Enzyme structure - Properties of enzymes

Summary

Enzymes are specialized proteins that accelerate reactions, consisting of a protein part (apoenzyme) and a non-protein part (cofactor). The cofactor, which may be a metal ion or coenzyme, influences the enzyme's shape and its ability to catalyze reactions. Enzymes are highly specific, efficient, and can process thousands of substrate molecules per second. They can also be regulated by genes or substances in the cell, with cofactors playing a key role. Digestive enzymes, for example, remain inactive until they encounter specific conditions like hydrogen ions, which activate them by altering their structure.

Takeaways

• 😀 Enzymes are special proteins that catalyze reactions.
• 😀 Enzymes consist of two parts: the protein part (apoenzyme) and the non-protein part (cofactor).
• 😀 Cofactors can be metal ions or organic molecules called coenzymes, with vitamins being raw materials for coenzymes.
• 😀 The cofactor affects the enzyme's final shape, influencing its ability to catalyze reactions.
• 😀 Enzymes act upon substrates at their active sites, which are specific to the substrate's shape.
• 😀 Enzymes are highly specific and usually catalyze only one or a few reactions.
• 😀 Enzymes are extremely efficient, speeding up reactions by more than 10 million times.
• 😀 A single enzyme can process over 10,000 substrate molecules per second.
• 😀 Enzyme activity can be controlled by genetic factors and the concentration of proteins.
• 😀 Enzymes can be inhibited or enhanced by substances within the cell, and cofactors play a role in this.
• 😀 Many enzymes exist in inactive forms and are activated by their chemical surroundings, such as digestive enzymes in the stomach.

Q & A

What are enzymes and what role do they play in chemical reactions?

Enzymes are special types of proteins that catalyze chemical reactions, speeding them up by lowering the activation energy needed for the reaction to occur.

What are the two parts of an enzyme and what is their function?

An enzyme consists of two parts: the protein part called the apoenzyme, and a non-protein part called the cofactor. The cofactor can be a metal ion or an organic molecule called a coenzyme, and it helps the enzyme function properly.

How do vitamins relate to coenzymes?

Vitamins serve as raw materials for many coenzymes, which are essential for the functioning of enzymes.

How does a cofactor affect an enzyme's activity?

A cofactor often affects the final shape of the enzyme, which in turn influences its ability to catalyze reactions efficiently.

What is a substrate in relation to an enzyme?

A substrate is the molecule upon which an enzyme acts. The enzyme's active site interacts with the substrate to facilitate the reaction.

What is the active site of an enzyme?

The active site is the region of the enzyme that directly interacts with the substrate and is where the chemical reaction takes place.

What are the three important properties of enzymes?

The three important properties of enzymes are: specificity (enzymes catalyze only specific reactions), efficiency (enzymes catalyze reactions at a much faster rate than without them), and controllability (enzymes can be regulated by various factors such as gene expression or external substances).

How specific are enzymes in their function?

Enzymes are highly specific, meaning they typically catalyze only one or two types of reactions. This specificity comes from the close fit between the enzyme's active site and its substrate.

How efficient are enzymes in catalyzing reactions?

Enzymes are incredibly efficient, catalyzing reactions at rates more than 10 million times faster than the reactions would occur without them. A single enzyme molecule can process over 10,000 substrate molecules per second.

How can enzyme activity be controlled?

Enzyme activity can be controlled through genetic regulation, which affects the concentration and synthesis rate of enzymes. Additionally, enzymes can be inhibited or enhanced by other substances, such as cofactors or inhibitors, within the cell.

What happens when an enzyme is inhibited?

When an enzyme is inhibited, the active site may become inaccessible, preventing the enzyme from interacting with its substrate and catalyzing the reaction. This inhibition can be due to the presence of an inhibitor.

How are digestive enzymes activated?

Digestive enzymes are often produced in an inactive form and are activated when they come into contact with hydrogen ions. These ions break certain bonds in the enzyme, exposing the active site and allowing it to function.