Enzymes 2 and Carbohydrates Flashcards
Lineweaver-Burk plot x-intercept
-1/km
Lineweaver-Burk plot y-intercept
1/vmax
Lineweaver-Burk plot slope
km/vmax
Lineweaver-Burk plot x-axis
1/[s]
Lineweaver-Burk plot y-axis
1/vo
competitive inhibition: binding site
- I binds to E only
- I and S bind at same site, compete for binding
- active site, doesn’t affect catalysis
competitive inhibition: km
increases
competitive inhibition: vmax
no change
uncompetitive inhibition: binding site
- I binds to ES only
- I and S bind to distinct sites
- I does not affect substrate binding
- inhibits catalytic function
uncompetitive inhibition: Km
decreases
uncompetitive inhibition: vmax
decreases
mixed inhibition: binding
- I binds E and ES
- I and S bind at distinct sites
- I binds enzyme with or without substrate
- affects catalysis and binding
mixed inhibition: vmax
decreases
mixed inhibition: Km
can increase or decrease
- extreme case becomes noncompetitive and Km is unchanged
irreversible inhibition
- covalent bond between E and I
- transition state analogs (tight binding inhibitors)
- shut down enzyme by resembling transition state
regulatory noncovalent enzymes
allosteric enzyme
- have at least one substrate where Vo vs [s] is sigmoidal
- substrate as activator: homotropic modulator
- multisubunit proteins
regulatory covalent enzymes
reversible, requiring one enzyme for activation and another for inactivation
common mechanism: phosphorylation of ser, thr, tyr, his
carbohydrate structure
- Cn(H2O)n
- produced from CO2 and H2O via photosynthesis in plants
- large size range
carbohydrate function
- energy source, storage
- structural components
d-glyceraldehyde
aldotriose/aldose
3 carbons
dihydroxyacetone
ketomose
3 carbons
d-ribose
5 carbons
all -OH on right side
d-glucose
6 carbons
aldohexose
right: OH, H, OH, OH
d-mannose
C2 epimer of glucose
right: H, H, OH, OH
d-galactose
C4 epimer of glucose
right: OH, H, H, OH
d-fructose
ketomose
chitin
structural component of arthropods
- Beta 1,4 linked polymer of N-acetylglucosamide
starch
amylose, amylopectin
- amylose: unbranched a1-4 polymer of glucose
- amylopectin: 1,4 polymer with 1,6 branches
glycogen
storage unit in animals
a1-4 linked polymer with a1-6 branches
reducing and non-reducing ends: rapid mobilization
cellulose
b1-4 linked polymer of glucose, no branching
one reducing end, one non-reducing end
extensive H-bonding
