Biochemistry enzymes flashcards

What is an enzyme?

Enzymes are biological molecules, usually proteins, that act as catalysts to speed up chemical reactions in living organisms. They facilitate reactions by lowering the activation energy required for the reaction to occur.

Differentiate between intracellular and extracellular enzymes.

• Intracellular Enzymes: Operate inside cells.

• Extracellular Enzymes: Work outside cells, often in bodily fluids or secretions.

What is a coenzyme?

Coenzymes are non-protein organic molecules that assist enzymes in catalyzing reactions. They often carry chemical groups between enzymes.

What are apoenzymes?

Apoenzymes are enzymes without their required cofactors. They become fully functional enzymes when combined with cofactors.

Discuss the classification of enzymes.

Enzymes are classified based on the type of reaction they catalyze. Common classes include oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases.

Describe the different factors affecting enzyme actions.

Factors include temperature, pH, substrate concentration, enzyme concentration, and the presence of inhibitors or activators.

Define the Michaelis-Menton equation and discuss the effect of enzyme and substrate concentration.

V=Km​+[S]Vmax​[S]​

• Describes enzyme kinetics.

• V: reaction rate, Vₘₐₓ: maximum rate, [S]: substrate concentration, Kₘ: Michaelis constant.

• As [S] increases, reaction rate initially rises but levels off at Vₘₐₓ.

Describe the actions of inhibiting agents.

Inhibitors decrease enzyme activity. They can be competitive (competing for active sites) or non-competitive (binding elsewhere, changing enzyme shape).

What are irreversible inhibitions?

Irreversible inhibitors permanently inactivate enzymes by forming strong covalent bonds, often modifying the enzyme structure.

What are reversible inhibitions?

Reversible inhibitors bind temporarily to enzymes, and their effects can be overcome. This includes competitive and non-competitive inhibition.

Define competitive inhibition.

Competitive inhibitors resemble the substrate and compete for the active site. They can be overcome by increasing substrate concentration.

Define non-competitive inhibition.

Non-competitive inhibitors bind to an enzyme at a site other than the active site, changing the enzyme's shape and reducing its activity.

What are cofactors?

Cofactors are inorganic ions or coenzymes that help enzymes function. They may assist in catalysis or provide structural support.

What are allosteric enzymes?

Allosteric enzymes have multiple binding sites, and their activity is regulated by molecules binding to these sites, altering the enzyme's shape.

Describe the Template or Lock and Key model of enzyme action.

The model suggests that the enzyme's active site has a specific shape that fits the substrate perfectly, like a key fitting into a lock.

Describe the Induced Fit model of enzyme action.

This model proposes that the enzyme's active site changes its shape slightly to accommodate the substrate, ensuring a snug fit during catalysis.

What are isoenzymes?

Isoenzymes are different forms of an enzyme that catalyze the same reaction but may have different properties, often found in different tissues.

Write a note on the regulation of enzyme activity.

Enzyme activity is regulated by factors like substrate concentration, feedback inhibition, and the presence of activators or inhibitors.

What are coenzymes?

Coenzymes are organic molecules, often derived from vitamins, that assist enzymes by carrying chemical groups between them during catalysis.

Mention the important functions of coenzymes.

Coenzymes assist in various reactions, including carrying electrons (NAD, FAD), transferring chemical groups, and participating in metabolic pathways.

How are enzymes used in clinical diagnosis?

Abnormal levels of certain enzymes in blood or tissues can indicate diseases, making enzyme assays valuable in clinical diagnostics.

What is the relationship between cofactors, coenzymes, cosubstrates, and prosthetic groups?

Cofactors include coenzymes (organic) and inorganic ions. Coenzymes can be cosubstrates, temporary carriers, or prosthetic groups, tightly bound to the enzyme.

What is the function of an enzyme in a chemical reaction?

Enzymes speed up chemical reactions by lowering the activation energy required for the reaction to occur, making the reaction more efficient.

What happens to enzymes when the body temperature rises from 37°C to 42°C?

Enzymes may become denatured, losing their shape and function, as higher temperatures disrupt their delicate structures.

If an enzyme has broken down and is non-functional, what would happen to the chemical reaction normally facilitated by the enzyme? Explain.

The chemical reaction would occur much slower or not at all because the enzyme is necessary for speeding up the reaction.

Why is an enzyme's active site important to the function of the enzyme?

The active site is where the enzyme binds with the substrate, facilitating the catalysis of the reaction. It's crucial for the enzyme's specificity.

Why is the enzyme's regulatory binding site important for controlling the activity of the enzyme?

The regulatory binding site allows molecules to bind and modulate the enzyme's activity, providing a means of controlling and regulating its function.

Why are coenzymes (derived from vitamins) important to the function of some enzymes?

Coenzymes, often derived from vitamins, play crucial roles in enzyme catalysis by carrying and transferring specific chemical groups.

What properties distinguish enzymes from other catalysts?

Enzymes are specific, efficient, and often work under mild conditions, unlike many chemical catalysts. They are highly selective in their actions.