Term 1- Lec 10- Enzymes

Question 1

The 6 types of enzymatic reactions

Answer 1

Hydrolases, Ligases, Lyases, Oxidoreductases, Transferases, and Isomerases

Question 2

Hydrolases

Answer 2

Cleave bonds by the addition of water

Question 3

Ligases:

Answer 3

Form bonds between C and O, S, and N coupled with hydrolysis of high energy phosphates

Question 4

Lyases:

Answer 4

Cleave C-C, C-S, and certain C-N

Question 5

Oxidoreductases:

Answer 5

Catalyse oxidation-reduction reactions

Question 6

Transferases:

Answer 6

Transfer C-, N- and P- containing groups

Question 7

Isomerases:

Answer 7

Catalyze racemization of optical or geometric isomers

Question 8

Cofactor

Answer 8

A small molecule required for the catalytic activity of an enzyme

Question 9

Coenzyme

Answer 9

An organic cofactor ie. vitamins

Question 10

Cosubstrate

Answer 10

When the cofactor only transiently binds to the enzyme

Question 11

Prosthetic group

Answer 11

When the cofactor is permanently associated with the enzyme, either covalently or non-covalently

Question 12

Holoenzyme

Answer 12

Catalytically active enzyme-cofactor complex

Question 13

Apoenzyme

Answer 13

Inactive protein lacking the cofactor

Question 14

Glycopeptidyl Transferase (GT)

Answer 14

Penecillin acts as a competitive inhibitor and covalently binds the active site, rendering it useless

Question 15

Catalysis by proximity

Answer 15

Enzyme creates local high concentration of substrates and orients them correctly for bonding

Question 16

Covalent catalysis

Answer 16

Enzyme forms a transient covalent bond with the substrate (typical in transferases)

Question 17

Catalysis by strain

Answer 17

Binds the substrate and puts it in an unfavor position to weaken the bond, making it easier to break the bond

Question 18

Mechanism for general acid-base catalysis

Answer 18

Side chains or prosthetic groups mediate proton transfer/binding between E and S/T

Question 19

Effect of substrate concentration on rxn rates

Answer 19

The rxn rate increases with concentration increase until it reaches a maximum level of saturation.

Question 20

Effect of enzyme concentration on rxn rates

Answer 20

More enzyme = faster rate

Question 21

effect of pH on rxn rate

Answer 21

environmental pH can strongly affect a rxn rate, with every enzyme having it’s own optimal pH for functioning

Question 22

Effect of denaturation on rxn rate

Answer 22

Denaturation causes enzymes to lose shape, thus function. pH, temperature, heavy metals, organic solvents, or mechanical mixing can cause it

Question 23

Effect of temperature on rxn rate

Answer 23

High temperatures increase chances of molecular colisions. At a certain high temperature, proteins begin to denature though. Low temps slow rxns.

Question 24

What does stereospecificity mean in enzymes?

Answer 24

They can tell D and L enantiomers apart and will only bind to one enantiomer of a molecule.