Protein/Enzyme Function Flashcards
Oxireductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
Catalyze redox rxns
Catalyze trasfer of C, N, P containing groups
Cleave of bonds by addition of H20
Cleave CC, CS, CN
Catelyze racemization of optical geo isomers
Catalyze formation of bonds between C and O, S, N coupled to hydrolysis of high energy phosphates
Synthase vs syntheses
phosphatase vs phosphorylase
oxidase vs oxygenase
req atp vs no req atp
uses water to remove P, uses P to break bond and make phosphorylated product
O2 acceptor but no oxygen in product, one or both Oxygen atoms incorporated
Vmax
Velocity when all enzyme is saturated
Hyperbolic vs sigmoidal curve
Allosteric
-due to cooperative subject binding
Michaelis Menten Eq 92)
rate of reaction and [E], [S]
[S]>Km
v=Vmax[S]/Km+[S]
v=kcat[E][S]/Km+[S]
directly proportional
v=[S]
v=Vmax
Km
Michaels constant
depends on enzyme and sub
-refelcts affinity
Km=Vmax/2
no vary with [E]
Low Km-high affinity-low concentration needed to half saturate enzyme
Lineweaver burk axis
intercepts
1/Vo x 1/[S]
x intercept=-1/km
y intercept=1/Vmax
DRAW
Competitive inhib
Vmax
Km
Lineweaver Burk
bind reverisble to same site as substrate
Reverse effect by increasing [S]
high[S]=Vmax as in absence of inhib
increases apparerent Km
More substrate needed to hit 1/2Vmax
vmax unchaged
Km increased in presence of inhib, -1/Km moves closer to 0
DRAW
Noncompetitive Inhib
Vmax
Km
Lineweaver burk
binds to either ES complex or enzyme
Decrease Vmax-cannot overcome noncomp inhab by increasing substrate
Same Km-does not interfere with binding affinity
Vmax is notably decreased and Km is unchanged
draw this bitch
Holoenzymes
active enzyme with non protein component
apoenzyme
inactive enzyme
cofactor
metal factor for enzyme
coenzyme
small organic molecule
prosthetic group vs cosubstrate
bind to enzyme to make work
transiently bind to enzyme to make work
isoenzymes
same chemical run but different primary structure/aa seq
different in different tissues
Different temp/ph/kcat/Km properties
Can use to diagnose
Keq
[P]/[S]
amt of substrate and product present @ eq
REDOX enzymes
typically regenerated by other enzymes (NADH, FADH)
Enzyme rate limiting step and how to slow even more
ejection of product
slowed by tighter binding
Why doesn’t lock and key work
reaction site can be same-but territory strutreu must allow/help
Induced fit
Enzyme creates CONFORMATIONAL change in enzyme
flexible active site
Reaction rate and AE relationship
inverse
Transition state stab
ENZYME BINDS BETTER TO TS then substrate-but still well to substrate
Enzymes change
Velocty
NOT-Keq or free energy,
Cat starts (5)
proximity, tss, covalent cat/nuc cat, acid base cat, metal ion cat
Chymotripsin
3 types of cat+where
cat triad
cleaving?
activation cleaving
Has nuc/covalent cat
- serine O- bonds with amide covalently
- serine is potent nucleophile when deprotonated
general acid/base cat
- HIs accepts proton from Ser
- his becomes potent Nucleophile
- forms key intermediate tetrahedral
- HisH then donates H to help acyl enzyme formation
- creates acyl enzyme (slow step)
TSS by oxyanion hole
- READY FOR - GROUP
- Made of Ser and Gly
- stabilize tetrahedral
serine, histidine, aspartate
cleave after aromatic AA’s
peptide bond
how to make endergonic rxn go
Couple with exergonic
Energy in ATP/ADP
Cov bond vs noncov
3.5 and 2.5 kj/mol
50 to .5
Does delta G say anything about rate?
NO
can have long pathway-end is exergonic so -G is low, but long
Velocity
change in concentration of S or P over time (slope of conc vs time graph)
Kcat=
relation to enzyme, substrate, Km, pH and temp
Vmax/[E]
rate at which substrate on enzyme becomes free product
-turnover time for conversion
changes for pH and temp
similar to Km
constant for enzyme and substrate
slide 69 and 3 amino acid at ph problems
do these
phosphorylation of enzymes
mostly on Ser, some on Thr, and 1% of tyr-these have neg charges
can activate or deactiate enzyme
Proteolysis
irreversible means of activating enzymes
ex. hydrolyze peptide to activate chymotrypsin
Inhibition pathways (4)
irreversible (covlanent bond), reversible, comp (looks similar)/noncomp
Transition state analogs
amazing inhibits
stable molecules that resemble geo/electro features of highly unstable TS
binds tighter to enzyme TS
allosteric enzymes
oligomeric
active and all site binds what?
have actie and allosteric site
all oligomeric
active site binds s
allo site binds effector/regulator
molecules do not resemble substrates
K.05 meaning
when half substrate velocty????
R and T
how modulate eq
R=relaxed-active
-binds S better and higher cat activity
T=taught-inactive
-binds S weakly and lower cat activity
effectors/regulators
Allo activator binding vs allo inhibitor binding
act-stabilizes R-increases S binding and increased activity
Inact-stabilizes T-decrease S bindng and decreased activity
K type inhib
increase k.05 not affect Vmax decrease apparent affinity for S low[S]-enzyme activity lower than normal high[S]=enzyme activity is normal
makes substrate binding weaker
v-type inhib
V-type inhibitor will decrease Vmax V-type inhibitor will not affect K0.5
Will not affect the affinity of S for the E At all [S], activity of E is lower
k-type activator
K-type activator will decreases K0.5 K-type activator will not affect Vmax
Will increase the affinity of the S for the E At low [S], activity of E is higher
At higher [S], activity of E is normal.
v-type activator
V-type activator will increase Vmax V-type activator will not affect K0.5
Will not affect the affinity of the S for the E At all [S], activity of E is higher
