Enzymes as Biological Catalysts Flashcards
What is the function of an enzyme?
An enzyme speeds up the rate at which a reaction reaches equilibrium
How do enzymes affect the equilibrium position?
They DO NOT affect the equilibrium position of a reaction
What are enzymes composed of?
Protein
What is the energy of activation?
The energy put into a reaction for that reaction to occur.
How do enzymes affect the energy of activation?
Enzymes reduce the activation energy by providing alternative reaction pathways
What is the transition state of a reaction?
The transition state is the reaction intermediate species which has the greatest free energy
What may the catalytic activity of enzymes require?
Cofactors
What are the two types of cofactors?
Metal ions Organic molecules(coenzymes)
What are tightly bound coenzymes are called?
Prosthetic group
What is an enzyme without cofactor is called?
Apoenzyme
What is an Enzyme with cofactor is called
Haloenzyme
What does symptoms of vitamin deficiencies reflect?
Loss of specific enzyme control
What are the two types of vitamin deficiency?
Dietary Deficiency
Functional Deficiency
What are the properties of the active site?
A cleft or crevice
Contains amino acids essential for catalytic activity
Contains amino acids for highly specific interactions
What are Isozymes?
Isozymes are isoforms of enzymes, they catalyse the same reaction but have different properties and structure (and sequence)
What is Haemoglobin composition during embryonic development ?
Consists of 2 Theta and 2 Epsilon
protein chains
What is Haemoglobin composition during the last trimester of pregnancy?
Consists of two 2 alpha chains and 2 gamma chains
What is Haemoglobin composition after birth?
2 alpha chains and 2 beta chains
What causes denaturation of enzymes?
Temperature
pH
What is the clinical use of Isozymes?
Relative amounts of isozymes in blood are useful for diagnostic purposes
How can enzymes activity be regulated?
Enzymes can be activated or deactivated by phosphorylation
Regulation of enzyme activity by irreversible covalent modification
What are Zymogens?
Inactive precursors of an enzyme
How are Zymogens activated?
Irreversibly transformed into active enzymes by cleavage of a covalent bond
