Enzymes - Davies Flashcards
Cofactors
small inorganic attachments to enzymes
Coenzymes
Organic Molecules that attach to enzymes.
Metalloprotease
Require metal ion to cleave proteins (uses Zn)
Kinase
Uses Mg to work and is calcium concentration depended. it wil lphosphorylate
Oxidoreductase
oxidate and reduction reaction
Transferase
transfer functional group
Hydrolase
catalyze bond cleavage with water
lyases
c-c bond cleavage
isomerase
move a group or a double bond
ligases
catalyze joining of a c-c bond
apoenzyme
enzyme without cofactor
haloenzyme
functional enzyme with cofactor
Trypsin
Serine protease, cleaves at arginine and lysine (basic)
Chymotrypsin (just what it cleaves)
serine protease cleaves at Phe, met, trp
Thrombin
serine protease cleaving at arg-gly bonds
ΔE*
Activation Energy without enzyme
ΔGo
Free energy change
ΔEo+
Activation Energy of the catalyzed reaction
Properties of an Active Site (4)
Crevice Creates microenvironment
3D fold
Held by weak non-covalent interactions
small part of enzyme
Proximity Affect
Brings substrates closer together
Lock and Key
Enzyme Substrate Complement one another
Induced Fit
Enzyme Changes shape as substrate binds give energy to reach state
V in kinetics
Rate or change in [] of reactants or products over time
K1 in Kinetics
Rate Constant of forward reaction
K2 in kinetics
Rate constant of the reverse reaction
Michaelis Menton Shape
is a hyperbolic curve
Allosteric Enzyme Curve Shape
sigmoidal curve
At low Concentration of S what is the rate compared
The rate is proportional to the concentration of S and is first order
at high S concentration rate is compared how
At high S concentration rate is independed and zero order
What are the three michaelis Menton Assumptions
1 - formation and breakdwon are constant and so at steady state
2- product formation is irreversible
3 - K2
Km is what
the michaelis menton constant. It combines all rate constants for formation and dissappearance. It is the concentration of substrate when it is half maximum
What is the Km formula
Km = (k2+K3)/K1
What does a high Km or low Km mean
High Km means loose binding low km means tight binding
Vformation =
K1[s][E]
V breakdown =
(K2+K3)[ES]
Kcat is
the rate constant for the formation of P
Lineweaver Burke Plot Readings
X Axis - 1/[s]
Y Axis - 1/V
X intercept = -1/km
Y Intercept 1/V
Sequential Displacement
Substrate binds before product is released
Ping Pong double displacement
one or more products are released before all substrates are
Reversible Types of Inhibition and explanation
Competitive - Binds enzyme in active site and has a similar structure to substrate
non-competitive - binds to a site not the active site to change conformation of enzyme
Kinetics of Competitive Inhibitor
Km will be larger because affinity decreases
the Vmax does not change
Therefore a graph would have increasing slope on a lineweaver burke plot
