Exam 2 deck Flashcards
(36 cards)
What is kinetics the study of?
Kinetics is the study of reaction rate
what is kM
kM is the substrate concentration at which there is half the maximum velocity the higher the the kM the lower the binding affinity of the enzyme is
what is vmax
Vmax is the maximum rate of the reaction an enzyme can achieve when saturated
what is the shape of a Michaelis mento graph
hyperbolic
what is the shape of line-weaver burk plots?
linear
What is an allosteric enzyme?
- allosteric enzymes display a sigmoidal relationship
- they are regulated by there products
- they have committed steps
- they have quaternary structure with multiple active sites and regulatory sites
- can be regulated by feedback inhibition
What is coopertivity
the disruption of the T R equilibrium by the binding of substrate favors binding more substrate
How do allosteric enzymes differ from Michaelis mention enzyme?
-Michalelis menton enzymes are tertiary while allosteric enzymes are quaternary
- allosteric enzymes are more sensitive to change in substrate concentration near their Km values
- Michaelis menton has higher flux value (this makes it challenging to go from 10% vmax to 80% vmax
How do you determine the committed step of a biochemical pathway?
the first irreversible step in a metabolic pathway
What state do inhibitors stabilize?
T State
What state do activators stabilize?
R state
What is the distribution of T-R equilibrium by substrates called?
homotrophic effect
What is the disruption of the T-R equilibrium by regulators called
heterotropic effect
if affinity is higher for substrate what state is stabilized?
R state
What is a sequential model?
the sequential model proposes that subunits undergo sequential changes in structure (one at a time)
What is a concerted model?
enzymes exit in two different quaternary structures all T or all R T is tense R is relaxed
What is the equation for catalytic efficiency?
Kcat/Km
What are the 3 amino acids involved in the function of chymotrypsin
His 57, Asp 102, Ser 195
What is the role of Ser 195 and what inhibits it?
Serine 195 acts as a nucleophilic catalyst and attacks carboxyl group creating tetrahedral intermediate in acylation
DIPF inhibits it
What is the role of His 57 and what inhibits it?
act as acid base catalyst and removes proton from Ser 195.
TPCK inhibits it
What is the role of Asp 102.
Acts as approximation and orientation catalyst brings his 57 near her 195 so it can remove serines proton
What is acylation?
Part of the burst phase created acyl-enzyme intermediate
What Is deacylation?
slow release of acyl group and regeneration of free enzyme through addition of water molecule
What amino acids are involves in the s1 pocket
Gly 116, Gly 226, Trp 215, Met 192
