Metabolism 101: Enzymes

People talk about enzymes all the time, especially raw vegans. It’s all about making sure that we don’t denature the enzymes in our food or using enzymes to help digest our food. Well, enzymes are about a lot more than that!

Basically, enzymes are biological catalysts. A catalyst is something that will speed up the rate of a reaction. In biology, catalysts are a bit different because they don’t just speed up reactions but actually allow them to happen. Furthermore, enzymes are proteins so our bodies make them based on our genetic blueprint.

Biological catalysts, what does that mean? It means that they will lower the initial energy requirements (activation energy) necessary for a reaction to occur. Remember the post about exothermic and endothermic reactions? Looking at the energy diagrams again you can see that in-between products and reactants there is always a high energy “bump”.  It is the energy investment needed for that reaction. This investment is usually very high and prevents the reaction from occurring. It’s sort of like having to pay a 95% down-payment for a house; it’ll detract anyone from buying it. That’s where enzymes come in because they lower this bump, thus making the reaction possible.

Enzyme activation energy

Enzyme activation energy (Photo credit: Wikipedia)

How do enzymes make reactions happen? It is believed that enzymes provide a space where reactants can come together in a specific orientation. You can think of  them as a conference organizing committee. They will invite important individuals to a specific location, thus facilitating them to come up with ideas. Furthermore, enzymes will have an active site pocket within them where the substrate can enter. That’s where the reaction will occur.

Enzymes are also picky little brats and need very specific conditions to function. A deviation of a few degrees from its optimal temperature could not only stop the reactions but destroy the enzyme. Therefore, yes raw vegans are right in that cooking food will destroy the enzymes in the food. At the same time, enzymes work only at a certain pH with highly basic or acidic conditions destroying the enzyme. For this reason, eating raw food isn’t necessarily better than cooked food. Our stomach is highly acidic, about 10,000 times more acidic then our blood. Hence, most enzymes in raw food will get destroyed in our stomach anyways. It’s important to note that enzymes are not only picky about their working conditions but also their substrate. In general, one enzyme will catalyze one specific reaction. For this reason most enzymes found in raw plants will probably not do anything to us, because they’re meant for catalyzing plant reactions not human ones. Hopefully that dispels some myths 😉

Apart from being able to make reactions occur, they can also regulate them. Think of it, enzymes are proteins which are controlled at the genetic level. Certain stimuli can turn genes on’n’off,  in turn modulating the production of that enzyme. For example, when you sit down to eat a bowl of pasta, your body will increase production of salivary amylase to break down the starch in the pasta. Alternatively, absence of food will do the opposite. 

Most of all, enzymes are crucial for metabolism! They are its driving force and its gatekeepers. This will make a lot more sense in subsequent posts. Stay tuned for aerobic vs anaerobic respiration 😉

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