Enzymes MCDB108A Flashcards
enzymes are _________ and assist in the formation or rearrangement of __________ bonds without being ______ themselves.
catalysts, covalent, consumed
enzymes lower the __________ barrier to increase ______, but don’t change the ___________.
activation, kinetics, thermodynamics
enzymes bind their ______ with high _____ and _____ (induced fit model)
substrates, affinity, specificity
enzyme structure ______ upon substrate binding to the _______ _______ (conformational change)
changes, active site
enzyme activity is highly _______ in cells (availabitly, accessibility, interactions and modifications)
regulated
three common catalytic mechanisms 1)? 2)? 3)?
acid base, covalent, metal ion
enzyme convert ______ into ________
substrates, products
enzymes greatly ______ the rate of a chemical reaction
increase
enzymes ______ the activation energy (deltaG) of a chemical reaction
decrease
enzymes do not change the ________ favorability (Keq)
thermodynamic
many enzymes require _______ for activity
cofactors
_________ are coenzymes which are organic components, or vitamin derivatives like NAD+, FAD+ or metals
cofactors
enzymes _______ the transition state and thus ____ the activation barrier.
stabilize, lower
enzymes provide an ________ pathway for the product formation, which involves formation of stable reaction _________ that are ______ attached to the enzyme.
alternate, intermediates, covalently
enzymes _____ the substrates appropriately for the reaction to _______ thus reducing the ______ change of the reaction
orient, occur, entropy
enzyme active sites provide ______ of substrate relative to reactive chemical group
orientation
enzyme active sites ______ excess solvent
exclude
enzyme active sites _____ binding interactions to _____ transition state
favor, stabilize
enzyme active sites have ________ functional groups
catalytic
______ catalysis is when the nucleophile on enzyme attacks electrophile on substrate to form a transient covalent enzyme-substrate intermediation (lysozome)
covalent
_______ catalysis is a proton transfer involving water or a functional group (serine proteases)
acid base
_______ catalysis is where metals in the active site promote proper orientation of substrate and aid in redox reactions (DNA/RNA polymerases)
metal ion
substrate binding to active site causes __________ changes
conformational
conformational changes are opportunities for ________ regulation
allosteric
allosteric enzymes bind ___ from an active site but influence the binding of the _____ and therefore the rate of the reaction
far, substrate
enzyme activity is regulated by _______ and catalytic _______
bioavailability, efficiency
measure the initial rate of the reaction (Vo) so you can assume the ______ is zero, and the _____ is the total amount.
product, substrate
measure enzyme rates at a fixed amount of _____, a variable ______, where the _____ is greater than the ______.
enzyme, substrate, substrate, enzyme
the ______ is rate limiting not the substrate.
enzyme
Vmax is the maximum rate of the ________. ______more will increase the Vmax.
enzyme, adding
the turnover number is ____. it can be derived from the equation Vmax/[E]tot.
Kcat
The Km is Michaelis constant and is the ___ at half the Vmax.
substrate
a low Km means the enzyme has ______ catalytic activity at a _____ substrate concentration.
high, low
chymotrypsin is a serine protease that cleaves proteins after ______. it uses _______ catalysis and ________ hydrolysis.
W Y F, covalent, acid base
the chymotrypsin active site a catalytic ______, ______ hole, and ________ pocket.
triad, oxyanion, hydrophobic
chymotrypsin acts by ___ pulling a proton from _____ which ______ it’s pka. his then pulls a proton from ______ making it a nucleophile. then it forms a _______ bond with the peptide substrate. the ________ pocket confer specificity to W, F, Y.
asp, his, increases, serine, covalent, hydrophobic
