Enzymes Flashcards
How do enzymes affect activation energy?
Enzymes decrease the activation energy needed for a reaction allowing it to proceed faster
What are enzymes?
Are proteins that assist and direct chemical reactions
What is a substrate?
It is the molecule to which an enzyme binds and catalyses a reaction
What is thermal rotation?
The constant vibration, rotation and movement of atoms due to heat energy
What are the four ways enzymes lower activation energy?
- Proximity and orientation changes
- Charge stabilisation
- Bond angle changes
- Covalent bond formation in the enzyme substrate complex
What is the active site of an enzyme?
Is a specifically shaped region of an enzyme where the substrate binds and undergoes a reaction
What is the role of activated carrier molecules in enzyme catalysed reactions?
They store and transfer energy, often binding to enzymes to form high energy intermediates for biosynthesis
What is the transition state in an enzyme catalysed reaction?
Is the high energy intermediate where the substrate is partially broken and partially formed into the product
What factors affect enzyme activity?
- Temperature
- pH
- Substrate concentration
- Inhibitors
What do competitive inhibitors do?
Bind to the active site blocking the substrate
What do non competitive inhibitors do?
Bind on the enzyme (not on the active site) altering its shape and function
What roles do enzymes play in metabolism?
- Regulate metabolic pathways
- Work in teams for complex reactions
- Assist in energy transfer using activated carrier molecules
What is the formula of the Michaelis-Mentel equation?
v = Vmax[S]/(Km+[S])
What does Vmax stand for?
Maximum reaction rate
What does Km stand for?
Substrate concentration at half Vmax
What does low Km mean?
High substrate affinity
What does high Km mean?
Low substrate affinity
What does the Michaelis-Menten tell us?
The rate for a one substrate enzyme catalysed reaction
What is turnover number?
The number of substrate molecules converted to product per enzyme per second
What are the four main enzyme regulation mechanisms?
- Feedback inhibition
- Allosteric regulation
- Reversible inhibition
- Irreversible inhibition
What is feedback inhibition?
Product inhibits early pathway enzyme
What is allosteric regulation?
Effectros change enzyme conformation
What is reversible inhibition?
Competitive or non-competitive inhibitors
What is irreversible inhibition?
Permanent deactivation
What enzyme indicates liver disease?
Alkaline Phosphatase ALP
What enzyme indicated heart attack/muscle damage?
Creatine Kinase CK
How are enzymes targeted in drug design?
Many drugs act as enzyme inhibitors
What is an example of drug inhibiting enzymes?
Drugs which inhibit ACE to reduce high blood pressure
What are the two ways enzymes locate their substrate?
- Through diffusion in solution
- Thermal motion moves molecules randomly
What is a Lineweaver-Burk plot?
A double reciprocal plot of enzyme kinetics that linearise the Michaelis-Menten equation for easier analysis
What are enzyme cofators?
Inorganic metal ions
What are enzyme coenzymes?
Organic molecules
What are prosthetic groups in enzymes?
Permanently attached cofactors or coenzymes
