Catalysis
State what is meant by the term "collision" in enzyme catalysis
The coming together of a substrate molecule and an active site is known as collision
What is the active site of an enzyme?
The active site is the region of the enzyme where substrate molecules bind and undergo chemical reaction.
Explain why not all collisions between enzymes and substrates result in catalysis
The substrate and active site may not be correctly aligned to allow binding take place
What's the description of the induced fit regarding enzyme/substrate binding?
Upon binding to the enzyme, the substrate changes the shape of the enzyme so that it fits perfectly.
Enzymes can be immobilized (e.g embedded in cell membranes). Enzymes can also be free to move, but they tend to move more slowly than substrates, explain why.
The enzymes tend to be larger than the substrate therefore slowing down their movement.
What forms active sites?
Formed from polypeptide foldings
What is the significance of water in enzyme reactions
Most enzyme reactions occur when the substrates are dissolved in water.
What's the name of the model that explains that the active site is flexible and the catalytic group(s) of the enzyme is (are) brought into proper alignment by the substrate?
Induced fit model
What is an endothermic or endergonic reaction?
A reaction where product formation is associated with absorption of energy, usually in the form of heat
Why is the nature of an enzyme's active site not a rigid structure?
In 1958, Daniel Koshland suggested a modification to the lock and key model: since enzymes are rather flexible structures, the active site is continually reshaped by interactions with the substrate as the substrate interacts with the enzyme. As a result, the substrate does not simply bind to a rigid active site; the amino acid side chains which make up the active site are molded into the precise positions that enable the enzyme to perform its catalytic function.
State the fastest enzyme and what it catalyzes
One of the fastest enzymes around is acetylcholinesterase, which is active in the synapses of nerves and muscle fibres.