Enzymes Flashcards
How many cells does the average adult male have?
37.2 trillion
What are enzymes and what do they do?
They are proteins that act as biological catalysts. They speed up the rate of reactions by reducing the activation energy needed for reaction to occur. They are sensitive to temperature and pH.
What do enzymes not do?
- Change or get consumed in a reaction
- Affect the equilibrium of the reaction
- Affect thermodynamic parameters (𝚫G,𝚫H,𝚫S)
- Change spontaneity
What is an exergonic reaction?
Releases energy so products will be lower than the reactants.
What is an endergonic reaction?
Needs energy so the products will be higher than the reactants.
What does an enzyme speed up?
It will speed up both the forward and reverse reaction of the process that it catalyzes. Lowers the activation barrier for reverse reaction too.
What is a substrate?
A substance that an enzyme operates on.
Where do enzyme-substrate interactions occur?
At the active site
What are the two areas that make up the active site?
Binding Site
Catalytic Site
Describe the binding site.
It is larger than the catalytic site and is where the substrate interacts with the enzyme through intermolecular forces (hydrogen bonding, dipole-dipole interactions, and London dispersion factors). It positions the substrate properly relative to the catalytic site. Gives enzyme specificity (can only interact with very specific substrate).
Describe the catalytic site.
It is the specific place where the reaction is catalyzed.
When does the enzyme-substrate complex form?
When the substrate interacts with the active site of an enzyme.
What is the Lock and Key Theory?
It proposes that the active site of an enzyme and the substrate fit together like puzzle pieces with no change in the tertiary or quaternary structure. Turned out to be an oversimplification.
What is the Induced Fit Model?
It proposes that the enzyme and substrate affect each other. The initial stages of binding induce conformational shifts that allow closer binding and more efficient catalysis.
What is a ligand?
Any substance that an enzyme interacts with. Can be a substrate or regulatory molecule.
What are the two regulatory molecules?
Orthosteric Regulation
Allosteric Regulation
What does an orthosteric regulatory molecule do?
It interacts with the enzymes active site.
What does an allosteric regulatory molecule do?
It interacts with other sites on the enzyme that are not the active site.
What is the suffix of all enzymes?
-ase
What does the highest level category of an enzyme tell us?
It describes the chemical mechanism, not the biological function.
What are the 6 highest level categories of enzymes?
- Oxidoreductases
- Transferases
- Hydrolases
- Isomerases
- Lyases
- Ligases
What do oxidoreductases do and what are some examples?
They catalyze oxidation/reduction reactions.
Ex. Alcohol Dehydrogenase, Superoxide Dimutase
What do transferases do and what are some examples?
They transfer functional groups between molecules.
Ex. Aspartate Transaminase, Creatine Kinase, DNA
polymerase
What do hydrolases do and what are some examples?
They catalyze hydrolysis.
Ex. Angiotensin-Converting Enzyme, Pancreatic Lipase,
Lactase
What do isomerases do and what are some examples?
They catalyze isomerization which is the conversion of one isomer to another. Isomers have identical formulas but different structure.
Ex. Ribose-5-Phospate Isomerase
What do lyases do and what are some examples?
They sever bonds but do not use hydrolysis.
Ex. Pyruvate Decarboxylase Aconitase
What do ligases do and what are some examples?
They join molecules together with covalent bonds.
Ex. Aminoacyl tRNA Synthetase, Glutamine Synthetase,
Pyruvate Carboxylase
What does the specific name of an enzyme usually reflect?
Its function
What are the two popular types of enzymes that invole phosphate groups?
Phosphatases
Kinases
What do Phosphatases do?
They remove phosphate groups from a substrate. Dephosphorylation
(Type of Hydrolase)
What do Kinases do?
They add a phosphate group to a substrate. Phosporylation - most likely to occur on Serine, Threonine, and Tyrosine.
(Type of Transferase)
What type of enzyme is trypsin?
It is a protease. Proteases are enzymes that break down proteins. They are a type of hydrolase enzyme.
What is a way that an enzyme can affect the rate of which a biological chemical reaction can occur?
By reducing the physical distance between reactants and manipulated the acid concentration within a catalytic cleft.
What is often necessary for certain reactions to occur?
Altering of the local pH.
What is a trick to use when you’re unfamiliar with an enzyme name?
You can conclude that the enzyme acts on or breaks down whatever comes before the “-ase” suffix.
