Enzyme as catalysts

Question 1

enzyme active sites are ______ for a substrate

Answer 1

specific

Question 2

6 enzyme classes

Answer 2

oxidoreductases
transferases
hydrolases
lysases
isomerases
ligases

Question 3

what does the enzyme class depends on?

Answer 3

on the overall scheme

Question 4

in a serine protease, different aa residues may carry out _______ of _____ of ser-195 than those recognize the substrate

Answer 4

in a serine protease, different aa residues may carry out catalysis of OH of ser-195 than those recognize the substrate

Question 5

The first event after binding the correct substrate in the correct orientation is attack by the sidechain of the ____________

Answer 5

Ser-195 residue

Question 6

Ser-195

Answer 6

unusually reactive by its interactions with other residues in the protein

Question 7

distal in the amino acid sequence of the protein in a serine protease rxn

Answer 7

histidine and aspartate

Question 8

recognizes peptide substrates with bulky hydrophobic aa residues

Answer 8

chymotrypsin

Question 9

recognizes positively charged residues

Answer 9

trypsin

Question 10

recognizes small aa that are prevalent in elastin

Answer 10

elastase

Question 11

negative change in gibbs free energy

Answer 11

reaction proceeds spontaneously

Question 12

build

Answer 12

anabolic

Question 13

break-down

Answer 13

catabolic

Question 14

__________ and _____ are constants and have the same descriptive information for a given reaction

Answer 14

the equilibrium constant (Keq) and delta G not

Question 15

is the delta G under standard conditions

Answer 15

delta G not

Question 16

Q=Keq

Answer 16

reaction is at equilibrium

Question 17

Q>Keq

Answer 17

reaction goes in reverse

Question 18

Q

Answer 18

reaction goes forward

Question 19

a high energy catabolic rxn with a lower energy anabolic rxn resulting in synthesis of a needed compound

Answer 19

couple rxn

Question 20

enzymes help obtain equilibrium more quickly by

Answer 20

stabilizing the transition state

Question 21

how do enzymes work?

Answer 21

change the rate at which equilibrium is achieved

Question 22

enzymes change the

Answer 22

change delta G‡ for the reaction, but not delta Gº or delta G.

Question 23

measures the substrate concentration needed for 50% of the max. velocity of the rxn

Answer 23

50%

Question 24

maximal activity for a sample

Answer 24

Vmax

Question 25

_____ samples will have more enzyme, and therefore a ______ Vmax

Answer 25

Larger samples will have more enzyme and therefore a higher Vmax

Question 26

measures the catalytic power of an enzyme and it is the Vmax per amount of enzyme

Answer 26

Kcat

Question 27

the amount of product formed over unit time

Answer 27

velocity

Question 28

the more substrate there is, the ______ the enzymatic activity until one reaches _____

Answer 28

The more substrate there is, the higher the enzymatic activity until one reaches Vmax

Question 29

best for measuring substrate levels with a given amount of enzyme

Answer 29

low substrate levels relative to the Km

Question 30

would give the highest activity , and this the best to measure enzymatic activity in a sample

Answer 30

high substrate levels

Question 31

1/v is plotted versus 1/[S]

Answer 31

lineweaver-burk plot

Question 32

in the lineweaver-burk plot km is

Answer 32

always a positive number

Question 33

can be caused by lack of enzyme, defective enzyme, or lack of substrate(s) or cofactor

Answer 33

deficiency of enzyme activity