All Enzymes are catalysts, but not all catalysts are enzymes.
Enzymes and catalysts are both involved in speeding up or speeding down chemical reactions within and outside the body. They influence the speed of the reaction without being consumed themselves. Catalysts are either bio-catalysts/ organic (enzymes) or inorganic catalysts (non-enzymatic catalysts).
What are Catalysts?
Catalysts are organic or inorganic compounds that increase or decrease the speed of chemical reactions without being consumed during the process. All biochemical reactions in the body are dependent on catalysts.
The process was first discovered by Gottlieb Sigismund Constantin Kirchhof in 1812 when he observed the breakdown of starch in the presence of sulphuric acid while the acid remained the same at the end of the reaction. Furthermore, the Swedish chemist Jöns Jakob Berzelius named the process “catalysis” in 1835. The name comes from Greek words, “Kata,” meaning down, and “lyein,” meaning loose.
The discoveries regarding catalysis did not end here, and Louis Pasteur discovered enzymes in sugar fermentation which were named by German physiologist Wilhelm Kühne in 1878. Furthermore, various other catalytic processes and enzymes were discovered. Scientists detected that the catalysts are required in small amounts to alter reaction speed. The catalysts elevate or reduce the reaction speed to act as a temporary intermediate product.
As we mentioned earlier, all enzymes are catalysts, but all catalysts are not enzymes. Catalysts are of two types; inorganic and organic. Organic catalysts (enzymes) are discussed below. Let’s tell you about inorganic catalysts.
Inorganic catalysts are transition metals or transition metal oxides. They are typically used to provide a bigger surface area. The increased surface area provides space for the reactions to occur in varying routes, lowering the activation energy. Inorganic catalysts are categorized as heterogeneous or homogeneous catalysts based on the nature of the substance used.
What are Enzymes?
Enzymes are organic catalysts that increase the speed of reaction. Unlike some other catalysts, enzymes do not decrease the reaction speed.
Around 4,000 enzymes and their activities are known so far. Enzymes are proteins produced by living organisms and are composed of 62 to 2,500 amino acids. Enzymes are substrate-specific and catalyze reactions only that are specific to their need. A very small amount of enzyme is needed to catalyze a reaction. They react in mild temperature and pH conditions. Some enzymes also need cofactors or co-enzymes to assist the action. Cofactors are inorganic ions like Mg2+, Zn2+, Fe2+, and Mn2+, whereas co-enzymes are organic molecules.
The structure of an enzyme was thought to be like a key that fits in the substrate. The “Lock and Key theory” proposed in 1894 suggested that the substrate is like a lock and the enzyme fits the substrate that it is supposed to go into – just like a key. After believing in this theory for years, another model called the “Induced fir model” was presented in 1958. This model gives the idea that as the enzymes are protein in nature, they flex and alter their shape a little to fit into the substrate. The site where the enzyme fits the substrate is called the Active site. Enzymes have not only active sites for substrates but also cofactors and others.
Similarities between Enzymes and Catalysts
Besides the fact that enzymes are basically catalysts, there is only one more similarity between the two. Typically, both decrease the activation energy of reactions by providing alternate pathways to the reaction.
Difference between Enzyme and Catalyst
They are either organic (enzymes) or inorganic catalysts involved in speeding up chemical and biochemical processes. They are also categorized as positive and negative catalysts.
Enzymes are usually classified as activation or inhibitory enzymes depending on their function in the body.
Nature of molecule
Catalysts are simple, uncomplicated inorganic compounds.
Enzymes are relatively complex organic molecules.
Catalysts are either small molecules and/or mineral ions.
Enzymes are globular proteins formed by complex structures.
Catalysts are inorganic and thus not synthesized by living organisms.
Enzymes are produced by ribosomes within the body to facilitate biochemical reactions.
Effect on reaction
Catalysts work both ways on a reaction. Sometimes they are involved in increasing the speed of the reaction, while sometimes, they decrease the reaction speed without being consumed during the process.
Enzymes typically speed up the reaction acting as an intermediate and can be obtained in the primary form at the end of the reaction.
Rate of reaction
They usually slow down the processes.
Enzymes speed up the biochemical reactions by several folds.
Catalysts are usually similar in size to their substrate.
Enzymes are large protein molecules and bigger in size than substrate molecules.
Catalysts being inorganic compounds, possess low molecular weight.
Enzymes are organic compounds and thus have higher molecular weight.
Type of reaction
Catalysts usually act on physical reactions.
Enzymes work on biochemical reactions and are a vital part of all reactions within the body.
Temperature and pH
Catalysts can perform at a wide variety of temperature ranges and are not sensitive to minor temperature or pH variations.
Enzymes act in a narrow temperature range, and varying temperature and pH affect their activity. They get denatured at high temperatures and are inactive at low temperatures.
Effect of protein poisons
They are not affected by inorganic catalysts.
Poison proteins can alter the function of enzymes.
Vanadium oxide is one of the examples of catalysts.
Examples of enzymes include lipase, peptidase, etc.
The Bottom Line
Catalysts and enzymes are an integral part of many chemical processes inside and outside the body. Enzymes are organic catalysts that facilitate biochemical reactions through different enzymatic regulations. They are thought to modify their shape slightly for the substrate to attach to the active site for necessary action. Common enzymes present in the body include lipase, DNA polymerase, etc., while metals and metal oxides typically act as catalysts.
Anna has completed her degree in Pharmacy from the University of Hawaii. She is serving as a research assistant in a pharmaceutical company. She had a great interest in writing blogs, traveling to different parts of the US, and trying delicious recipes in her spare time.