How Enzymes Work and What is Their Function by Microbiology Doctor dr (doctor-dr)(doctor_dr)
The basics
- Enzymes are proteins that have been folded into complex forms and are found all over the body.
- Enzymes are responsible for the chemical processes that keep us alive - our metabolism.
- Enzymes catalyse (speed up) chemical reactions; in certain circumstances, enzymes may make a chemical reaction millions of times quicker than it would be otherwise.
- A substrate binds to an enzyme's active site and is transformed into products. The enzyme is ready to connect to a new substrate and resume the activity after the products have left the active site.
What do they do?
- The digestive system - enzymes aid in the breakdown of more complex substances such as glucose into smaller ones that the body may utilise as fuel.
- DNA replication - DNA is found in every cell in your body. The DNA in a cell must be replicated every time it divides. Enzymes assist in this process by unwinding DNA coils and copying the data.
- Liver enzymes - the liver is responsible for the breakdown of poisons in the body. It does so by using a variety of enzymes.
The ideal conditions
Enzymes can only function under specific circumstances. Most enzymes in the human body function best when the temperature is approximately 37°C, which is body temperature. They will still operate at lower temperatures, but considerably more slowly.
Enzymes, too, can only work in a specific pH range (acidic/alkaline). Their preferences are determined by their location in the body. Because the stomach is considerably more acidic, enzymes in the intestines function best at pH 7.5, whereas enzymes in the stomach work best at pH 2.
The enzyme changes shape when the temperature is too high or the environment is excessively acidic or alkaline; this affects the structure of the active site, preventing substrates from binding to it - the enzyme is denatured.
Cofactors
Cofactors Some enzymes are unable to operate without the presence of a particular non-protein component. These are referred to as cofactors. For example, carbonic anhydrase, an enzyme that helps the body maintain its pH, can't work until it's linked to a zinc ion.
Inhibition
Enzymes must occasionally be slowed to ensure that the body's systems function properly. For example, if an enzyme produces too much of a product, it must be possible to reduce or stop production.
The activity of enzymes can be suppressed in a variety of ways:
- Competitive inhibitors - a chemical that inhibits the active site of an enzyme, forcing the substrate to compete with the inhibitor for the enzyme's attention.
- Non-competitive inhibitors bind to an enzyme in a location other than the active site, reducing its effectiveness.
- Inhibitors that aren't competitive bind to the enzyme and substrate after they've already bound to each other. The products exit the active site with less ease, slowing the response.
- Irreversible inhibitors attach to an enzyme and render it inactive for the rest of its life.
Enzymes, the largest group of proteins in the body, are chemical catalysts. This means that they help a chemical reaction occur but are not reactants or products them selves. They participate in chemical reactions but are not changed by the reactions. Enzymes act to speed up the rate at which metabolic reactions occur. Nearly 2,000 enzymes are known and each is responsible for speeding up the rate of a very particular and unique chemical reaction
sometimes by a factor of 10 and often by a million or more. No reaction in the body occurs fast enough unless the specific enzymes needed for that reaction are present. These important proteins are able to accomplish their function even when present in very small quantities. This is possible because they are not "used up" in a reaction but remain unchanged to be used again and again as needed. Note how shape is imparent to the function of enzyme molecules. Each enzynie, by eans of its uniquely shaped binding sites, binds to a very specific substance, called a substrate, that it works an-such as a key fits a specific lock. This explanation of enzyme action is sometimes called the lock-and-key mode!.
Enzymes are functional proteins whose molecular shape allows them to catalyze chemical reactions. Subtrates (molecules A and B) are brought together by the enzyme to form a larger molecule (AB).
Specific enzymes examples
The human body contains millions of enzymes; here are a few examples:
- Lipases are a category of enzymes that aid in the digestion of lipids in the intestine.
- Amylase aids in the conversion of carbohydrates to sugars. Amylase is a digestive enzyme present in saliva.
- Maltase is a sugar that breaks down maltose into glucose and is present in saliva. Maltose may be found in a variety of foods, including potatoes, pasta, and beer.
- Proteins are broken down into amino acids by trypsin, which is present in the small intestine.
- Lactase is a digestive enzyme that breaks down lactose, the sugar in milk, into glucose and galactose. It is also present in the small intestine.
- Acetylcholinesterase — in nerves and muscles, this enzyme breaks down the neurotransmitter acetylcholine.
- Helicase is a DNA unravelling enzyme.
- DNA polymerase is an enzyme that converts deoxyribonucleotides into DNA.
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