8 Enzyme

Question 1

enzyme classes

Answer 1

Oxidoreductase
Transferase
Hydrolase
Lyases
Isomerase
Ligase

Question 2

oxidoreductase

Answer 2

catalayzes oxidation and reduction.

oxidase: catalase, peroxidase, tyrosinase, ascorbic acid oxidase, lipoxygenase

dehydrogenase: acting on hydrogen as donor: succinate dehydrogenase, lactic dehydrogenase

Question 3

succinate dehydrogenase

Answer 3

breaks glutamic acid into ketoglutaric acid and NH3

Question 4

lactic dehydrogenase

Answer 4

breaks lactic acid to pyruvic acid

Question 5

transferase

Answer 5

transfer radical or functional group

Question 6

hydrolase

Answer 6

catalyze hydrolysis or breaking of substrate by involving water

Question 7

lipase, glycosidase, aminopeptidase (protease), urease

Answer 7

• lipase: hydrolyzes ester bond in glyceride to produce glycerol and fatty acid
• glycosidase: hydrolyzes glycosidic bond in glycoside

Question 8

isomerase

Answer 8

atom rearrangement produces isomer.

Question 9

aldose-ketose isomerization

Answer 9

corn syrup production using isomerase (glucose to fructose)

Question 10

bromelain facilitates hydrolysis of protein

Answer 10

hydrolysis cuts molecule by adding water

Question 11

collagen protein + H2O -> pake bromelain -> amino acid

Answer 11

meat tenderizer

Question 12

lock and key

Answer 12

so specific, active site of enzyme complements the shape of the specific substrate before binding

Question 13

induced fit model

Answer 13

shape of the active site complements shape of specific substrate right after binding

Question 14

factors affecting enzyme activity

Answer 14

1. environmental conditions
2. substrate concentration
3. cofactors and coenzymes
4. enzyme inhibitors

Question 15

enzyme inhibitor such as a-glucosidase inhibited by phenol, oxalic acid inhibit succinate

Question 16

environmental conditions

Answer 16

temperature, pH, Aw, ionic concentration

Question 17

optimum temperature for enzyme 45-55

Question 18

most enzyme optimum at 30c, fully denatures at 70c

Question 19

optimum pH of enzyme activity 4.5-8

Question 20

effect of pH on enzyme activity

Answer 20

extreme pH level causes denaturation -> structure of enzyme is changed -> active site is distorted

Question 21

at low Aw (0.2), mobile water isn’t available. enzymatic reactions tend to be surpressed in the lower regions of sorption isotherm. higher Aw is preferred

Question 22

lipoxygenase in soybean causes off flavor activated after water addition

Question 23

salting in increases enzyme solubility -> increases activity

Question 24

salting out decreases enzyme solubility, decreases acttivity

Question 25

allosteric enzymes have additional site beside active site (allosteric site)

Question 26

binding of non-substrate molecule to allosteric site functions to influences the activity of the enzyme (allosteric modulator)

Answer 26

allosteric activator: increase E activity

Impair E activity: allosteric inhibitor

Question 27

binding of substrate to an enzyme’s active site affects the binding of substrate to other active sites

Answer 27

sigmoidal curve

Question 28

MSG production by corynebacterium glutamicum with the aid of allosteric enzyme

Question 29

types of inhibition

Answer 29

competitive, noncompetitive, uncompetitive, irreversible

Question 30

irreversible inhibition”

Answer 30

binds irreversibly through covalent bond, permanently inactivating the enzyme. Vmax decreaes, Km stays.

Question 31

lipoxigenase enzyme is inhibited by

Answer 31

enzyme inactivation, low pH, fat extraction

Question 32

shorter chain of protein means great thickening ability. longer chain isn’t good to thicken food product.

Question 33

concentration of sugar in wheat flour is limited -> addition a-amylase hydrolize amylose which produces maltose for fermentation -> saccharomyces cereviceae to increase CO2 and ethanol production 0> hgiher volume and bigger size