Biochemistry

Question 1

trypsin

Answer 1

cleaves C-terminal of Arg + Lys (basic AA)

Question 2

chemotrypsin

Answer 2

cleaves C-terminal of AROMATIC AA’s

Question 3

oxioreductases

Answer 3

redox reactions, oxidize
usually electron carriers NAD+

Question 4

transferases

Answer 4

transfer/move functional groups

Question 5

hydrolases

Answer 5

break down compound using H2O

Question 6

lyases

Answer 6

cleave molecule WITHOUT H2O

Question 7

isomerases

Answer 7

rearrange bonds
eg. move double bonds

Question 8

ligases

Answer 8

addition/synthesis reactions between LARGE subunits
eg. nucleic acid ligase

Question 9

cofactors

Answer 9

small inorganic or metal ions

Question 10

coenzymes

Answer 10

small ORGANIC groups
may be vitamins/derivatives
eg. NAD+, biotin

Question 11

Kcat

Answer 11

rate when enzyme is fully saturated
“turnover rate”
substrates turned / unit time (for each enzyme)
high Kcat = high V
UNCHANGED by changes in [substrate]

Question 12

michaelis menten plot

Answer 12

[s] vs velocity of rxn
v = {Kcat [E] [S]} / {Km + [S]}
high Kcat = high V
high Km = low V

Question 13

Km

Answer 13

measure of enzymes affinity for substrate
HIGH Km = LOWER affinity

Question 14

hills coefficient

Answer 14

• cooperative binding measure
• Hill’s > 1 = positive cooperative
• Hills < 1 = negative cooperative
• Hills = 0 not cooperative

Question 15

lineweaver burke plot

Answer 15

inverse of michaelis menten
Y intercept = 1/Vmax
X intercept = 1/Km
so lower Vmax = Y intercept is higher, higher Km = X intercept is closer

Question 16

competitive inhibition

Answer 16

• binds to active site
• Km = INCREASES
• Vmax = SAME
• only one where Vmax doesn’t change, can be overcome by high [S]

Question 17

noncompetitive inhibition

Answer 17

• binds to allosteric site
• Km = SAME
• Vmax = DECREASES

Question 18

mixed inhibition

Answer 18

• binds to allosteric site
• Km = increase OR decrease
• Vmax = DECREASES

Question 19

homotropic regulation

Answer 19

• Homotropic regulation is when a molecule serves as a substrate for its target enzyme and as a regulatory molecule of the enzyme’s activity.
• O2 is a homotropic allosteric modulator of hemoglobin.
• The four subunits of hemoglobin bind to oxygen cooperatively

Question 20

suicide inhibition

Answer 20

• ONLY TYPE that is irreversible
• Suicide inhibition occurs when an enzyme binds the inhibitor (structurally a substrate analogue) and forms an irreversible complex with it, usually through a covalent bond