Enzyme Mechanisms

Question 1

What are the four types of enzymatic regulation?

Answer 1

1) Non-covalent modification (inhibitor, activator) 2) Covalent modification (inhibitor, activator) 3) Irreversible (at the protein level) 4) Reversible ( at the protein level)

Question 2

Allostery

Answer 2

Non-covalent modification; binding of a ligand at one site of an enzyme causes differences in binding at different site; allosteric proteins usually have multiple subunits; allostery appears to modify Km.

Question 3

What four amino acid commonly phosphorylated?

Answer 3

Ser, Thr, Tyr, His

Question 4

What amino acid is commonly adenylated?

Answer 4

Tyr

Question 5

What enzyme catalyzes the addition of a phosphate group?

Answer 5

Phosphorylase

Question 6

What enzyme catalyzes the addition of AMP or an adenyl group?

Answer 6

Adenylase

Question 7

Ubiquitination

Answer 7

The process by which the protein ubiquin is added to a compound; associated with Lys; Poly marks target for degradation; Mono- changes activity

Question 8

What types of modifications are used to modify enzyme activity?

Answer 8

1) Phosphorylation, Adenylation, ubiquitination, addition of a hydrophobic group, cellular pH.

Question 9

SCCAM

Answer 9

Five Mechanisms of catalysis (Strain, Covalent, Cage-effect, Acid-base, Metal ion)

Question 10

What are the 6 enzyme classes?

Answer 10

HOT LILY; 312456; Hydrolase, Oxidoreductase, Transferase, Lyase, isomerase, ligase.

Question 11

Oxidoreductase

Answer 11

EC: 1; Mechanism of catalysis Transfer of electrons

Question 12

What are the three types of oxidoreductases?

Answer 12

1st, Oxidoreductases transfer electrons; Dehydrogenase, Oxidase, Oxygenase

Question 13

Dehydrogenase

Answer 13

Oxidoreductase; Transfer of a hydrogen from donor to acceptor

Question 14

Oxidase

Answer 14

Oxidoreductase; Transfer of hydrogen (or e-) from donor to oxygen

Question 15

Oxygenase

Answer 15

oxidoreductase; Incorporation of oxygen into a substrate

Question 16

Transferase

Answer 16

EC 2; enzyme mechanism; transfer functional groups (two types Kinase and Transaminase)

Question 17

Kinase

Answer 17

Transferase; Transfer of a phosphoryl group

Question 18

Transaminase

Answer 18

Transferase; Transfer of an amino group to a keto group

Question 19

Hydrolase

Answer 19

EC 3; Single bond cleavage by water incorporation; two types (phosphatase, sulfatase)

Question 20

Phosphatase

Answer 20

Hydrolase; Removal of phosphate groups

Question 21

Sulfatase

Answer 21

Hydrolase; Removal of sulfate groups

Question 22

Lyase

Answer 22

EC 4; Bond cleavage by elimination; naming (hydro-lase; thio-lyase.. etc.)

Question 23

Isomerase

Answer 23

EC 5; Intramolecular group transfer; two types (mutase, epimerase)

Question 24

Mutase

Answer 24

Isomerase; intramolecular group transfer

Question 25

Epimerase

Answer 25

Isomerase; conversion of chirality at one carbon atom

Question 26

Ligase

Answer 26

EC 6; Joining two molecules; ATP dependent

Question 27

Synthetase

Answer 27

Ligase; A common name for ligase.

Question 28

Nucleophile

Answer 28

a compound with a strong tendance to donate electrons

Question 29

Electrophile

Answer 29

a compound with a strong tendency to accept electrons

Question 30

Hexokinase

Answer 30

look at the suffix!! It is a kinase. A kinase is a transferase, this works in glycolysis; uses the cage effect and induced fit