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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
Temp affects on reaction velocity
rapidly increase until peak and then dro
26
pH affects on reaction velocity
extreme pH conditions affect velocity can affect ionization state of active site can denature proteins pH optimum varies
27
two types on inhibition
``` irreversible= covalent bonds reversible= inhibitors bind to enzyme through non-covalent bonds ```
28
two types of reversible inhibition
competitive and noncompetitive
29
competitive inhibitor
binds to the same site that the substrate would normally attach to
30
effects on competitive inhibition
reduce affinity= increase Km | reversed by increasing concentration of S to reach Vmax
31
example of competitive inhibitor
Statin drugs= competitively inhibit the rate-limiting step of cholesterol biosynthesis treats hyperlipidemia
32
noncompetitive inhibitor
binds at a site different from the substrate | can also bind free enzyme= prevent the reaction from occurring
33
effect of noncompetitive inhibitors
``` 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
enzyme inhibitors as drugs
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
cofactor
convert enzymes from inactive form to active
36
inactive enzyme
apoenzyme
37
active enzyme
haloenzyme
38
prostheric groups
tightly bound enzymes
39
cofactors/coenxyme examples
NADH- lactate dehydrogenase CoA- Acetyl CoA carboxylase MG2+- hexokinase
40
zymogen
proenzyme inactive precursor= activated by cleavage of one or a few specific peptide bonds usually occurs in Gogi bodies
41
Apoptosis
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
mechanisms for regulating enzyme activity
gene expression, enzyme production enzyme activity covalent modification, enzyme on or off allosteric regulation, control enzyme kinetics
43
enzymes with specialized regulatory functions can be regulated when phsiologic conditions change by? (3)
regulation of allosteric enzymes regulation of enzymes by covalent modificaiton induction and repression on enzyme synthesis
44
regulation of allosteric enzymes
consists of multiple subunits regulated by effectors (modifiers) that bind noncovalently via noncompetitive inhibition can be positive effector or negative
45
homotrophic effectors
when the substrate serves as in effector usually positive effectors ex) hemoglobin
46
other allosteric effects of hemoglobin (3)
pH pCO2 concentration of biophosphoglycerate
47
heterotropic effector
effector is different from the substrate | ex) feed back inhibition of a metabolic pathway
48
covalent modifications
addition or removal of phosphate groups from specific AA of the enzyme\ catalyzed by kinases using ATP as phosphate donor
49
two major groups of plasma enzymes
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
plasma
the fluid, noncellular part of blood | phusiologic fluid
51
serum
made in the lab
52
alteration of enzyme levels in clinical diagnosis
diesases that cause tissue damage= result in increase in release of enzymes into plasma
53
enzymes as diagnostic tools
certain enzymes are only present in specific tissues- presence in plasma indicates damage to corresponding tissue
54
isoenzymes and diseases of the heart
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
quaternary structure of isoenzymes
each isoenzyme is made up of two polypeptides in one of three combinations shoes a typical electrophoretic mobility
56
brain isoenzyme
CK=BB
57
skeletal muscle isoenzyme
MM
58
cardiac mucle isoenzyme
1/3 MB, rest MM

VP Exam 2 (10 decks)

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