Enzymes Flashcards
Enzymes - what are they, what is their purpose?
enzymes are protein catalysts
speed up the rate of chemical reactions without being consumed
Substrate
a substrate is what is being decomposed by the enzymes (food/nutrient)
Active site
the active site is the region on the enzyme where the substrate is being decomposed
Enzyme substrate complex
when enzyme and substrate are joined, they form an enzyme-substrate complex
Describe the induced-fit model
when functional groups in the substrate interact with functional groups within the enzyme to help the substrate
What is activation energy (Ea)? How does it change when enzymes are involved?
Activation energy (Ea) is the energy needed for a chemical reaction to occur, and enzymes lower this energy, making reactions happen more easily and quickly.
Define cofactor
are non-proteins (often metals like Fe, Cu, Zn & Mn) that can bind to an enzyme and are essential for the catalytic activity of the enzyme that they bind to
How does the concentration of an enzyme affect the rate of a catalysis reaction?
Increasing enzyme concentration usually speeds up the reaction rate because there are more active sites for the substrate, but this only works until the substrate runs out.
How does the concentration of a substrate affect the rate of a catalysis reaction?
As substrate concentration increases, the rate of a catalytic reaction increases until the enzyme is saturated, after which adding more substrate won’t speed up the reaction.
How does the pH and temperature affect the rate of a catalysis reaction?
The rate of a catalytic reaction is affected by pH and temperature, as each enzyme works best within a specific pH range and temperature; too much change can slow down the reaction or inactivate the enzyme.
A competitive inhibitor
- are similar in structure to the substrate
- are able to bind with the active site
- block the normal substrate from binding
A noncompetitive inhibitor
- do not compete with substrate for the active site
- attach to a different site on the enzyme which changes its shape causing the substrate to not bind
properly
Allosteric site
The allosteric site is a spot on an enzyme where other molecules can bind, changing the enzyme’s shape and affecting its activity, separate from where substrates attach.
Describe feedback inhibition
Feedback inhibition is when a product slows down its own production; if there’s too much, it stops the process, and if there’s too little, the process speeds up, keeping the amount just right.
Coenzymes
- very similar to cofactors
- come from water-soluble vitamins
- responsible for shuttling molecules from one enzyme to another
- e.g.,. NAD is an electron carrier in many pathways
