Enzymes MCDB108A

Question 1

enzymes are _________ and assist in the formation or rearrangement of __________ bonds without being ______ themselves.

Answer 1

catalysts, covalent, consumed

Question 2

enzymes lower the __________ barrier to increase ______, but don’t change the ___________.

Answer 2

activation, kinetics, thermodynamics

Question 3

enzymes bind their ______ with high _____ and _____ (induced fit model)

Answer 3

substrates, affinity, specificity

Question 4

enzyme structure ______ upon substrate binding to the _______ _______ (conformational change)

Answer 4

changes, active site

Question 5

enzyme activity is highly _______ in cells (availabitly, accessibility, interactions and modifications)

Answer 5

regulated

Question 6

three common catalytic mechanisms 1)? 2)? 3)?

Answer 6

acid base, covalent, metal ion

Question 7

enzyme convert ______ into ________

Answer 7

substrates, products

Question 8

enzymes greatly ______ the rate of a chemical reaction

Answer 8

increase

Question 9

enzymes ______ the activation energy (deltaG) of a chemical reaction

Answer 9

decrease

Question 10

enzymes do not change the ________ favorability (Keq)

Answer 10

thermodynamic

Question 11

many enzymes require _______ for activity

Answer 11

cofactors

Question 12

_________ are coenzymes which are organic components, or vitamin derivatives like NAD+, FAD+ or metals

Answer 12

cofactors

Question 13

enzymes _______ the transition state and thus ____ the activation barrier.

Answer 13

stabilize, lower

Question 14

enzymes provide an ________ pathway for the product formation, which involves formation of stable reaction _________ that are ______ attached to the enzyme.

Answer 14

alternate, intermediates, covalently

Question 15

enzymes _____ the substrates appropriately for the reaction to _______ thus reducing the ______ change of the reaction

Answer 15

orient, occur, entropy

Question 16

enzyme active sites provide ______ of substrate relative to reactive chemical group

Answer 16

orientation

Question 17

enzyme active sites ______ excess solvent

Answer 17

exclude

Question 18

enzyme active sites _____ binding interactions to _____ transition state

Answer 18

favor, stabilize

Question 19

enzyme active sites have ________ functional groups

Answer 19

catalytic

Question 20

______ catalysis is when the nucleophile on enzyme attacks electrophile on substrate to form a transient covalent enzyme-substrate intermediation (lysozome)

Answer 20

covalent

Question 21

_______ catalysis is a proton transfer involving water or a functional group (serine proteases)

Answer 21

acid base

Question 22

_______ catalysis is where metals in the active site promote proper orientation of substrate and aid in redox reactions (DNA/RNA polymerases)

Answer 22

metal ion

Question 23

substrate binding to active site causes __________ changes

Answer 23

conformational

Question 24

conformational changes are opportunities for ________ regulation

Answer 24

allosteric

Question 25

allosteric enzymes bind ___ from an active site but influence the binding of the _____ and therefore the rate of the reaction

Answer 25

far, substrate

Question 26

enzyme activity is regulated by _______ and catalytic _______

Answer 26

bioavailability, efficiency

Question 27

measure the initial rate of the reaction (Vo) so you can assume the ______ is zero, and the _____ is the total amount.

Answer 27

product, substrate

Question 28

measure enzyme rates at a fixed amount of _____, a variable ______, where the _____ is greater than the ______.

Answer 28

enzyme, substrate, substrate, enzyme

Question 29

the ______ is rate limiting not the substrate.

Answer 29

enzyme

Question 30

Vmax is the maximum rate of the ________. ______more will increase the Vmax.

Answer 30

enzyme, adding

Question 31

the turnover number is ____. it can be derived from the equation Vmax/[E]tot.

Answer 31

Kcat

Question 32

The Km is Michaelis constant and is the ___ at half the Vmax.

Answer 32

substrate

Question 33

a low Km means the enzyme has ______ catalytic activity at a _____ substrate concentration.

Answer 33

high, low

Question 34

chymotrypsin is a serine protease that cleaves proteins after ______. it uses _______ catalysis and ________ hydrolysis.

Answer 34

W Y F, covalent, acid base

Question 35

the chymotrypsin active site a catalytic ______, ______ hole, and ________ pocket.

Answer 35

triad, oxyanion, hydrophobic

Question 36

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.

Answer 36

asp, his, increases, serine, covalent, hydrophobic