What Are Enzymes?
Substances that speed up chemical reactions are called catalysts. Organic catalysts are called enzymes.
Enzymes are specific for one particular reaction or group of related reactions.
Many reactions cannot occur without the correct enzyme present.
They are often named by adding "ase" to the name of the substrate. Example: Dehydrogenases are enzymes that remove hydrogen.
The shape of the enzyme must match the shape of the substrate. Enzymes are therefore very specific; they will only function correctly if the shape of the substrate matches the active site.
Enzyme and substrates
An enzyme-substrate complex forms when the enzyme’s active site binds with the substrate like a key fitting a lock.
The product is released from the enzyme. The enzyme can be reused.
Enzyme and product
The substrate molecule normally does not fit exactly in the active site. This induces a change in the enzymes conformation (shape) to make a closer fit.
In reactions that involve breaking bonds, the inexact fit puts stress on certain bonds of the substrate. This lowers the amount of energy needed to break them.
The enzyme does not form a chemical bond with the substrate. After the reaction, the products are released and the enzyme returns to its normal shape.
Because the enzyme does not form chemical bonds with the substrate, it remains unchanged. As a result, the enzyme molecule can be reused. Only a small amount of enzyme is needed because they can be used repeatedly.
Activation Energy and Enzymes
The amount of activation energy that is required is considerably less when enzyme is present.
Enzymes reduce activation energy.
Conditions that Affect Enzymatic Reactions
Rate of Reaction
Reactions with enzymes are up to 10 billion times faster than those without enzymes. Enzymes typically react with between 1 and 10,000 molecules per second.
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