Enzymology

Question 1

enzyme

Answer 1

a protein molecule that accelerates a specific chemical reaction

Question 2

active site

Answer 2

the region of an enzyme that binds the substrate during the reaction

Question 3

substrate

Answer 3

the reactant(s) in an enzyme-catalysed reaction

Question 4

lock and key model

Answer 4

ligand binding sites are rigid & complementary to shape of ligand

Question 5

induced fit model

Answer 5

flexible interaction between the ligand & active site; ligand induces a conformational change in active site

Question 6

Cahn-Ingold-Prelog (CIP) priority rules

Answer 6

atoms of higher atomic number bonded to a chiral centre are ranked above those of lower atomic number

Question 7

oxidoreductases

Answer 7

Transfer of H & O atoms or electrons from one substrate to another. Alcohol dehydrogenase.

Question 8

transferases

Answer 8

Transfer of functional groups from one compound to another. Hexokinase.

Question 9

enzyme nomenclature

Answer 9

1st number = 1 of 6 main divisions/classes of enzymes. 2 = subclass. 3 = sub-subclass. 4 = serial number.

Question 10

6 main divisions of enzymes

Answer 10

oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases

Question 11

holoenzyme

Answer 11

catalytically active enzyme-cofactor complex

Question 12

apoenzyme

Answer 12

inactive enzyme (absence of cofactor)

Question 13

[S] > Km

Answer 13

ES favoured over E + S

Question 14

[S] < Km

Answer 14

E + S favoured over ES

Question 15

hapten

Answer 15

a small molecule which, when combined with a larger carrier such as a protein, can elicit the production of antibodies which bind specifically to it

Question 16

sulfanilamide

Answer 16

antibiotic useful in treatment of kidney infection. Structural analogue of PABA (which is structural part of folic acid)

Question 17

sulfanilamide competitively inhibits…

Answer 17

bacterial dihydrofolate synthetase (which

Question 18

uncompetitive inhibition

Answer 18

inhibitor binds to enzyme-substrate complex (NOT to free enzyme). Doesn’t bind to active site but can cause distortion of active site.

Question 19

competitive inhibitors act by…

Answer 19

reducing the concentration of free enzyme available for substrate binding

Question 20

alkaline phosphatase

Answer 20

catalyses release of inorganic phosphate from phosphate esters. Uncompetitively inhibited by phosphate.

Question 21

alkaline phosphatase found in

Answer 21

liver, bile ducts, intestine, bones, kidneys, placent, leukocytes

Question 22

larger L value means that T-R equilibrium lies…

Answer 22

further toward T state. (MWC model)

Question 23

n (in MWC model) = amount of substrate that can bind.

Answer 23

the higher the n value, the more the equilibrium can be shifted toward R state