Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Catalysts

A

do not impact thermodynamics of the biological reaction (deltaHrxn, deltaG and equilibrium position)

they help the reaction go at a faster rate

lower activation energy

not changed/consumed

are pH and temp sensitive

reaction specific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Enzyme Specificity

A

a given enzyme will only catalyze a single reaction/class of reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Oxidoreductases

A

catalyze oxidation-reduction reactions (transfer electrons)

Cofactor: NAD+/NADP+

reductant: electron donor
oxidant: electron acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Transferases

A

catalyze the movement of a functional group from onemolecule to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Kinases are a form of ____ which catalyze the ______ to another molecule.

A

transferase

transfer of a phosphate group from ATP to another molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Hydrolases

A

catalyze the breaking of a compound into two molecules by ADDING water

named for their substrate (what they cleave)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Lyases

A

catalyze the cleavage of a single molecule into two products

DO NOT REQQUIRE WATER OR ACT AS OXIDOREDUCTASES

can do both breaking into two or building into one (synthases)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Isomerases

A

catalyze the arrangement of bonds within a molecule, specifically stereoisomers and constitutional isomers

can be classsidied as oxidoreductases, transferases or lyases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Ligases

A

catalyze the addition/synthesis reactions between large similar molecules and require ATP

nucleic acid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Endergonic Reaction

A

requires energy input (delta G > 0) betweej produce/reactant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Exergonic

A

energy is given off (delta G < 0) between product/reactants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Activation Energy

A

catalysts lower this to make it easier for the substrate to reach the transition state.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Enzymes may act to provide a _______ in terms of charge pH, stabalize _______ or bring reactive groups near to each other in the active site.

A

favorable microenviornment

stabilize transition state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Formation of the _______ complex in the ____ of an enzyme is the key catalytic activity of the enzyme, which reduces the _____ of the reaction.

A

enzyme-substrate

active site

activation energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

_____ , ______, and ______ within the active site all stabilize this spatial arrangement and increase efficiency of the enzyme.

A

hydrogen bonding, ionic interactions, transient covalent bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Lock and Key Theory

A

enzymes active site is already in appropriate conformation for the substrate to bind, no alteration of the substrates/enzyme structure is required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Induced Fit Model

A

endergonic and requires energy where substrate goes to active site and the shapes are altered to induce a fit and allow for correct binding to the site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Cofactos and coenzymes bind to the ______ of the enzyme and participate in the ____ of the reaction and are recruited only when needed.

A

active site

catalysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Apoenzymes/Holoenzymes

A

enzymes without their cofactors

enzymes containing them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Prosthetic Groups

A

tightly bound cofactos or coenzymes necessaryfor enzyme function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Cofactors

A

inorganic molecules/metal ions often ingested

22
Q

Coenzymes

A

small organic groups such as NAD+, FAD, CoA

water soluble vitamins like B complex and C

23
Q

Fat soluble vitamins, ______, are better regulated by partition coefficients which quantify the ability of a molecule to dissolve in ____ vs ______ environment.

A

A, D, E, K

polar

non polar

24
Q

Metabolic reactions often require _____, NAD+ (derived from _____) and biotin (derived from ______ )

A

magnesium

B3

B7

25
Q

The concentrations of substrate and enzyme greatly affect how ____ a reaction occurs.

A

quickly

26
Q

The only way to increase Vmax is by ____ the ____ concentration.

A

increasing

enzyme

27
Q

Michaelis-Menten

A

describes the rate of reaction depends on concentration of both enzyme and substrate to form product

V =( vmax*[S] ) /( Km + [S] )

28
Q

When v = 1/2 (reaction rate) vmax, then Km ___ [S]

A

equals

29
Q

Km

A

the substrate concentration at which half the enzymes active sites are full

it is the Michaelis constant

intrinsic property

30
Q

When comparing two enzymes, the one with the higher Km has the ______ for its substrate as it requires a _____ to be half saturated.

A

lower affinity

higher substrate concentration

31
Q

When substrate concentration is ___ than Km, changes in substrate concentration will greatly affect the reaction rate.

At high substrate concentrations exceeding Km, the reaction rate increases much slowly as it approaches vmax, meaning it is ____ of substrate concentration

A

lower

independent

32
Q

Lineweaver-Burk Plots

A

x-intercept : - 1/Km

y intercept = 1/vmax

useful when determining the type of inhibition of an enzyme as vmax and Km can be compared properly

33
Q

Cooperative Enzymes

A

sigmoidal shape when looking at v vs. substrate concentration

multiple subunits and active sites

T and R states

34
Q

Low affinity T state (tense)

High Affinity R state (relaxed)

A

binding of substrate encourages transition of other T subunits to R state to increase substrate binding to the other

loss of substrate can cayse R to T state transition and cause other subunits to go back to T state

35
Q

Enzymes showing cooperative kinetics are often _______ in pathways like phosphofructokinase-1 in glycolysis.

A

regulatory enzymes

36
Q

The activity of an enzyme is heavily influenced by its environment, in particular:

A

temperature
pH
salinity

37
Q

Affect of Temperature on Enzymes

A

enzyme catalyzed reactions tend to double for every 10 degree celsius increase until optimum temperature is reached (in human body this is 37 degrees or 98.6)

at higher temperatures the enzyme will denature. Some enzymes may regain function at cooler temperatures.

38
Q

Affect of pH on Enzymes

A

affects ionization of the active site ad can lead to denaturation of the enzyme

optimal pH is 7.4 (blood pH)

39
Q

Exceptions to the physiological pH are in the ______ for Pepsin at pH 2 in the _____ and ______ which work around 8.5

A

digestive tract

stomach

pancreatic enzymes

40
Q

Affect of Salinity on Enzymes

A

cam change enzyme activity in vitro by disrupting H and ionic bonds and partial change in conformation of enzyme…leading to denaturing

41
Q

Feed-Forward

A

less often, enzymes are regulated by intermediates preceding the enzyme in pathway

42
Q

Negative Feedback

A

feedback inhibition

once enough of a given product is made, pathway is turned off to prevent too much product being made

product may bind to the active site of an enzyme to inhibit them

43
Q

Competitive Inhibition

A

involves occupancy of the active site

can be overcome by adding more substrate so it out numbers the amount of inhibitor

Vmax = same

Km INCREASES as mroe substrate is required

both intersect at the y-axis

44
Q

noncompetitive Inhibitiron

A

bind to an allosteric site instead of active site to change enzyme conformation

cannot be overcome by adding mroe substrate as it is non competitive

bind equally to Enzyme and ES complezes unlike mixed inhibitors

vmax DECREASES as less enzyme avialble

Km = same as affinity for Substrate by enzymes unaffected is the same

intersect at x -axis on left hand plane

45
Q

Mixed Inhibition

A

inhibitor binds to either E or ES but has a different affinity for each

bind at allosteric site

If prefer E state: Km INCREASES (lower affinity)
If prefer ES state: Km DECREASES (higher affinity)

vmax is decreased

intersect not on the axis

46
Q

Uncompetitive Inhibition

A

bind only to the ES complex and lock the substrate to the Enzyme

afinnity for substrate is increased

bind at allosteric site

lowers Km and Vmax

parallel lines

47
Q

Irreversible Inhibition

A

active site is made unavailable for a long time or the enzyme is permanently altered

48
Q

Allosteric Enzymes

A

have multiple binding sites

alternate between active and inactive form

molecules that bind to allosteric site are allosteric activators/inhibitors that cause a conformational shift that either makes active site more readily available or less available.

49
Q

Covalently Modified Enzymes

A

activated/deactivated by phosphorylation/dephosphrylation

glycosylation by attaching sugar moieties

50
Q

Zymogens

A

Enzymes that are not tightly controlled are secreted as inactive zymogens which contain a catalytic and regulatory domain. Once regulatory domain is altered or removed, then active site is exposed for function

-ogen ending

apoptotic enzymes have similar regulation

Biochemistry (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions