Unit 5 - Redone Flashcards
Isoenzymes
Different forms of enzymes that catalyze the same reaction
How enzymes work
Increase rate of biochemical reactions that are already possible
What is acted upon by an enzyme?
Substrate
An enzyme increases the rate of a reaction how?
Lowering the activation energy needed
T/F: the ratio of the final equilibrium that already COULD occur between substrate and product are unchanged by an enzyme
True
Where are enzymes synthesized
Intracellularly
Where is ALKP produced?
BLIP
Bones, Liver, Intestines, Placenta
Do enzymes live/exist forever?
No, they eventually get degraded and metabolized out
Where do substrates bind?
To the active or catalytic site of an enzyme
What dictates which direction an enzymes occurs at?
Law of Mass Action
High to low concentration
What does an enzyme need to function?
Cofactor
Where do cofactors bind?
Allosteric site
Apoenzyme
Enzyme w/o cofactor
Holoenzyme
Enzyme w/ cofactor
Prosthetic group
Cofactor bound so tightly to the enzyme it looks like its part of the enzyme
Absolute specificity
Enzyme only reacts with one substrate
Group specificity
Enzyme only reactions with substrates that contain a specific group on the molecule
Stereoisomeric specificity
Enzymes only work with specific isomers or 3D configurations
Normally, what is supplied in excess to measure an enzymes activity?
Substrate
First order kinetics
Low substrate concentration relative to excess enzyme concentration
Product formation depends on substrate concentration
Zero order kinetics
Substrate in excess
Enzyme able to reach Vmax
Enzyme can’t work any faster
Mixed order kinetics
Center of the graph that is mixed and unpredictable
What does Km represent
Substrate concentration where enzyme catalyzes half as fast as it can (1/2 Vmax)
How is the Km found?
Testing by Changing substrate concentration with a constant amount of enzyme present
What should be in excess during enzyme measurement
Substrate
What should be in excess during substrate measurement
Enzyme
What does it mean if substrate exhaustion during enzyme measurement?
Loss of linearity in substrate measurement,
Dilute and retest
High Km means
Low affinity
Low Km means
High affinity
The substrate with the highest Km will require…
The highest amount of substrate to achieve Vmax
Lag Period
Little product formed
Linear Period
Equilibrium reached
Vmax
Nonlinear Period
Substrate exhaustion
Standard International Unit of enzyme activity (IU/L)
Quantity of enzyme that will catalyze the reaction of 1 micromole of substrate/min
First order kinetics linearity
0 to the Km
Zero order kinetics linearity
Up to the Vmax
Lineweaver-Burk plot X and Y axis
X - 1/Km
Y - 1/Vmax
X intercept moves which way when Km is lower?
Left, enzyme activity is better
X intercept moves which way when Km is higher?
Right, enzyme activity is worse
Y intercept moves which way when the reaction slows down?
Up
Y intercept moves which way when the reaction speeds up?
Down
Km and Vmax with competitive inhibitions
Km increases
Vmax unaffected
How does competitive inhibition work
Inhibitor binds to active site
How does non competitive inhibition work
Inhibitor binds to allosteric site
Non-competitive Inhibition Km and Vmax
Km unaffected
Vmax lower
Uncompetitive Inhibition Vmax and Km
Km and Vmax both affected
How does uncompetitive Inhibition work
Inhibitor binds Enzyme+Substrate complex
