Exam 2 - Enzyme Activity Flashcards
Is the active site and the substrate binding site the same?
No
What type of inhibition can be reversed by adding substrate?
Competitive Inhibition
What are the 3 types of reversible inhibitors?
- Competitive
- Uncompetitive
- Mixed
- Noncompetitive
Competitive inhibitors compete with the substrate for the [] ?
Substrate binding site
What rate constant is unchanged in competitive inhibition?
k3
What are the 2 conditions for a noncompetitive inhibitor?
- kI and kI’ have to be identical
- The Enzyme-substrate-inhibitor cannot make product
In noncompetitive inhibition why is the Km lowered?
- Psyche
- The Km is unchanged in noncompetitive inhibition
- the Vmax is lowered
In mixed inhibition, KI and Ki’ are [] identical…
NOT identical
What happens to Km and Vmax with the following types of inhibition?
- Competitive
- Mixed
- Noncompetitive
- Uncompetitive
- Vmax is unchanged, Km can change
- Vmax is lowered, Km can go up or down
- Vmax is lowered, Km is unchanged
- Km is lowered, Vmax is lowered
Uncompetitive inhibitors bind to the [] complex only, but does not bind to the [] [] [] ….
ES
Substrate Binding Site
What is the difference between the active site and the substrate binding site?
- Substrate binding site is the site to where the whole substrate binds to
- Acive site are the specific catalytic residues within the substrate binding site.
Allosteric Regulation
- Describes molecules that bind to proteins at some location [] than the substrate binding site - also called the [] site
- Changes [] - positively or negatively
- Targeting []
- Normally small molecules < []
- Other, Allosteric Site
- velocity
- Km
- 3,000 Dal
A compound that alters enzyme activity by binding to sites outside of the substrate binding or active sites…
effector
What is any molecule that is bound to a macromolecule?
Ligand
What is a protomer?
- single subunit in an oligomer
- Usually identical polypeptides
Enzymes that undergo [] regulation tend to be control points in metabolic pathways, or the [] [] []?
- allosteric
- Rate limiting step
Enzymes subjected to allosteric regulation contain an additional binding site called the [] site…
allosteric
Homotrophic Interactions involve what?
Are these interactions negative or positive?
- the binding of 1 ligand to protomers affects binding of ligands on other protomers within the same oligomer
- Usually positive interactions
What type of activity curve to allosteric enzyes have?
altered sigmoidal curve
Heterotrophic interactions involve what?
Are these interactions positive or negative?
- Binding of one ligand affects the binding of a different ligand
- Response can be positive or negative
Protein Kinase A is an example of [] regulation
allosteric
What enzyme degrades cAMP?
cAMP phosphodiesterase
How is a protein kinase activated?
- cAMP interacts with a repressing R group on the catalytic subunit of the protein kinase
- therefore activating the protein kinase.
