Enzyme Classifications and Reactions

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary difference between an apoenzyme and a coenzyme?

Apoenzyme cannot catalyze reactions without a cofactor, but coenzymes can act alone. (correct)

Apoenzyme refers to a complete enzyme, while coenzyme is an additional component.

Apoenzyme is a non-protein part while coenzyme is a protein part.

Apoenzymes are derived from vitamins, whereas coenzymes are made solely of amino acids.

Which statement accurately describes holoenzymes?

They are formed when the apoenzyme combines with a cofactor. (correct)

They consist only of the apoenzyme part.

They require multiple coenzymes to be functional.

They are the inactive form of an enzyme.

In which context do coenzymes primarily function?

As small organic molecules that provide additional reactive groups. (correct)

By permanently altering the structure of the apoenzyme.

By binding directly to metal ions to enhance enzyme activity.

As the main protein structure of enzymes.

Which of the following correctly identifies a role of metal ions as cofactors?

Metal ions may be directly incorporated into the structure of the enzyme or to a coenzyme. Signup and view all the answers

What characterizes coenzymes derived from vitamins?

They contribute additional functional groups necessary for catalytic activity. Signup and view all the answers

Which of the following is involved in the hydrolysis of proteins?

Proteases Signup and view all the answers

What type of reaction do decarboxylases catalyze?

Removal of carboxyl groups Signup and view all the answers

What is the role of cofactors in enzymatic reactions?

To assist in facilitating a chemical reaction Signup and view all the answers

Which enzyme class is primarily responsible for the addition or removal of atoms to or from a double bond?

Lyases Signup and view all the answers

What does the term 'apoenzyme' refer to in enzymology?

The protein-only part of an enzyme Signup and view all the answers

What is the primary purpose of releasing enzymes in their inactive form, as zymogens?

To prevent them from damaging the tissues that produce them Signup and view all the answers

Which enzyme is responsible for the addition of a phosphate group to an enzyme during the phosphorylation process?

Kinase Signup and view all the answers

What happens to glycogen synthase when it undergoes phosphorylation?

It gets deactivated from its glycogen synthesis role Signup and view all the answers

Why are B vitamins necessary for the function of some enzymes?

They provide temporary carriers of atoms or functional groups Signup and view all the answers

What mechanism can alter enzyme activity through covalent modification?

Phosphorylation and dephosphorylation Signup and view all the answers

How do coenzymes differ from apoenzymes in their interaction with enzymes?

Coenzymes are released after the enzymatic reaction is complete Signup and view all the answers

What is the role of coenzymes in metabolic reactions?

To provide chemical reactivity that is absent in the apoenzyme Signup and view all the answers

During which process is a phosphate group removed from an enzyme?

Dephosphorylation Signup and view all the answers

What is the main action of ACE inhibitors in the body?

Inhibit Angiotensin-Converting Enzyme Signup and view all the answers

What role do sulfa drugs play in antibiotic treatment?

They inhibit the enzyme that converts PABA to Folic acid Signup and view all the answers

Which enzyme is measured indirectly to indicate kidney function?

Urease Signup and view all the answers

At what temperature do human enzymes typically exhibit maximum activity?

37°C Signup and view all the answers

How does increased temperature affect enzyme kinetics?

Increases reaction rate until optimal temperature is exceeded Signup and view all the answers

What is the consequence of exceeding the optimum temperature for an enzyme?

Denaturation of the enzyme Signup and view all the answers

Which enzyme is specifically inhibited by penicillin?

Transpeptidase Signup and view all the answers

What happens to lactate dehydrogenase (LDH) levels in the blood during a myocardial infarction?

Levels markedly increase Signup and view all the answers

What does an increase in lactate dehydrogenase (LDH) levels indicate?

Myocardial infarction (MI) Signup and view all the answers

Which enzyme is primarily involved in dissolving blood clots during treatment of myocardial infarction?

Tissue plasminogen activator (TPA) Signup and view all the answers

How does urease assist in measuring blood urea levels?

By converting urea into a quantifiable compound Signup and view all the answers

What is the primary function of aldolase?

To convert glucose into energy Signup and view all the answers

Which isoenzyme of lactate dehydrogenase (LDH) is primarily associated with heart muscle?

LDH1 Signup and view all the answers

What is a primary indicator of kidney malfunction in blood tests?

Increased urea concentrations Signup and view all the answers

What role do isoenzymes play in medical diagnosis?

They provide information about specific tissue damage. Signup and view all the answers

What is the significance of measuring Blood Urea Nitrogen (BUN)?

It assesses kidney function. Signup and view all the answers

Study Notes

Enzyme Classification and Function

Hexokinase catalyzes the phosphorylation of glucose, producing glucose-6-phosphate using ATP.
Hydrolytic enzymes include lipases (break down lipids) and proteases (break down proteins).
Lyases catalyze addition or removal of atoms from double bonds; decarboxylases remove carboxyl groups.
Isomerases facilitate isomerization reactions, converting aldoses to ketoses; mutases transfer functional groups within substrates.
Ligases synthesize by joining two molecules, forming a new chemical bond, usually coupled with ATP hydrolysis.

Enzyme Structure

Simple enzymes consist solely of protein.
Conjugated enzymes are composed of an apoenzyme (protein part) and a cofactor (non-protein part) required for catalytic activity.
Holoenzyme is the functional combination of an apoenzyme and cofactor.

Enzyme Modifications

Covalent modification, often involving phosphorylation and dephosphorylation, regulates enzyme activity.
Kinases add phosphate groups (phosphorylation), while phosphatases remove them (dephosphorylation).
Example: Glycogen synthase is deactivated by phosphorylation; glycogen phosphorylase is activated by phosphorylation.

Importance of Coenzymes

Coenzymes, derived from vitamins, assist enzymes by providing additional reactive functional groups.
B vitamins often act as coenzymes, vital for metabolic reactions and energy release from food.
Coenzymes do not permanently bind and can be reused across different enzymes.

Enzyme Activity Regulation

Factors affecting enzyme activity include temperature, pH, substrate concentration, and enzyme concentration.
Increased temperature generally raises kinetic energy, enhancing reaction rates to an optimum level, beyond which enzymes may denature.

Medical Applications of Enzymes

Enzymes serve in diagnosis and treatment; elevated levels of lactate dehydrogenase (LDH) indicate myocardial infarction.
Tissue plasminogen activator (TPA) activates plasminogen to dissolve blood clots, useful in heart attack treatment.
Urease is utilized to convert urea to ammonia, allowing for blood urea nitrogen (BUN) measurement to assess kidney function.

Aldolase and Isoenzymes

Aldolase converts glucose into energy and its levels rise with muscle damage; tests for aldolase help diagnose skeletal muscle conditions.
Isoenzymes catalyze the same reaction but vary across tissues, e.g., LDH isoenzymes; LDH1 is more prevalent in heart muscle, while LDH5 is found in skeletal muscle and liver.

Drug Inhibition of Enzymes

ACE inhibitors lower blood pressure by inhibiting angiotensin-converting enzyme.
Sulfa drugs act as competitive inhibitors of bacterial enzymes, disrupting folic acid synthesis and inhibiting bacterial growth.
Penicillin inhibits transpeptidase, weakening bacterial cell walls and leading to cell lysis.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the major classes of enzymes, their functions, and the biochemical reactions they catalyze. This quiz will cover topics such as hexokinase, hydrolases, lipases, and proteases. Test your knowledge of enzymatic processes and biochemical pathways.