enzymes

Question 1

define enzyme

Answer 1

biological catalyst that increase biochemical reaction rates without undergoing permanent changes or being consumed

Question 2

general equation for enzyme function

Answer 2

E+S->ES->E+P

Question 3

define catalyst

Answer 3

substance that accelerates the rate of chemical reaction without becoming modified itself

Question 4

define cofactos

Answer 4

non-protein substances that are essential for enzyme activity and must bind enzyme before rxns can happen

Question 5

what is another term for inorganic cofactors

Answer 5

activators

Question 6

list common activators

Answer 6

• magnesium
• chloride
• manganese
• potassium
• zinc
• calcium

Question 7

define coenzymes

Answer 7

organic substances bound to proteins that are required for enzyme function

Question 8

ture or false co enzymes are not substrates for an enzyme but participate in the reaction process

Answer 8

true

Question 9

name a common enzyme (used in many detection assays)

Answer 9

NADH

Question 10

define apoenzyme

Answer 10

protein portion of an enzyme

Question 11

define haloenzyme

Answer 11

complete, active enzyme complex

Question 12

define zymogen

Answer 12

inactive secreted form of enzyme

Question 13

define allosteric site

Answer 13

a cavity other than the active site that may bid regulatory molecules

Question 14

what rxn does oxidoreductase catalyze

Answer 14

transfer of H and O from one substrate to another

Question 15

what rxn does transferase catalyze

Answer 15

transfer of a specific group to another

Question 16

what rxn does hydrolases catalyze

Answer 16

hydrolysis of a substrate

Question 17

what rxn does isomerases catalyze

Answer 17

change of the molecular form of a substrate

Question 18

what rxn does lyases catalyze

Answer 18

non-hydrolytic removal or addition of a group to substrate

Question 19

what rxn does ligases catalyze

Answer 19

joining of two molecules by the formation of new bonds

Question 20

at what temperature are most enzymes inactivated

Answer 20

-5 celcius

Question 21

first order kinetics

Answer 21

a rxn where there is constant enzyme concentration and increasing substrate concentration

Question 22

in first order kinetics what is considered the rate limiting step

Answer 22

substrate concentration - there are open active sites remaining to be used

Question 23

excess substrate can lead to the ____ phenomenon

Answer 23

post-zone

Question 24

define zero-order kinetics

Answer 24

a rxn where all active sires are saturated with substrate
-> change in product concentration depends on enzyme concentration

Question 25

in michaelis menten curve what is Km

Answer 25

the michaelis menten constant -> measure of affinity for its substrate (lower = better)
Km is the substrate concentration where rxn is at half max velocity

Question 26

If the objective is to measure the enzyme activity, where on the initial velocity vs substrate concentration plot should the substrate concentration be fixed at?

Answer 26

zero order phase

Question 27

For a technologist to successfully determine enzyme activity, which aspect of enzyme kinetics has to be overcome to determine activity?

Answer 27

first order

Question 28

competitive inhibitors

Answer 28

inhibitor shares structural similarites w/ substrate and binds active site of enzyme, blocking substrate binding

Question 29

non competitive inhibitors

Answer 29

associates with enzyme at allosteric point and allows substrate binding but prevents product formation

Question 30

uncompetitive inhibitors

Answer 30

inhibitors binds ES complex and prevents product formation

Question 31

hook effect

Answer 31

high concentration of enzymes, false low signal due to dilution

Question 32

where is AST found

Answer 32

mostly in intracellular fluid - in cytoplasm and mitochondria

Question 33

how is AST measured

Answer 33

by measuring NADH -> NAD

Question 34

ALT

Answer 34

• distributed in liver and kidneys
• greater specificity for damaged liver tissue
• found only in cytoplasm

Question 35

how is ALT measured

Answer 35

NADH-> NAD

Question 36

in AST assay what is oxaloacetate reduced to

Answer 36

malate by malate dehydrogenase

Question 37

in ALT assay what is oxaloacetate reduced to

Answer 37

lactate by lactate dehydrogenase

Question 38

What does ALP catalyze

Answer 38

hydrolysis of substrates at alkaline pH

Question 39

true or false ALP has many isoforms including ones for the liver, bone and placenta

Answer 39

true, liver isozenyme most conentrated

Question 40

what diseases are associated with ALP

Answer 40

obstructive hepatobiliary disease
osteoblast mediated bone disease

Question 41

what are the main pancreatic enzymes

Answer 41

lipase - fat removal (injury diagnosis)
amylase - sugar removal (injury indicator)
protease - proteins

Question 42

S-amylase

Answer 42

secreted by salivary glands to digest sugar, deactivated in stomach

Question 43

P-amylase

Answer 43

secreted by acinar cells into the stomach to break down sugars once content reaches stomach

Question 44

lipase

Answer 44

only test needed in diagnosis of acute pancreatitis (enzyme exclusive to pancreas)

Question 45

what activators does lipase need

Answer 45

colipase in presence of bile salts

Question 46

creatine kinase

Answer 46

catalyzes reversible phosphorylation of creatine to creatine phosphate (energy usage)

Question 47

most common disease associated with increased lvls of CK

Answer 47

acute myocardial infraction (CK-MB)

Question 48

this is an energy source utilized by muscles

Answer 48

creatine phosphate

Question 49

enzyme historically used to assess prostate health before replacement by PSA

Answer 49

acid phosphatase