Enzymes & Catalysis Flashcards
What are Enzymes?
Biological Catalysts that speed up specific enzymatic reactions
They are proteins (not RNAa ribozymes)
-They are present in all organisms
-Every chemical reaction of human cell is regulated by Enzymes
-There can be simple enzymes and multifunctional enzymes
-Their catalytic activity depends on integrity of the native protein folding
What are simple Enzymes?
Enzymes of which are single polypeptide chains
What are allosteric and multifunctional enzymes?
Enzymes of which have other complexes of more subunits
What does the catalytic activity of an enzyme depend on?
The integrity of their native protein folding
What is native protein folding?
What happens if enzymes are denatured or dissociated into subunits?
Catalytic activity is lost
How can an enzyme become denatured? What is it?
What are the properties of Enzymes?
-Specific for the substrates (reactants)
-Catalytic power, fast
-Efficient and not altered after the reaction
-Can be regulated
What is enzyme specificity? and Substrate specificity?
- Ability of the enzymes to specifically recognise the proper substrate (reactant). It is a molecular recognition mechanism. Recognition and specificity is based on structural complementary (three-dimensional fit)
- Substrates bind to a specific region of the enzyme called the active site
- Enzyme-substrate complex (ES) formation is the first step in enzymatic catalysis
What Is the equation for Enzyme-substrate complex?
Substarte Specificity- Lock and key Model-Induced fit
- The active site and substrate are perfectly complementary for each other (like a key fits into its respective lock)
- Induced fit- The substrate is not exactly complementary to the active site. When it binds to the enzyme, a conformational change occurs to allow a better fit between the active site and substrate (like a hand in a glove)
What is the Active Site ?
A 3D pocket/groove, located in a small region of the enzyme
What is the active site composed of?
-Substrate binding site
-Catalytic Site
What is the Substrate binding site?
Amino acids side chains interact with the substrate primarily through hydrogen bonding and other electrostatic interactions. These interactions orientate the substrate within the active site.
What is the Catalytic Site?
Amino acids that catalyse the reaction. The correct folding of the enzymes is required. Substrate-enzyme binding alters the structure of the substrate to promote the formation of the transition state.
What is Catalytic Power?
- Increase the rate of a chemical reaction. Most reactions are at least a million/billion times faster (106 to up to 1017 times) in the presence of an enzyme.
- Orotidine monophosphate (OMP) decarboxylase catalyses reactions in milliseconds that could take 78 million years without an enzyme (1017 times faster)
To start any chemical reaction, what is required?
Energy
The minimum amount of energy required to start a reaction is known as?
ACTIVATION ENERGY
What is Activation Energy?
The energy that must be added to cause molecules to react with each other
-Reactions with a low activation energy will proceed as a faster rate
What happens to reactions with a low activation energy?
The will proceed at a faster rate
What is Enzyme Catalytic Power?-Diagram
Enzyme properties -Efficiency and Reusability
- Enzymes remain unaffected by the reaction which they catalyse
- Not altered or consumed during or after the reaction
- Reusable -they can continue to work if they have more substracts
- They are extremely efficient
- They are active at very low concentrations
Enzyme Properties - Enzymatic Modulation
- Various conditions affect enzyme function (reaction rate)
- Temperature
- Ionic conditions
- pH
- Substrate concentration
- Presence of inhibitors
Enzymes work more efficiently at an…
Optimum temperature of 37 degrees in humans
Higher in some Archea