enzymes Flashcards
what are enzymes?
tertiary structure proteins
what does it mean that enzymes are tertiary structure proteins?
they are a very specific 3d shape
what do enzymes include?
an active site
what bonds are there in enzymes?
-peptide bonds
-hydrogen bonds
-ionic bonds
-disulfide bonds
what happens in the lock and key theory?
-a successful collision has the subsrate fit exactly into the active site of the enzyme firing an enzyme/substrate complex
-the reaction occurs
-the products are released
-the enzyme remains unchanged at the end of the reaction
what is the induced fit theory?
an alternative theory of enzyme action
what happens in the induced fit theory?
-the active site and substrate are not fully complementary in shape
-reactive groups in these areas align
-the substrate forces its way into the active site
-both areas change structure slightly
-the bonds in the substrate weakens
-the reaction occurs at a lower activation energy
what are enzymes?
catalysts
what does the catalyst do?
they lower the activation energy of reactions but remain unchanged in the reaction
what factors affect enzyme reaction?
-temperature
-pH
-substrate concentration
-enzyme concentration
how does temperature affect enzymes?
-At low temperatures, there is low kinetic energy, leading to fewer successful collisions between enzymes and substrates.
-As temperature increases, kinetic energy rises, forming more enzyme-substrate complexes until the optimum temperature is reached.
-Beyond the optimum temperature, excessive vibrations weaken the bonds in the enzyme’s tertiary structure, altering the active site.
-This prevents substrate binding, leading to enzyme denaturation and loss of function.
how does pH affect enzymes?
-Enzymes have an optimum pH, where they function most efficiently
-Small pH changes cause reversible structural changes, slightly reducing enzyme efficiency.
-Large pH changes disrupt ionic and hydrogen bonds, permanently altering the active site.
-This prevents enzyme-substrate complex formation, leading to enzyme denaturation.
how does substrate concentration affect enzymes?
-Enzyme reactions depend on successful collisions between enzymes and substrates.
-Increasing substrate concentration initially increases the rate of reaction as more collisions occur.
-At low substrate concentrations, the substrate is the limiting factor.
-Once all enzyme active sites are occupied, adding more substrate does not increase the rate—the reaction plateaus.
-At this point, enzyme concentration becomes the limiting factor.
how does enzyme concentration affect enzymes?
assuming an excess of substrate any increase in enzyme concentration increases the rate of reaction as more active sites are available for reactions
what are the two inhibitors?
-competitive
-non-competitive
what are competitive inhibitors?
inhibitors that are in similar shape to the substrate so competes with the enzyme for active sites
what are non-competitive inhibitors?
inhibitor that are complementary to another site on the enzyme and distorts active site shape so substrate cannot bind to the active site
what effect does competitive inhibitors have on substrate concentration?
the effect of the inhibitors will decrease if there is an increase in substrate concentration as the substrate will collide more often than the inhibitor with the active site of the enzyme
what effect does non-competitive have on substrate concentration?
an increase in substrate concentration has no effect on a non-competitive inhibitor
what are intracellular enzymes?
-these work inside cells
-extracellular enzymes are secreted from cells for use outside of the cell
what is metabolism?
anabolic reactions and catabolic reactions are catalysed by enzymes
what are anabolic reactions?
building up of molecules
what are catabolic reactions?
breaking down of molecules
