion plant, popularly known as the 'crying enzyme'. This nickname is given to Lachrymatory Factor Synthase mainly because of the defensive mechanism it activates when the onion bulb is being crushed. The resultant effect which is the formation of a volatile fume or gas called the **lachrymatory factor (syn-Propanethial-S-oxide) induces eye irritation, thereby warding off knife-wielding predators (humans) in the process. 

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<sub>  That chemical compound that gets you teary eyed while slicing onions (License: Public Domain]: <a href="https://commons.m.wikimedia.org/wiki/File:Syn-Propanethial_S-oxide_Structural_Formula_V1.svg#mw-jump-to-license"> 
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It might interest you to know that, although humans have been making use of the onion plant for thousands of years now, it's only few years back (2002) that the researchers were able to identify Lachrymatory Factor Synthase (crying enzyme) as the enzyme responsible for the tear-inducing property of the onion bulb. Well, before this time, the volatile fume produced was believed to be triggered by **alliinase**, an enzyme that's present in the fluid sacs of onion cells. According to several scientific researches, immediately an onion is crushed or sliced, these sacs rupture, releasing alliinase in the process. Since alliinase is the enzyme that's released, most researchers accredited the tear-inducing ability of the onions to it. However, the good thing about science is that despite the number of years, a particular knowledge is always open to further analysis to ascertain the validity of such knowledge. 

Inasmuch as alliinase is not the enzyme that triggers the release of the tear-inducing fume when the onion is crushed, it still has an indirect role to play. What happen is that, after the ruptured fluid sacs releases the stored alliinase, it instantly reacts with the amino acids in the onion. The amino acids in this biochemical reaction act as the co-factor resulting in the formation of **sulfenic acid** as the intermediate product. This reaction doesn't end here. For the tear-inducing fume (lachrymatory factor) to be released, Sulfenic acid that is formed must  enter into another reaction aided by the enzyme lachrymatory factor synthase (LFS). It might sound simple, but trust me; the wafting of the lachrymatory factor due to the slicing of onions is a hell of series of complex reactions. 

<h3>With the way individuals suffer while slicing onions, is the crying enzyme really a culprit that should be arrested?</h3>

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<sub>  (License: Public Domain]: <a href="https://www.flickr.com/photos/147425644@N04/29704104160"> 
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Honestly, I love cooking. But the only thing that spoils the fun is whenever it's time to chop those onions. As funny as it may sound, I'm sure alot of people out there can't slice onions without eyeglasses. I can't be the only weird person in this world. Although technological advancement have brought the emergence of various forms of blenders, but still, this can only help to an extent. They're persons like me that love their onions sliced in a particular stylish pattern, especially if they're using it to fry. This is something the blender will definitely not do. So we're only faced with the option of shedding tears every time we cook. 

Because of the irritating effect of the lachrymatory factor to the eye, researchers have been working on ways that they could arrest the crying enzyme from activating it (lachrymatory factor) in the onions. Unfortunately, till date there's no tangible outcome from this prospect. Well, it's not as if researchers haven't tried their best. The truth is, onion is a very difficult biological system to work with and has a poor capacity for manipulation. This is the major reason we're yet to see the evidence of less-tearful and tear-free onions in the market. 

That notwithstanding, it's definitely possible to slice an onion without being affected by its tear-inducing fume. This is achieved if the onion is frozen or sliced while inside the water. Personally, this is actually preferable when considering the methods and techniques used by researchers in improving the tear-inducing fume characteristic of the onion. Since the crying enzyme is the one responsible for the tear-inducing fume, researchers use a specific [gene silencing](https://en.m.wikipedia.org/wiki/Gene_silencing) technology known as RNA interference (RNAi) to arrest or shut down the gene that code for the crying enzyme. The effect of shutting down the lachrymatory factor synthase gene results in the distortion of valuable sulfur pathways. This alteration in the sulfur pathways is believed to diminish the flavor and nutritional value of the onion. Now, the question is, what's the point consuming a tear-free onion with no reasonable health benefits?. You could probably answer that for yourself. 

<h3>Why the tear-inducing onions is still the best option so far...</h3>

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<sub> (License: Public Domain]: <a href="https://commons.m.wikimedia.org/wiki/File:Sistema_lacrimal.gif"> 
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You'll agree with me that although slicing an onion does not always turn out well because of the way lachrymatory factor irritates the cornea of the eye, however, this particular act has a whole lot of physiological benefits that's attached to it. Aside from having a direct link with the savoring flavor and nutritional value of the onion, the wafting of lachrymatory factor in the air aids in cleaning and lubricating the eye. In this part of the world, traditional medicine practitioners encourage individuals not to cover their eyes while slicing onions. According to them, the tear-inducing fumes from onions are essential in eliminating toxins that penetrate into the eyes.

Once again, thanks for doing this with me. Till next time!

<h3>For further reading...</h3>
[This enzyme is why onions make you cry](https://www.smithsonianmag.com/smart-news/researchers-finally-figure-out-onion-enzyme-makes-you-cry-180964325/). Retrieved on the 20th October, 2018
[Silencing onion lachrymatory factor synthase causes a significant change in the sulfur secondary metabolite profile](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2492635/). Retrieved on the 20th October, 2018
[Tearless onion created in lab using gene silencing](https://www.sciencedaily.com/releases/2008/02/080202115345.htm). Retrieved on the 20th October, 2018
 
**<center>Image source</center>**
Images are from flickr and wikicommons, licensed under creative commons and eligible for commercial use.