Lecture 12 Flashcards
protein studies
- isolate proteins from samples
- purify proteins from isolations
- visualize and size
- identify
- use/study
What leads to 2 and 3 degree structures of proteins?
R group interactions
Charge of some R groups is….
pH dependent
hydrophobic / non polar R groups
tend to fold internally
hydrophilic /polar R groups
tend to fold externally (to interact with water)
enzyme
a protein or RNA that acts as a catalyst for a chemical reaction
Enzymes make reactions…
more favourable at physiological conditions
enzyme specificity
a product of having the right shape to hold the substrate(s) and a catalytic center to facilitate the reaction
enzyme specificity may require…
cofactors like organic molecules (coenzymes) or metal ions
A–>B
isomerization
A+B–>C
condensation
A–>B+C
lysis
A+B–>C+D
complicated
reaction rate/velocity
v=(-)delta[S]/delta t
v=(+)delta[P]/delta t
Initial Velocity
measured quickly and for a short period of time (before 10% of reactants are used up)
rate can be limited by…
availability of substrate and by production of product
Under optimal conditions and with excess substrate, limiting step is…
how fast enzyme can catalyze (ES–>E+P)
substrate conc and initial velocity relationship
as substrate conc. increases, initial velocity increases
Michaelis-Menten Equation
Vo=([S]Vmax)/([S]+Km)
Km
(Michaelis constant) [S] when Vo = 1/2Vmax
Km is often neat..
the physiological conc. of the substrate in the target cell
normal (alcohol)
rate from ethanol to acetaldehyde is the same as acetaldehyde to acetic acid
allergic (alcohol)
acetaldehyde accumulates because rate is different
Vmax
the enzyme rate as we increase [S]
