Enzymes Flashcards
Define transition state
Highest energy intermediate
What are transition state analogues
Inhibitors of enzymes
What does the enzyme do in terms of the transition state
Lowers the required energy to reach the transition state and positions reactants closer together - this favourable orientation lowers the Ea
3 functions of enzymes
Increase rate of reaction
Decrease activation energy
Facilitate energy conservation and transduction
What does the enzyme undergo in the induced fit model
Conformational change
Define Vmax
Point at which enzymes are saturated and rate cannot be increased
Define V0
Initial rate of reaction
What is the Michaelia-Menton model (2) and what is 1 assumption
- For an enzyme catalysed reaction to proceed an ES complex needs to be formed
- Interactions between E and S are reversible processes
1. There is a constant concentration of ES complexes
Define the 3 rate constants
K1 - Formation of the ES complex
K-1- Reverse process of ES to form E and S
K2 - All other steps in catalytic cycle
Define Km
Michaelia-Menton constant - relative affinity of a substrate for an enzyme
On a graph, what corresponds to the Km
1/2 Vmax
In the Lineweaver-Burk plot what does the Y-intercept represent
1/Vmax
Define turnover number - what is it also called
Maximum number of product molecules produced per unit time per active site - Kcat
What is equal to Kcat/Km
Specificity constant
What is a catalytic strategy
A mechanism adopted by enzymes to facilitate transition state formation
Give 3 advantages of conformational change
- Greater contact area for more interactions
- Facilitating substrate specificity
- Allows exclusion of ‘undesirable’ components
Outline approximation
1 or more substrates brought into the active site in the correct orientation
Substrates are coordinated through non-covalent interactions
What does acid-base catalysis lower and what is the interaction between
Lower energy transition state
Acidic and basic side chains of AA with the substrate
What specific metals are used in metal ion catalysis and what does it facilitate the form of
Transition metals
The transition state
In covalent catalysis where is the covalent bond formed
Between the substrate and the AA side chain
