p.2
International Classification of Enzymes
What type of reaction do transferases catalyze?
Group transfer reactions.
p.2
International Classification of Enzymes
What type of reaction do ligases catalyze?
Formation of C-C, C-S, C-O, and C-N bonds by condensation reactions coupled to cleavage of ATP or similar cofactor.
p.5
Clinical Applications of Enzymes
What are the common samples used for enzyme testing in clinical diagnosis?
Serum/plasma, urine, and cerebrospinal fluid.
p.2
Cofactors and Coenzymes
What is tetrahydrofolate involved in?
One-carbon group transfer reactions.
p.1
Cofactors and Coenzymes
Which coenzyme transfers acetyl groups and what is its dietary precursor in mammals?
Coenzyme A; Pantothenic acid and other compounds.
p.5
Therapeutic Interventions Targeting Enzymes
Which enzyme is targeted to treat bacterial infections by inhibiting bacterial cell wall synthesis?
Glycopeptide transpeptidase.
p.2
Catalytic Mechanism and Specificity
What is the active site of an enzyme?
A pocket on the enzyme where the substrate binds.
p.3
Regulation of Enzyme Activity
What effect does an activator have on an enzyme?
It makes the enzyme active.
p.1
Enzyme Structure and Denaturation
What happens to an enzyme's catalytic activity when it is denatured or dissociated into its subunits?
The catalytic activity is usually lost.
p.4
Regulation of Enzyme Activity
How can enzyme activity be regulated?
By gene regulation and adjustment of synthesis and breakdown of enzyme protein.
p.2
Cofactors and Coenzymes
What is thiamine pyrophosphate involved in?
Aldehyde transfer reactions.
p.1
Cofactors and Coenzymes
What additional chemical components do some enzymes require for activity?
Cofactors (inorganic ions) or coenzymes (complex organic/metalloorganic molecules).
p.2
International Classification of Enzymes
What type of reaction do isomerases catalyze?
Transfer of groups within molecules to yield isomeric forms.
p.2
Enzyme Kinetics and Reaction Rates
What happens to the reaction rate when substrate concentration exceeds a certain level for a fixed enzyme concentration?
The reaction rate may level off.
p.5
Therapeutic Interventions Targeting Enzymes
Which enzyme is targeted to manage high blood pressure?
Angiotensin converting enzyme.
p.3
Regulation of Enzyme Activity
What is an allosteric inhibitor?
A molecule that binds to an enzyme at a site other than the active site, causing a change in its activity.
p.1
Catalytic Mechanism and Specificity
Are enzymes used up or permanently changed during a catalytic process?
No, they are neither used up nor permanently changed.
p.3
Regulation of Enzyme Activity
What effect does an inhibitor have on an enzyme?
It makes the enzyme inactive.
p.1
Enzyme Structure and Denaturation
What factors can cause enzyme denaturation?
pH, temperature, and chemicals.
p.2
International Classification of Enzymes
What type of reaction do hydrolases catalyze?
Hydrolysis reactions (transfer of functional groups to water).
p.3
Regulation of Enzyme Activity
What is an allosteric activator?
A molecule that binds to an enzyme at a site other than the active site, enhancing its activity.
p.1
Definition and Function of Enzymes
Why are enzymes essential for living systems?
They speed up biochemical reactions necessary for life.
p.5
Clinical Applications of Enzymes
What indicates the presence of intracellular enzymes in the blood?
They are synthesized in cells and leak into the blood upon tissue damage.
p.2
International Classification of Enzymes
What type of reaction do oxidoreductases catalyze?
Transfer of electrons (hydride ions or H atoms).
p.1
Catalytic Mechanism and Specificity
How do enzymes speed up the rate of reaction?
By lowering the activation energy.
p.1
Cofactors and Coenzymes
Which coenzyme transfers hydride ions (:H-) and what is its dietary precursor in mammals?
Nicotinamide adenine dinucleotide; Nicotinic acid (niacin).
p.4
Regulation of Enzyme Activity
What is the sequence of events from gene to active enzyme protein?
Gene → mRNA → protein → active enzyme protein → degradation of enzyme.
p.2
International Classification of Enzymes
What type of reaction do lyases catalyze?
Cleavage of C-C, C-O, C-N, or other bonds by elimination, leaving double bonds or rings or addition of groups to double bonds.
p.2
Enzyme Kinetics and Reaction Rates
How does enzyme or substrate concentration affect reaction rate?
Reaction rate increases when enzyme or substrate concentration is increased.
p.3
Regulation of Enzyme Activity
What are the two main types of molecules that can regulate enzyme activity?
Activators and inhibitors.
p.1
Definition and Function of Enzymes
What are enzymes?
Protein molecules that act as natural catalytic agents.
p.1
Cofactors and Coenzymes
Which coenzyme transfers electrons and what is its dietary precursor in mammals?
Flavin adenine dinucleotide; Riboflavin (vitamin B2).
p.2
Cofactors and Coenzymes
What is pyridoxal phosphate?
A coenzyme involved in amino group transfer reactions.
p.2
Catalytic Mechanism and Specificity
What is a substrate in enzymatic reactions?
A molecule that is bound in the active site and acted upon by the enzyme.
