Introduction
[License: Public Domain]:
Pixabay Basically everything in life has an orchestrator. The reason why those at the south pole or even at the western or eastern regions of the globe do not just fall off into space is gravity (or maybe, we just have sticky feet lmao). It sort of keeps us glued to the earth. It is also the same reason why when you throw a ball up, you can keep your hands open hoping to catch it knowing it will come down. Gravity yet again gave you that assurance. Without the mitochondria, cells will not be able to generate energy for their day to day activities. They will eventually die because energy is indispensable and essential for the survival of living organisms. Let me say there are guys, predominant in nature, who do a lot of work behind the scenes but take little or no credit for it. In biochemistry, I know a group of those guys. They are called Enzymes
Let Us get To Know These Guys Who Do Most of the Biological Work and Get Little Recognition.
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Pixabay Let me take you down a certain path of realization. You are a multicellular organism. Okay, this means that you are basically just a mash up of cells which happens to be organized well giving you as the overall product. You continuously synthesize cool molecules which you need and well, you are not set up like a factory (literally !). You also breakdown complex stuff like the tough carbohydrates (starch) and get what you survive on (glucose) from them but you are not set up like a machine that breakdown stuff. This apparently means that there is perhaps something which has conferred on you this ability.
This is no voodoo or magic. You just happen to have a couple of cool guys known as enzymes. I can give you some credit because you make these guys anyway. These cool guys are proteins. We however have a few which are not proteins. Just a few. So I can still say enzymes are proteins and sound politically correct. Whatever. I do not seek political correctness. I want to remain as factual as possible. So, most of these cool guys are proteins. A few are not. So what are they ? RNA molecules actually. Yeah, an example is the Ribozyme which can pretty much what protein containing enzymes can. Okay so now you know there are cool guys that give you special abilities like digestion, biosynthesis and breakdown and what not. Let us proceed to knowing what they look like.
What Do These Cool Guys Look Like anyway ?
[License: CC-BY 4.0, Author: Thomas Shafee]:
Wikicommons Enzymes are proteins so they are gonna look like proteins. They are made up of amino acids arranged in sequences as regards the particular enzyme. These amino acids need to be arranged pretty much well as encoded in the RNA transcript so as to maintain the cool property (catalytic activity) of the enzyme. They are mostly synthesized in their proactive forms. In this form, they are known as zymogens or proenzymes. They are activated when needed either by cutting off some parts of them (these parts block their catalytic abilities by some mechanism), a process known as cleavage. Having enzymes in their inactive form and activating them when needed has proven time and time again to be very crucial.
It is the reason why trypsin which acts on proteins can be produced by the pancreas exported to the small intestine without eating up (digesting) the pancreas. The inactive form (trypsinogen) moves to the small intestine to be activated only when necessary.
So I have established that enzymes are produced and maintained in their inactive forms. Well, they also have special compartments in them that need to bind to what is referred to as substrates. They bind to substrates and find the easiest way to transform them (they find the easiest route for a reaction to follow). Those special compartments are referred to as active sites and they are peculiar to each enzyme. It is therefore of no wonder why there are lot of these cool guys (way more than a thousand).
These cool guys are also specific in their action. In that they stick to one mate. Actually, they bind specific substrates so it’s difficult to see an enzyme possessing the ability to bind two or more different substrates interchangeably. Trypsin will bind to proteins and nothing else. Glucokinase will bind to glucose and nothing else.
What They Do and How They Do It
[License: CC-BY-SA 3.0, Author:Aejahnke]:
Wikicommons Enzymes are catalysts and well, that only implies they speed up already existing reactions. Just like catalysts, they remain the same, as they were in the beginning of the reaction, at the end of the reaction. This means that they are not a part of the reaction but influence the reaction from the sidelines.
Enzymes speed up biological reactions by lowering their activation energies. The activation energy is what needs to be overcome before a reaction can take place. Without an enzyme, the activation energy stays the same and some external factors like heat or pressure or both needs to be applied for the activation energy to be overcome and this will take a lot of time as well as energy. This is not thermodynamically favorable and also a huge waste of energy.
With enzymes however, the activation energy is lowered and the reaction can proceed easily and on time. This makes enzymes very important because technically, they speed up reactions. It is the reason you can, after being hungry for hours and feeling so weak, eat food and feel strong again within just minutes. Your digestive reactions are sped up. Thanks to enzymes really.
Death Comes in Threes, Enzymes Come in Classes
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Pixabay Just as there are different classes of reactions in biological systems, there are different classes of enzymes. I mean come on, you don’t expect an enzyme that catalyzes an isomerization reaction to catalyze an oxidation-reduction reaction. So the varieties of reactions have given rise to the different classes of enzymes.
The first class of enzymes are the cool oxidoreductases. These guys alter the oxidative states of molecules as they wish. I mean they increase the oxidative state of one molecule while simultaneously reducing the oxidation state of another. Cool stuff. A basic knowledge of chemistry will tell anyone reading this that oxidation has to occur in tandem with reduction. It’s more like adding something here and reducing something there to keep everything in check. This is to make sure that equilibrium is maintained as true catalysts (enzymes being one) do not alter equilibrium. An example is Malate dehydrogenase which can catalyze the addition of oxygen (oxidation) and removal of oxygen (reduction) to fumarate yielding malate and fumarate respectively.
The next class of enzymes just like take to stuff from one person and give it to another person. They are known as the transferases. They orchestrate the movement of a group from a molecule to another. An example is hexokinase seen in the first step of glycolysis which catalyzes the transfer of a phosphate group from ATP to glucose.
The next class of enzymes are those merchants that like to use water to break chemical bonds. They simply split bonds and place water between them so the bonds do not form again on their own. They are known as the hydrolases. Phosphatase which removes phosphate groups from molecules is an example of a hydrolase.
The next guys like to insert double bonds rather than break them. They just simply take out a functional group and add a double bond at that spot. They even go ahead and add groups to double bonds. They just don’t break bonds. They are known as Lyases. Deacetylases and decarboxylases are typical examples.
The next guys like to tweak molecules producing alternative structures of them. They are known as the isomerases. They move groups around on molecules producing isomers of these molecules. An example are the epimerases which convert glucose to galactose or mannose as the case may be.
The last guys are more like priests or imams as the case may be. They like to join molecules (in matrimony ? Lol) producing bonds (maybe till death do they part). They are known as the ligases. An example is Acetyl CoA Carboxylase.
What Do Locks and Keys Have in Common with Enzymes and Substrates ?
[License: CC-BY-SA 3.0, Author:Jcliang]:
Wikicommons Well, just like a key always has to fit perfectly with a lock for a door to be successfully opened, a substrate needs to fit perfectly with an enzyme for a reaction to take place. It is however stupid or ignorant to see an enzyme as a lock and a substrate as a key as they do not stay unchanging like locks and keys. Substrates and enzymes change conformation upon binding making a reaction to go through (the induced fit model). This is in opposition to the lock and key model of enzyme-substrate binding where the enzyme structure is assumed not to change but stay constant binding only to tailor made substrate. This is clearly not the case as there is always a change of conformation after binding.
Yeah, Speeding Up Our Reactions is Cool but Do We Always Need To ?
[License: Public Domain]:
Pixabay No, we do not always need to. Reactions only need to take place when necessary. So enzymes have to somehow be tamed. This gives rise to the concept of inhibition. Competitors can bind to the active sites of enzymes preventing their substrates from binding and making sure reactions do no proceed. This has been hijacked by clinicians and pharmacists enabling the designing of drugs that can act as enzyme competitors preventing certain reactions from taking place. Non-competitive inhibitors bind to a site other than the active site of an enzyme meant for the substrate and prevents a substrate from binding by mostly inducing a change or changes in the active site of the enzyme.
Enzymes can also be regulated by attaching to or removing functional groups from an enzyme which alters the activity of the enzyme. A process known as covalent modification or they can just kept in their proactive form and activated when necessary. Anything works ;).
Are Enzymes just Useful in Biological Systems ?
[License: Public Domain]:
Pixabay No. Enzymes have wide applications outside the biological system. They are particularly seen in industries and in clinical practices. How do you think cheese is made ? Using enzymes like Rennin and Lipase. How do you think detergents are so effective ? Thank the lipases, professed and amylase. How do you think recombinant DNA is made ? Thank the restriction endonucleases, DNA ligases and DNA polymerases. How do you think biomass is pretreated for biofuel production ? Thank the ligninases. How do you think beer is brewed ? Thank the amylases and professes again. How do you think bread is whitened ? Thank the lipoxygenases. The industrial applications of enzymes are very numerous.
Enzymes can also act as markers of diseases. Finding creatine kinase- MM (found exclusively in the muscles) in blood could be indicative of internal muscle injuries. Finding creatine kinase-MB (goofy exclusively in the heart) could be indicative of a heart disease. This is just one of the cases where enzymes play a role in clinical practice. There’s a whole lot of them, trust me.
Final Thoughts
Enzymes are the molecular workaholics of biological systems and show a particularly amazing diversity. They speed up biological reactions making life possible and also aid in the synthesis of molecules required for survival. They do not get enough recognition but at least they got some today ;).
References
Moore, J. T and Langley, R. (2008). Biochemistry For Dummies. Wiley Publishers. pp. 85-111. Image Sources I'm a proud member of the steemstem community which promotes quality posts in the science, technology, engineering and mathematics fields on the steem blockchain mainly through interaction and engagement. Feel free to join us on discord here
Enzymes.
Lehninger, A. L., Nelson, D. L., & Cox, M. M. (2000). Lehninger principles of biochemistry. New York: Worth Publishers. pp. 190-238
Chatterjea, M. N. (2012). Textbook of Medical Biochemistry. (8th Edition). Jaypee Brothers Medical Publishers. New Delhi. India. pp. 139-153.
All images are licensed under creative commons and eligible for commercial use.
Each time I remember these..... I call those guys geniuses
Secondly, I will like to inform you that you have just helped me to summarise part of my topic in chemical pathology.
This is explicit and detailed.
Brilliant!
Thanks for the thoughtful comment man. I’m glad you again found this useful 😛
Good lesson and well explained.
I've always found it difficult to explain to laymen about the role of enzymes (in general). I explain that they are proteins, and they facilitate ("catalyze") chemical reactions. In my experience it is difficult to convey the mechanism (if known), or even the general concept of enzyme catalysis via assisting chemical bond transitions--once an interested inquirer associates "enzyme" and "protein," those preconceived notions of "nutrition" and "dietary intake" distract from my attempts to explain reaction mechanisms and thus seem like irrelevant concepts. It's much easier to talk nerdy to fellow scientists, but laypeople in general have seen too many TV commercials butchering our terminology.
Hello @kingabesh
Very all-encompassing article on enzymes, how they interact with given substrates to enhance biochemical processes, their specificity and applications in both biological and nonbiological systems. Enzymes are just indispensable!
Very rich article
Regards
@eurogee of @euronation and @steemstem communities
I've been doing some work on biofuel production for a while now and this never occured to me.
Thanks so much man @kingabesh, definitely an interesting read too.
You’re welcome man
Hi @kingabesh!
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Guy I won't lie to you, you are a beautiful mad genius 😂. You sure know how to glue our legs on your post or do we have a sticky mind too? 😂
I learnt slot regarding the AuxiriboNucleicAcid here. I am not a Biology dude but I love this. Keep STEMING @kingabesh! Chop kisses 😘 😘
I am @teekingtv and I write STEM.