3.0 Enzymes and Energetics Flashcards
What’s an enzyme and its specificity?Reference equilibrium? What do they do?
A protein that acts as a catalyst (speeds up by 10(6) – specificity is due to protein confirmation
Do not alter equilibrium but only speed both forward and backwards reaction
Lower Ea
What happens when we lack an enzyme? Give example
Glucose-6-phosphatese is an enzyme that removes the terminal phosphate group allowing glucose to be released from glycogen. Without it it causes glycogen storage disorder leading to large tummy and glucose stuck in liver
What is entropy?
A measure of the degree of disorder – reaction only proceed in the direction with the largest entropy
How are biological organism in good order?
They use energy from the surroundings to maintain order within the cell, however they make the surroundings more disordered - hence no law of thermodynamics is broken.
What are the two laws of thermodynamics?
1st - Energy cannot be created nor destroyed only transferred from one store to another
2nd - Entropy in an isolated system (universe) can only go up to a more disordered state
ATP?
Adenise triphosphate
Makes energetically unfavoured reactions favourable
What is Gibbs free energy? What’s delta G? Exo?
Amount of energy in a molecule that can perform good work.
Delta G measured the amount of disorder arisen from a reaction. Its products minus reactants
Delta G = -ve = exo
What’s a transition state?
When the substrates conformation is geometrically and electronically rearranged so that the reaction can proceed.
Lysozyme enzyme? Where? How? Optimum pH and temperature?
Found in tears and mucus – breaks down sugars (NAG and NAM) commonly found in bacterial cell wall (they’re important) – breaking them down causes the bacteria to die. – pH: 5 (because glu-35 is protenated and asp-52 is ionised), temperature: 57
How do enzymes work? Residues
They allow a substrate to bind to their active site which puts pressure on the bonds that need to be broken and also makes the substrate resemble the transition state.
Residues of enzyme cause change in electron arrangement often in the form RED/OX
What are the 6 metabolic reactions:
REDOX - e transferre
Hydrolytic - cleavage by using water
isomerisation - rearranging atoms to form isomers
group transfer - transferring functional group
Adding/removing functional groups - add to double bond or remove to make double bond
legation (requires ATP) - forming covalent bond – ligation refers to joining DNA strands
Active site models?
Lock and key – substrate matches the active site
Induced fit – substrate induces conformational change in protein structure thus shaping the active site – after the enzyme returns to its original state. CORRECT!
Lysozyme residues explanations?
Glutamate -35 and aspartate-52 are the key residues.
Glu-35 gives a proton to NAG causing it to hydrolyse off NAM, then H20 re-protenates glucose-35 and gives a OH to NAM. All while asp-52 maintains charge stability.
NAD+?
Nicotinamide adenine dinucleotide
Helps enzymes by acting as a hydride acceptor (two e and one proton)
Its a co-factor for dehydrogenation reactions
