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biochem > ch 13 > Flashcards

ch 13 Flashcards

1
Q

oxidoreductases

A

an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually utilizes NADP+ or NAD+ as cofactors.

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2
Q

transferases

A

enzyme that catalyze the transfer of specific functional groups from one molecule to another.

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3
Q

hydrolases

A

enzymes that are commonly used as biochemical catalysts utilizing water to break a chemical bond in order to divide a large molecule into two smaller ones.

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4
Q

lyases

A

an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bonds by means other than hydrolysis

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5
Q

isomerases

A

an enzyme that catalyzes the conversion of a specified compound to an isomer.

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6
Q

ligases

A

a ligase is an enzyme that can catalyze the joining (ligation) of two large molecules by forming a new chemical bond.

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7
Q

what is vmax

A

maximal reaction rate or velocity of an enzymatically catalyzed reaction when the enzyme is saturated with its substrate

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8
Q

why does vmax occur or why does the reaction plateau?

A

the active site is saturated with substrate

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9
Q

what is Km

A

the substrate concentration at half of the Vmax (measure of how tight an enzyme to a substrate)

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10
Q

from an evolutionary standpoint, why would an enzyme have adapted to have those different Km values?

A

the natural concentration of a substrate is reflected by the body: low Km: enzyme binds very tightly (low sub conc) high Km: enzyme binds losely (higher sub conc)

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11
Q

what is the Kcat

A

Vmax/Et the rate of the substrate being made into product unit (1/sec)

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12
Q

what is the turnover number?

A

how much product is being formed per unit enzyme per unit time when the enzyme is fully saturated with substrate

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13
Q

Catalytic efficiency

A

ratio of Kcat to Km

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14
Q

what is the significance of Kcat/Km

A

gives us the catalytic efficiency

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15
Q

low km is what

A

higher affinity

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16
Q

x intercept for a linegraph is what

A

x=-1/km

17
Q

y intercept for a linegraph

A

y=1/vmax

18
Q

competitive inhibitor

A

resembles the substrate and therefore also binds to the active site of an enzyme decreasing the amount of binding of the substrate or ligand to enzyme. BINDS TO THE ACTIVE SITE

19
Q

uncompetitive inhibitor

A

binds to a different site of the enzyme AFTER the enzyme-substrate complex has formed thus preventing the ES complex from forming product. RARE

20
Q

noncompetitive inhibitor

A

binds to a different site of the enzyme and changed the structure of the enzyme; thus blocking the enzyme from binding to substrate which stops enzyme activity.

21
Q

what do all three inhibitors have in common?

A

ITS REVERSIBLE! REVERSIBLE COVALENT BOND

22
Q

what is the km and vmax of a competitive inhibitor

A

km higher vmax same

23
Q

what is the km and vmax of an uncompetitive inhibitor

A

km lower vmax lower

24
Q

what is the km and vmax of a noncompetitive inhibitor

A

pure: km same vmax lower

25
Q

what makes an irreversible inhibitor irreversible?

A

it makes a covalent bond that is irreversible

26
Q

acid catalyst works best at what pH

A

lower Ph’s

27
Q

basic catalyst works best at what ph

A

higher Ph’s

28
Q

why is aspirin irreversible effect only last a few hours in the body?

A

body synthesizes more enzyme

29
Q

the irreversible inhibitor is similar in kinetics to what reversible inhibitor

A

noncompetitive inhibitor

30
Q

to be effective enzymes must be present at the same concentration as their substrate

A

false

31
Q

enzymes increase the equilibrium constant for the reaction thus favoring product formation

A

false

32
Q

enzymes increase the rate at which substrate is converted to product

A

true

33
Q

enzyme ensure that all substrate is converted to product.

A

false

34
Q

enzymes ensure that all product is more thermodynamically stable than the substrate

A

false

35
Q

what do the lines in a lineweaver burk plot look like for competitive inhibition

A

they are perpendicular, theyre crossed

36
Q

what do the lines in a lineweaver burk plot look like for uncompetitive inhibition

A

they are parallel, they do not cross

37
Q

what do the lines in a lineweaver burk plot look like for noncompetitive inhibition

A

they start from the same point on the xaxis, they meet at the x axis

38
Q

what is the diffusion rate for best efficiency

A

10^8 or 10^9 m-1 s-1

39
Q

what slope for lineweaver plot

A

km/vmax

biochem (9 decks)

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