Enzymes

Question 1

MM Kinetics

Answer 1

Lower Km = greater affinity for the substrate

Question 2

What affects enzymatic rate?

Answer 2

Enzyme concentration
Substrate concentration
Temp
pH
Activators
Inhibitors

Question 3

Enzymatic methods

Answer 3

Any physical or chemical property that can relate to substrate or product concentration

Question 4

Enzymatic method categories

Answer 4

Viscosity
Titration
Chromatography
Absorbance spec
Fluorimetry
Monometric

Question 5

Coupled reactions

Answer 5

Two or more enzymatic reactions
Indicating and measuring
S1 → P1
P1 → P2

Question 6

Sulfites

Answer 6

Enhance flavor
Preserve freshness
Slow bacterial growth
Prevent oxidation and browning
Beer, wine, fruit juices

Question 7

Sulfite enzymatic test

Answer 7

Sulfite oxidase converts to sulfate
NADH peroxidase converts H2O2 to Nad+
Amount of sulfite is proportional to amount of NADH oxidized

Question 8

Glucose enzymatic test

Answer 8

Glucose oxidase
Converts glucose to lactone

Peroxidase
Converts H2O2 to oxidized dye

Oxidized dye is a colored product

Question 9

Starch and dextrins enzymatic test

Answer 9

Amyloglucosidase cleaves alpha 1,4 and 1,6 bonds
Starch, glycogen, dextrins
Liberates glucose

Question 10

Lactose enzymatic test

Answer 10

Hydrolyzed to glucose and galactose
NADH is the end product
Fast, selective, accurate

Question 11

Malic acid enzymatic test

Answer 11

Only L malic is natural
Mixture of D and L in synthetic
Measure NADH via change in absorbance

Question 12

Peroxidase test

Answer 12

Treatment that destroys peroxidase is adequate to destroy other enzymes and microbes
Shows how well food is processed

Question 13

Peroxidase enzyme

Answer 13

Heat stable
Produces brown pigments
Destroyed by blanching

Question 14

Peroxidase reaction

Answer 14

Add guaiacol and H2O2 to form colored product
High enzyme activity = oxidation

Question 15

ALP

Answer 15

Alkaline phosphatase
Heat stable enzyme in milk
Thermal stability > non spore forming pathogens

Question 16

ALP test

Answer 16

Determine if pasteurization was performed correctly

Question 17

ALP: Scharer variation

Answer 17

ALP cleaves phosphate of reagent
Creates indophenol
Blue color

Question 18

ALP: Rutgers variation

Answer 18

Phenolphthalein dye as a reagent
End with a pink color if there is enzyme activity

Question 19

Immunoassays

Answer 19

Antibody antigen interaction
Detect allergens or GMOs
High specificity for target antigen

Question 20

Epitope

Answer 20

Specific region bound by a single antibody

Question 21

ELISA

Answer 21

Enzyme linked immunosorbent assay
Binding of soluble antigen or antibody to a solid support
Bound and unbound molecules separated via washing
Enzyme label converts colorless substrate to colored product

Question 22

Sandwich method

Answer 22

Antibody attached to surface
Add sample
Antibody recognizes and captures the substance/antigen
Wash
Add a second antibody w/ enyzme
Wash
Add the substrate to the enzyme

Question 23

ELISA applications

Answer 23

Pesticide residue
Detect foodborne pathogens
Detect toxins
Meat and fish species identification
Food allergens
GMOs

Question 24

Meat species identification kits

Answer 24

Cooked and uncooked product
Qualitative
Sensitive and specific

Question 25

Lateral flow immunoassay pros

Answer 25

Sensitive and specific Low sample volume No wash steps Short time Low cost Simple

Question 26

Lateral flow immunoassay

Answer 26

Test strip Add sample Moves in certain direction Test and control lines Antibodies embedded in the strip capture the antigens Positive or negative result

Question 27

ELISA enzyme tags

Answer 27

Horseradish peroxidase ALP