Amino Acids, Proteins, & Enzymes

Question 1

imino acid

Answer 1

proline is considered this because of the NH2+ group instead of NH3

Question 2

STCNQY

Answer 2

amino acids with polar side chains

Question 3

DE

Answer 3

amino acids with negatively charged (acidic) side chains

Question 4

RKH

Answer 4

amino acids with positively charged (basic) side chains

Question 5

GAVLIMP

Answer 5

amino acids that are nonpolar with nonaromatic side chains

Question 6

FWY

Answer 6

amino acids with aromatic side chains

Question 7

phenylalanine, tyrosine

Answer 7

amino acids that are essential for production of dopamine, norepinephrine, epinephrine, thryoxine, melanin

Question 8

tryptophan

Answer 8

amino acid that is essential for production of serotonin, melatonin, and vitamin b3 (niacin)
**high yield

Question 9

histidine

Answer 9

amino acid essential for production of histamine

Question 10

primary structure

Answer 10

amino acids linked together by peptide bonds, read from N to C terminus

Question 11

secondary structure

Answer 11

alpha helix, beta sheet

Question 12

cysteine

Answer 12

amino acid that forms disulfide bonds

Question 13

glycine

Answer 13

amino acid with smallest side chain, often found at bends in protein structure

Question 14

proline

Answer 14

amino acid with cyclic structure that causes a kink, often found in the bends of protein structure

Question 15

denaturation agents

Answer 15

SDS, extreme pH, high temperature

Question 16

Vmax

Answer 16

maximum rate of reaction possible, only way to increase it is to increase enzyme concentration

Question 17

1/2 Vmax

Answer 17

Substrate concentration at this point on Michaelis-Menten graph is the Km

Question 18

Km

Answer 18

michaelis constant, used to compare enzyme affinities. Lower affinity means higher this

Question 19

1/Vmax

Answer 19

y-intercept of Lineweaver-Burk plot

Question 20

-1/Km

Answer 20

x-intercept of Lineweaver-Burk plot

Question 21

antabuse

Answer 21

example of irreversible enzyme inhibitor, this is an inhibitor of alcohol dehydrogenase - makes you hold onto acetaldehyde which causes prolonged and exacerbated hangovers - used to treat alcohol addiction

Question 22

reversible inhibitors

Answer 22

most common type of enzyme inhibitors used clinically, can be competitive, noncompetitive, or uncompetitive

Question 23

competitive inhibition

Answer 23

inhibitor binds to enzyme at active site, preventing substrate from binding. E + I = EI. No ES complex forms.

• increasing [S] overcomes this type of inhibition
• *This type of inhibition increases Km (decreases affinity), Vmax unchanged

Question 24

noncompetitive inhibition

Answer 24

inhibitor binds to enzyme at site other than active site, forming EI complex. Substrate may still bind, forming EIS, but reaction cannot proceed to products.

• increasing [S] cannot overcome inhibition.
• *This type of inhibition does not change Km (affinity unchanged), but decreases Vmax.

Question 25

uncompetitive inhibition

Answer 25

inhibitor binds ES complex (not at active site), EIS forms and reaction cannot proceed to products.

• increasing [S] will make the inhibition more effective.
• *This type of inhibition decreases both Km and Vmax

The apparent Km decreases because by binding to the enzyme-substrate complex, the inhibitors are “pulling” that complex out from the reactions. This removal of substrate decreases its concentration, and allows the remaining enzyme to work better.

Question 26

sulfa drugs

Answer 26

example of using competitive inhibitor clinically for infection, this inhibits PABA and blocks bacterial production of folic acid

Question 27

cyanide poisoning

Answer 27

example of using noncompetitive inhibitor - give the patient hydroxocobalamin to turn the poison into a nontoxic substance in the body

Question 28

allosteric enzyme

Answer 28

enzyme with multiple active sites that allow for multiple types of regulation

• usually has multiple subunits with quaternary structure and multiple active sites
• Vo vs [S] plots give sigmoidal curve instead of hyperbola
• modulators of these enzymes bind to sites other than the active sites
• end products can be feedback activators or inhibitors

Question 29

isoenzymes

Answer 29

enzymes routinely measured in blood samples, tissue-specific isoforms show where cellular damage is occuring in the body. Ex: troponin - heart, CK1 - brain, CK2 - heart, CK3 - skeletal muscle, AST and ALT - heart and liver.

Question 30

high fever, drugs, sepsis

Answer 30

clinical conditions that can result in protein denaturation