Enzyme and Cofactor Classes

Question 1

Oxidoreductases

Answer 1

Aox + Bred Ared + Box
oxidase, hydroxylase: transfer O2 atoms to water or to substrate and water;
O2–> H20
dehydrogenase, peroxidase, reductase;
oxygenase (transfer both O2 atoms to substrate;

cytochrome p450

Question 2

Common coenzymes of oxidoreductases

Answer 2

NADH, NADPH, FADH2

Question 3

Transferase

Answer 3

AB+CA+BC

name: which chemical group is transferred or what chemical is synthesized

Question 4

aminotransferase

Answer 4

transferase; transfers amine group (transaminase)

Question 5

kinase

Answer 5

transfers a phosphate group

Question 6

Synthase

Answer 6

indicates what kind of product is formed (glycogen synthase)

Question 7

Hydrolase

Answer 7

Breaks a CX bond using water
X=O, N, S
protease, esterase, phosphatase, peptidase, urease

Question 8

Lyase

Answer 8

Cleave C-C, C-O, C-S, and C-N bonds by means other than oxidation or hydrolysis;
decarboxylase, aldolase;
reverse reactions to form bonds: synthases; form C=C bonds by removing H2O from COH-CH

Question 9

isomerase

Answer 9

no atoms lost or added, only rearranged;

epimerase, racemase, mutase

Question 10

Ligase

Answer 10

Form C-C, C-S, C-O, C-N bonds and require ATP or another nucleotide;
synthetase (has T because it needs ATP)

Question 11

6 classes of enzymes

Answer 11

oxidoreductases, hydrolase, lyase, ligase, isomerase, transferase

Question 12

cofactors

Answer 12

vitamins, metal ions;

deficiency causes a range of diseases and without co-factor, respective chemical reaction cannot occur

Question 13

ATP, ADP/Pi, AMP/PPi

Answer 13

carry phosphoryl groups

Very high energy bond stores chemical energy and leads to protein phosphorylation

Question 14

NADH/NAD+

Answer 14

Shuttles electrons for redox of biological fuels, helps produce ATP

Question 15

NADPH/NADP+

Answer 15

Shuttle electrons for oxidation in biosynthesis reactions

Question 16

FADH2/FAD

FMNH2/FMN

Answer 16

Shuttle electrons for redox of biological fuels
more powerful than NAD’s: very strong oxidizing agents
Always bound to protein (prosthetic groups)

Question 17

coenzyme A

Answer 17

carries acyl group O=C-R (R=CH3 and longer)

Question 18

Biotin

Answer 18

Carries CO2 for carboxylation

Question 19

Tetrahydrofolate

Answer 19

amino acid metabolism;

carries 1 carbon unit to carbon or sulfur

Question 20

S-adenosylmethionine

Answer 20

carries methyl group to oxygen or nitrogen

Question 21

Pyridoxal phosphate

Answer 21

cofactor/coenzyme that reacts with amines (NH2, NH) to catalyze amino acid metabolism, transamination reactions

Question 22

Thiamine pyrophosphate

Answer 22

co-factor/co-enzyme that reacts with aldehydes/ketones to catalyze decarboxylation at the R group

Question 23

Protease

Answer 23

part of hydrolase group

Cysteine proteases, aspartic proteases, metalloproteases, serine proteases

Question 24

cysteine protease

Answer 24

active site requires cysteine residue;

papain, calpain, interleukin-1-b converting enzyme

Question 25

aspartic protease

Answer 25

active site requires aspartate residue
ex. pepsin, rennin, HIV protease
active at low pH

Question 26

rennin

Answer 26

aspartic protease;

inhibited by pepstatin and mimics protein substrate

Question 27

HIV protease

Answer 27

(drug target because leads to mutation–cocktail)

Question 28

metalloproteases

Answer 28

active site metal ion required
usually Zn2+, sometimes Co2+
ex. carboxypeptidase- release C terminal aa; thermolysin, collagenase, matrix metalloproteases;
inhibited by EDTA

Question 29

Serine proteases

Answer 29

Conserved Asp, Ser, His catalytic triad required;

trypsin, chymotrypsin, enteropeptidase, elastase, thrombin;

inhibited by DFP and serpins

has specificity from other AA around active site

Question 30

how do enzymes enhance rate of reaction

Answer 30

energy, concentration, orientation

Question 31

energy

Answer 31

“strain” the reactant to look more like the transition state or product; bind more tightly to transition state than to reactants or products (lower energy); changes can be subtle

Question 32

concentration

Answer 32

trap two reactants close to eachother

Question 33

orientation

Answer 33

orient two reactants so that proper regions are juxtaposed; stereospecificity