Topic 3: Enzyme Flashcards
Activation Energy
The energy that must be provided to make a reaction take place; enzymes reduce the activation energy required for a substrate to change into a product.
Active Site
An area on an enzyme molecule where the substrate can bind.
Allosteric
Other site.
ATPase
.
Buffer Solution
An aqueous solution consisting a mixture of weak acid and its conjugate base, or vice versa, which has a fixed pH value.
Cofactor
Other factor
Competitive Inhibition
When a substance reduces the rate of activity of an enzyme by competing with the substrate molecules for the enzyme’s active site; increasing the concentration of the substrate reduces the degree of inhibition.
Denaturation
Above a certain temperature, the structure of enzyme molecule vibrate so energetically that some of the bonds holding the enzyme molecule in its precise shape begin to break and the enzyme molecules begin to lose its shape and activity.
End-Product Inhibition
End products accumulate within the cell and stop the reaction when the sufficient product is made
Enzyme
a protein produced by a living organism that act as a biological catalyst in a specific reaction by reducing activation energy but remains unchanged at the end of the reaction.
Enzyme-Substrate Complex
The combined structure in which the substrate is held in place by temporary bonds which form between the substrate and some of the E groups of the enzyme’s amino acids
Extracellular
Enzymes that are secreted by cells and catalyse reaction outside the cell.
Feedback Mechanism
.
Immobilised Enzyme
Enzymes that have been fixed to a surface or within a bead of agar gel
Induced Fit Hypothesis
The substrate is complementary shape to the active site of the enzyme but the substrate is not an exact fit.
Enzyme or sometimes the substrate can change its shape in order to ensure a perfect fit for catalysis to occur.
Inhibitor
A substance that decrease or stop enzyme activity.
Intracellular
Enzymes that operate within cells
Irreversible Inhibitor
Inhibitors that damage the enzyme irreversibly leaving them permanently damaged.
Lactose
Disaccharides that are found in milk
Lock and Key Hypothesis
Enzyme has a particular fixed shape into which the substrate fits perfectly analogous to a key fitting into a lock.
Lysozyme
An enzyme that damage the cell wall (made of polysaccharide chains) of bacterias by catalyse the hydrolysis
Metabolic Reaction
All the reactions that take place in a living organism
Michaelis-Menten constant, km
The substrate concentration at which an enzyme work at half it maximum rate (1/2 Vmax), used as a measure of the efficiency of an enzyme; the lower value of km, the more efficient the enzyme.
Non-Competitive Inhibitor
A substance reduce the rate of activity of an enzyme by binding to another site of the enzyme rather than the active site.
Optimum
The best possible result; the ideal result
The temperature at which an enzyme catalyse the reaction at the maximum rate
pH
A measure of concentration of hydrogen ion in the solution
Reversible Inhibitor
Enzyme inhibitors that do not damage the enzyme permanently and do not break the disulphide bond.
Saturation
All the active site are bound to substrate to form an enzyme-substrate complex
Substrate
Molecules that react in the enzyme catalysis reaction
Theoretical Maximum Rate (Velocity), Vmax
The theoretical maximum rate of an enzyme controlled reaction, obtained when all of the active sites are occupied.
Turnover Rate of Enzyme
The speed at which an enzyme can convert substrate into a product. A typical enzyme can convert around one thousand substrate molecules into product per second.
