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VP Exam 2 > Cell bio- enzymes > Flashcards

Cell bio- enzymes Flashcards

1
Q

What are the three processes where enzymes are being used?

A

Fermentation
biotransformations
pharmaceutical industry

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2
Q

fermentation

A

transformation of raw materials such as sugar, starch in industrial mixtures such as liquors, brewing

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3
Q

biotransformations

A

transformation of defined precursors to a desired target product
ex) environmental friendly processes to treat waste

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4
Q

Pharmaceutical industry

A

synthesis and modification of antibiotics

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5
Q

major classes of enzymes- Oxidoreductases

A

catalyze reactions in which one molecule is oxidized while the other is reduced
ex) oxidases, reductases, dehydrogenases

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6
Q

major classes of enzymes- transferases

A

transfer C, N, or P containing groups

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7
Q

major classes of enzymes- Hydrolyases

A

enzymes that catalyze a hydrolic cleavage reaciton

ex) nucleases and proteases

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8
Q

major classes of enzymes- Lyases

A

catalyze cleavage of C-C, C-S, and C-N bonds

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9
Q

major classes of enzymes- isomerases

A

catalyze the rearrangement of bonds within a single molecule

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10
Q

major classes of enzymes- Ligases

A

join together two molecules in an energy- dependent process

ex) DNA ligase joins to DNA molecules

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11
Q

major classes of enzymes- polymerases

A

catalyze polymerization reactions such as the synthesis of DNA and RNA

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12
Q

major classes of enzymes- proteases

A

break down proteins by hydrolyzing bonds between AA

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13
Q

major classes of enzymes- Kinases

A

catalyze the addition of phosphate groups to molecules

very common in physiology

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14
Q

major classes of enzymes- ATPases

A

hydrolyze ATO

ex) Na, K ATPase

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15
Q

major classes of enzymes- synthases

A

synthesize molecules n anabolic reactions by condensing two smaller molecule together
ex) ATP synthase

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16
Q

major classes of enzymes- phosphatase

A

catalyze the hydrolytic removal of a phosphate group from a molecule

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17
Q

What are the 6 properties of enzymes?

A
  • active sites
  • efficiency
  • specificity
  • the presence of cofactors
  • regulation
  • location in the cell
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18
Q

Michaelis-Menten equation

A

describes how reaction velocity varies with substrate concentration
an enzyme reversibly combines with its substrate to form an ES complex that yields a product, releasing the enzyme

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19
Q

Km

A

characteristic of an enzyme and its particular substrate
reflects the affinity of the enzyme for that substrate
does not vary with enzyme concentration
equal to the substrate concentration at which the reaction velocity is 1/2Vmax

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20
Q

conclusions from Michaelis-Mentin

A

large Km= enzyme has a low affinity to the substrate

the rate of reaction is directly proportional to the enzyme concentration at all substrate concentrations

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21
Q

Order of reaction

A

first order= if S conc is lower than Km the velocity of the rxn is nearly proportional to the S conc
order zero- the rate of reaction is independent of S conc

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22
Q

Allosteric enzymes

A

don’t show Michaelis-Menten kinetics

they show a sigmoidal curve

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23
Q

What factors affect the reaction velocity?

A

substrate concentration
temp
pH

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24
Q

substrate concentration affects on reaction velocity

A

rate increases until Vmax is reached= saturation

25
Q

Temp affects on reaction velocity

A

rapidly increase until peak and then dro

26
Q

pH affects on reaction velocity

A

extreme pH conditions affect velocity
can affect ionization state of active site
can denature proteins
pH optimum varies

27
Q

two types on inhibition

A 
irreversible= covalent bonds
reversible= inhibitors bind to enzyme through non-covalent bonds
28
Q

two types of reversible inhibition

A

competitive and noncompetitive

29
Q

competitive inhibitor

A

binds to the same site that the substrate would normally attach to

30
Q

effects on competitive inhibition

A

reduce affinity= increase Km

reversed by increasing concentration of S to reach Vmax

31
Q

example of competitive inhibitor

A

Statin drugs= competitively inhibit the rate-limiting step of cholesterol biosynthesis
treats hyperlipidemia

32
Q

noncompetitive inhibitor

A

binds at a site different from the substrate

can also bind free enzyme= prevent the reaction from occurring

33
Q

effect of noncompetitive inhibitors

A 
decrease Vmax (increase conc of S doens't reverse it)
kM is unchanged= don't interfere with the binding of substrate to the enzyme
34
Q

enzyme inhibitors as drugs

A

penicillin and amocicillin inhibit enzymes that are important for bacterial cell wall synthesis
ACE inhibitors= blocks enzyme for vasoconstriction= cause vasodilation= lower blood pressure
asprion= irriversibly inhibits prostaglandin and thromboxane synthesis

35
Q

cofactor

A

convert enzymes from inactive form to active

36
Q

inactive enzyme

A

apoenzyme

37
Q

active enzyme

A

haloenzyme

38
Q

prostheric groups

A

tightly bound enzymes

39
Q

cofactors/coenxyme examples

A

NADH- lactate dehydrogenase
CoA- Acetyl CoA carboxylase
MG2+- hexokinase

40
Q

zymogen

A

proenzyme
inactive precursor= activated by cleavage of one or a few specific peptide bonds
usually occurs in Gogi bodies

41
Q

Apoptosis

A

programmed cell death. mediated by proteolytic enzymes (capases)
produces cell fragments (apoptotic bodies) that phagocytic cells can engulf before causing damage to neighboring cells

42
Q

mechanisms for regulating enzyme activity

A

gene expression, enzyme production
enzyme activity
covalent modification, enzyme on or off
allosteric regulation, control enzyme kinetics

43
Q

enzymes with specialized regulatory functions can be regulated when phsiologic conditions change by? (3)

A

regulation of allosteric enzymes
regulation of enzymes by covalent modificaiton
induction and repression on enzyme synthesis

44
Q

regulation of allosteric enzymes

A

consists of multiple subunits
regulated by effectors (modifiers) that bind noncovalently via noncompetitive inhibition
can be positive effector or negative

45
Q

homotrophic effectors

A

when the substrate serves as in effector
usually positive effectors
ex) hemoglobin

46
Q

other allosteric effects of hemoglobin (3)

A

pH
pCO2
concentration of biophosphoglycerate

47
Q

heterotropic effector

A

effector is different from the substrate

ex) feed back inhibition of a metabolic pathway

48
Q

covalent modifications

A

addition or removal of phosphate groups from specific AA of the enzyme\
catalyzed by kinases using ATP as phosphate donor

49
Q

two major groups of plasma enzymes

A

small group of enzymes: actively secreted into the blood by specific cell types
ex) liver- zymogens of enzymes involved in blood coagulation
large numer of enzymes are released from cells during normal cell turnover
mostly funciton intracellulary and have no role in plasma

50
Q

plasma

A

the fluid, noncellular part of blood

phusiologic fluid

51
Q

serum

A

made in the lab

52
Q

alteration of enzyme levels in clinical diagnosis

A

diesases that cause tissue damage= result in increase in release of enzymes into plasma

53
Q

enzymes as diagnostic tools

A

certain enzymes are only present in specific tissues- presence in plasma indicates damage to corresponding tissue

54
Q

isoenzymes and diseases of the heart

A

catalyze the same reaction but may not have same physical properties due to differences in AA sequence= may contain different numbers of charged AA= can be separated via electrophoresis
different organs contain different proportions of isoenzymes

55
Q

quaternary structure of isoenzymes

A

each isoenzyme is made up of two polypeptides in one of three combinations
shoes a typical electrophoretic mobility

56
Q

brain isoenzyme

A

CK=BB

57
Q

skeletal muscle isoenzyme

A

MM

58
Q

cardiac mucle isoenzyme

A

1/3 MB, rest MM

VP Exam 2 (10 decks)

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