Amazing Enzymes and Where To Find Them

Reading Time – 6 Minutes, Difficulty Level – 2/5

The reason we have cheese, and the reason most of us can’t eat it

Did you know that approximately 68% of people worldwide can’t digest cheese and other dairy products? It turns out that the inability to digest the sugar (lactose) in milk is the default state for humans. So, if you can indulge in dairy without running to the restroom, you likely harbor a mutation in your LCT gene. LCT is just one of the 5000 genes responsible for producing enzymes—proteins that speed up chemical reactions in our bodies (hint: their names often end in -ase). For instance, the LCT gene is responsible for lactase, lipase that breaks down lipids, and carbohydrase—well, you can guess that one. Enzymes can also be extracted from animals and are important in manufacturing food for bread, juice, yogurt, cheese, and much more. But their story doesn’t end there.

Nucleases and the Fine Art of DNA Repair

Every day, our cells undergo a staggering 2 trillion cell divisions. With each division, a cell must meticulously double all of its organelles, including mitochondria, Golgi bodies, and replicate all the DNA in its nucleus. This replication process involves DNA polymerase, an enzyme tasked with creating new DNA strands that faithfully match the originals. But with such a colossal number of replications happening daily, it’s inevitable that polymerase will occasionally slip up. Studies estimate that DNA polymerases make errors roughly once every 104–105 DNA bases added during replication. This means that with each cell division, around 100,000 polymerase errors can occur. A correction mechanism at near 100% efficiency is necessary to prevent harmful mutations.

Enter nucleases, the unsung heroes of DNA replication. Nucleases are enzymes specialized in breaking down bonds of misplaced DNA bases, allowing polymerase to swoop in and rectify its mistakes. Endonucleases, for example, target errors nestled within the DNA strands by cleaving the bonds within the strand, creating breaks that signal the damaged section for repair. Exonucleases, on the other hand, focus on correcting mistakes at the ends of the DNA strands, effectively “proofreading” the DNA sequence before the cell proceeds with replication.

Together, these enzymes form a meticulous repair system. Without them, the accumulation of errors could lead to a cascade of mutations, potentially resulting in genetic disorders or even cancer.

Digestive Enzymes: Let’s Break it Down

A common misconception is that digestion starts at the stomach, but the truth is, it begins the moment we take our first bite. Amylase, an enzyme found in our saliva, kicks off carbohydrate digestion in the mouth by breaking down complex starch molecules into simpler sugars like glucose and maltose. This process is essential for converting carbohydrates into a form that our bodies can absorb and use for energy.

Next is where proteases come into play. Unlike amylase, these specialized enzymes thrive in the acidic environment of the stomach, where they break down complex protein structures into smaller peptide fragments. One of the most well-known proteases is pepsin, which is produced by the stomach lining and activated in the presence of hydrochloric acid. Pepsin cleaves proteins into shorter peptide chains, setting the stage for further breakdown in the small intestine.

Meanwhile, lipases, another group of digestive enzymes, break down fats into fatty acids and glycerol. These lipid-digesting enzymes are produced by the pancreas and released into the small intestine

So, next time you see someone reaching for a digestive enzyme supplement, you’ll know that it’s actually amylase, lipase, and protease that’s in there, working together to ensure efficient digestion and nutrient absorption.

Can you say Hyperphenylalaninemia 3 Times Fast?

Hyperphenylalaninemia may sound like a mouthful, but it’s simply a condition where there’s an excess of the amino acid phenylalanine in your bloodstream. This can lead to a condition known as PKU. The culprit? A missing or insufficient enzyme called phenylalanine hydroxylase, whose job is to convert phenylalanine into another amino acid called tyrosine. Without enough of this enzyme, phenylalanine accumulates in the blood, causing potential issues for brain and nervous system function.

Fun fact: PKU is one of the first health checks performed on newborns. Yep, right after you were born, a tiny blood sample was likely taken from a small prick on your heel to assess your phenylalanine levels. If the test comes back positive, it’s crucial to act swiftly. Delaying treatment beyond the first few weeks of life can have significant consequences for brain development.

When it comes to treating PKU, the focus is on managing phenylalanine levels through dietary modifications. This often involves following a special low-protein diet, which limits foods high in phenylalanine such as meat, fish, eggs, dairy, nuts, and certain grains. Instead, individuals with PKU may rely on specially formulated medical foods and supplements that provide the necessary nutrients without excess phenylalanine.

It’s worth noting that treatment protocols may vary depending on the individual’s age, severity of the condition, and other factors. But with careful management and adherence to treatment guidelines, many individuals with PKU can lead healthy and fulfilling lives.

From breaking down the food we eat to ensuring our DNA is replicated accurately, enzymes are quietly doing all the heavy lifting to keep our bodies running smoothly. Recognizing their importance deepens our understanding of the important mechanisms that support our health and well-being. How does this change your perspective on the small but essential processes that keep us alive? As we explore the biological systems within our bodies, we realize that sometimes, the most profound discoveries lie not in the world around us, but within ourselves.

References

• ^{Brown, C. S., & Lichter-Konecki, U. (2016). Phenylketonuria (PKU): A problem solved? Molecular genetics and metabolism reports, 6, 8-12.}
• ^{Hatton, I. A., Galbraith, E. D., Merleau, N. S., Miettinen, T. P., Smith, B. M., & Shander, J. A. (2023). The human cell count and size distribution. Proceedings of the National Academy of Sciences, 120(39), e2303077120.}
• ^{Hosfield, D. J., Mol, C. D., Shen, B., & Tainer, J. A. (1998). Structure of the DNA repair and replication endonuclease and exonuclease FEN-1: coupling DNA and PCNA binding to FEN-1 activity. Cell, 95(1), 135-146.}
• ^{Mądry, E., & Fidler, E. (2010). Lactose intolerance–current state of knowledge. Acta Scientiarum Polonorum Technologia Alimentaria, 9(3), 343-350.}
• ^{Tymoczko, J.L., Berg, J. M., Gatto, G.J., and Stryer, L. (2019) Biochemistry: A Short Course, 4th Ed., w.h. freeman, Macmillan Learning, NY}