Catalysts 7/1/19

By Richard Bleil

Let’s take a few minutes to discuss catalysts. I’ve always like catalysts, and are often found being chased by dogalysts.

That was like a joke. Just smaller.

One of my pet peeve phrases is “heat catalyzed”. Heat is not a catalyst; it really can’t be. By definition, a catalyst is a chemical that speeds up a chemical reaction but is not consumed by it. In other words, reactions run faster by the presence of a catalyst, but the amount of catalyst never decreases.

You own catalysts. Yuh huh. YUH HUH! Probably one of the best known catalysts is the “catalytic converter”. I have one on my car, but it’s still not a Cadillac. Part of the exhaust system, the catalytic converter converts carbon monoxide to carbon dioxide. It’s made of strips of platinum (and, yes, there are catalytic converter thieves for this very reason), so it’s fortunate that it is not consumed in the reaction as that could become very expensive very quickly.

Catalysts act by providing a new reaction pathway. Without a catalyst, for the reaction to occur a carbon dioxide molecule would have to collide with an oxygen molecule in the correct orientation (that is, the oxygen has to hit the carbon side, not the oxygen side) and energy. In the presence of platinum, however, the oxygen of a carbon monoxide will form a bond with one of the atoms of platinum, leaving the carbon sticking up. With the carbon monoxide in one fixed location, and the carbon already in the correct orientation, it’s far easier for the molecule to find an oxygen with which to react. Once the carbon monoxide reacts and becomes carbon dioxide, it releases from the platinum and continues on its merry way.

The same reaction, the same reactants, the same products, but it reacted in a different way. And, because the platinum is released in the end, it is still there to react again. The amount of platinum never decreases.

This is why “heat catalyzed” is a misnomer. Another thing about catalysts is that they only work on a reaction that would occur on its own anyway. They can speed up reactions, but can’t cause them. For example, all peroxides are unstable, and hydrogen peroxide will break down on its own into water and oxygen. However within our bodies is an enzyme called “peroxidase” that breaks down peroxides. That’s why hydrogen peroxide bubbles when it comes in contact with blood. The peroxidase enzyme dramatically increases the rate of decomposition of hydrogen peroxide causing oxygen bubbles to form rapidly.

So, you might think, this is supposed to be about catalysts not enzymes. Enzymes are actually organic catalysts made of the same amino acids as proteins. These enzymes are encoded in our DNA, and because they are like miniature proteins, they have to follow the same rule as proteins to function properly. They must be correctly “folded” (that is, they must be in the correct shape) to work. Heat, acid and other conditions can cause the enzymes to denature or “unfold”, and they no longer work. An example of such denaturation is the protein albumin, the primary ingredient in egg whites. To function, it is a clear colorless liquid, but when heat is applied, as in when we cook the egg, the albumin denatures and becomes a white solid.

Enzymes are all catalysts, and named after their function with an -ase added to the name. Peroxidase catalyzes peroxides, and hydrolase hydrolizes sugars. Another example of such enzymes is found in “Bean-o”. Beans contain complex carbohydrates that our body does not break down naturally, causing them to break down in our intestines rather than the stomach, resulting in the production of hydrogen sulfide gas and methane. Soaking beans in water reduces this problem because the complex carbohydrates break down in the presence of water naturally, but adding hydrolase the the food allows this to occur more rapidly.

Enzymatic (that is, catalytic) activity is critical to both life and death. One of the deadliest natural poisons is the venom of the brown recluse spider. The venom contains a catalyst that speeds up decomposition of flesh. Because it’s a catalyst, it will act to break down tissue, but will not be consumed in the process. This is why such a small amount (let’s face it; these spiders are not very large) can spread. As it is reacting, it just keeps traveling. What starts as what appears to be a minor skin lesion eventually grows into a hole, and left untreated, the enzyme can get into the blood and attack internal organs such as the heart.

And here I am, hoping to sleep tonight.

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