Enzymes Flashcards
Enzymes are proteins which act as…
Catalysts
Many drugs (and poisons) are…
Enzyme inhibitors 🛑
Penicillin binds to and inhibits the enzymes that make bacterial…
Cell Wall 🏰
Enzymes are ( non-specific / somewhat specific / highly specific )
Highly specific
Enzymes catalyse the making and breaking of ? in the cell
Covalent bonds
Enzymes allow reactions to take place more quickly and often at lower temperature and milder…
pH 👨🏻🔬
The regulation of biochemical reaction pathways is often controlled by…
Enzymes
The equation for Gibbs Free Energy is…
𝚫G = -RT(ln Keq)
Enzymes (increase / reduce / do not change ) activation energy
Reduce ⬇️
By binding the reactant an enzyme changes the reaction environment, which lowers activation energy by providing an alternative…
Transition state
Enzyme (do / do not / sometimes) affect Keq (equilibrium constant)
Do not 🙅♀️
Enzymes work on 3 principles
- Proximity (bringing reactants closer together)
- Orientation (arranging reactants favourably)
- Strain / Distortion (applied to bonds)
Acid/base catalysis allows reactions to overcome low concentrations of…
H+/OH- (protons/ hydroxide ions)
In covalent catalysis, a temporary…
Covalent bond is formed between enzyme and substrate
The two models of the enzyme-substrate (ES) complex are…
- Lock and key 🔐
2. Induced fit
The four levels of enzyme specificity are…
- Absolute
- Bond specific
- Group specific
- Stereospecific (differentiates stereoisomers)
There are 6 types of reactions which may involve enzymes…
- Redox
- T Transferases
- H Hydrolases
- L Lyases
- I Isomerases
- L Ligases (synthases)
The turnover of an enzyme, or the number substrate molecules that can be converted to product by 1 enzyme in 1 second is quantified as… ⏳
Kcat
Enzyme activity can be measured using…
Spectrophotometry
To measure enzyme activity, we should measure the initial rates of reaction, as…
This is the only time when the substrate concentration is exactly known
Equation for the rate (V) at a specified substrate concentration ( [s] )…
V = Vmax [s] / Km + [s] 🏎
Km is the concentration of substrate needed to achieve…
1/2 Vmax 📈
Km indicates the affinity of the enzyme for a substrate, i.e.
Stability of the enzyme-substrate complex (high stability, low Km & v.v.)
Km is known as the Michaelis Constant and is calculated by fitting data using a non-linear least squares fitting programme. Why can’t Vmax be measured directly?
Because it occurs when the substrate concentration reaches infinity ( [s] = ∞ )
