Enzymes Flashcards
Enzymes function by…
lowering the activation energy of reactions
Enzymes biochemically are:
Proteins
(except ribozymes)
Catabolic enzymes
Breakdown reactions, usually generates energy
Anabolic enzymes
Build up reactions, always use energy
How do enzymes exhibit optical specificity?
They act only on the L-isomer of an amino acid or D-isomer of a sugar
How do enzymes catalyze specific reaction or reaction types?
Exhibiting optical specificity
Are enzymes used up in the reaction?
No
Do enzymes alter the equilibrium constants?
No
Do enzymes change the free energy for the reaction?
No
Exergonic reactions
reactions with a –ΔG that spontaneously occur
Endergonic reactions
reactions with a +ΔG that require energy input to occur
Factors affecting the rates of enzyme catalyzed reactions:
Temperature
pH
Enzyme concentration
Substrate concentration
Inhibitors
When temperature increases the rate of reactions…
increase, but at temperatures greater than 102 degrees F, proteins denature
At temperatures below 98 degrees F, reaction rates…
slow down
Example of an enzyme with an optimal pH in acid 1.5-2.0
pepsin in the stomach
Example of an enzyme with a neutral optimal pH 7.3-7.4
carbonic anhydrase in RBC
Example of an enzyme with an optimal pH in base 8.0-9.0
trypsin in small intestines
Increasing both the enzyme and the substrate concentration will…
increase the rate of reaction until a maximum velocity of the reaction is reached
What does the Michaelis-Menten curve describe?
the effects of substrate concentration on activity of many (not all) enzymes
What does the Lineweaver-Burke plot determine?
Experimentally determines Km and Vmax
What is the disadvantage of the Lineweaver-Burke plot?
small experimental error can result in large error in the graphically determined values
What does the Eadie-Hofstee plot determine?
Experimentally determines Km and Vmax
What is the advantage of the Eadie-Hofstee plot?
only one reciprocal
Enzyme inhibition can be:
Competitive, non-competitive, or irreversible or poisons
