Jenny - enzyme2

Question 1

covalent modification in small molecule

Answer 1

phosphrylation, acetylation, glycosylation

Question 2

covalent modification in large

Answer 2

adp-ribosylation, glutathionylation, ubiquitination

Question 3

allosteric regulation is what kind?

and how is regulated?

Answer 3

non-covalent
at least one site, separate from active site, where an allosteric activator or inhibitor can bind/alter enzyme shape and thus function

Question 4

PFK-1 is sigmoidal (S-shaped) Vo vs. [S] curve. this is due to what?

Answer 4

cooperativity of S binding

Question 5

when regulator subunit binds regulating molecule, what happen?

Answer 5

it induces change in shape, changing apparent Km and shows a sigmoidal relationship when binding is measured over different [S] => cooperativity

Question 6

interconvertible enzymes are controlled by what?

Answer 6

covalent modification

Question 7

converter enzymes catalyze what?

Answer 7

covalent modification

Question 8

product of one reaction trasnferred directly to active site of next enzyme without diffusing into the solvent

Answer 8

metabolite channeling

Question 9

different enzymes catalyzing reactions in the same pathway are bound together

Answer 9

multienzyme complex

Question 10

different activities exist on a single, multifunctional (multidomain**) polypeptide chain

Answer 10

multifunctional enzyme

Question 11

nucelophilic species are …?

Answer 11

electron rich

Question 12

electrophilic species are ….?

Answer 12

electron poor

Question 13

formation of what intermediate is characteristics of nucleophilic substitution?

Answer 13

tetrahedral intermediate

Question 14

direct displacement in nucleophihc subsitition has what?

Answer 14

transition state

Question 15

in cleavage reaction, enzymes do waht?

Answer 15

enzymes can modify substrates to temporarily generate unstable forms (C-, C+. O- etc) more susceptible to reactions

Question 16

oxidizing agent

Answer 16

gains electron (is reduced)

Question 17

reducing agent

Answer 17

donates electrons (is oxidized)

Question 18

in acid-base catalysis, general base(B:) can act as ___

Answer 18

proton acceptor

Question 19

in acid-base catalysis, general acid (BH:) can ____

Answer 19

donate protons

Question 20

in covalent catalysis, all or part of a substrate is bound covalently to the enzyme to form _____

Answer 20

reactive intermediate

Question 21

under physiological conditions, the encounter frequency is about ?

Answer 21

10^8 to 10^9 M-1s-1

Question 22

sucrose phosphorylase exhibits what?

Answer 22

covalent catalysis

glucose is transferred to enzyme then is donated to phosphate later

Question 23

Km is measure of what?

Answer 23

affinity of E for S

Question 24

Kcat?

Answer 24

Vmax/Etotal
normalize for enzyme concentration
=catalytic constant or turnover # enzyme

Question 25

Kcat/Km

Answer 25

ratio describes "catalytic efficiency" | also normalized for Km

Question 26

what is it that called "apparent second order rate constant" for the enzyme ( how well it works when substrate is not saturating)

Answer 26

Kcat/Km = catalytic efficiency

Question 27

which enzyme of ubiquitin has catalytic cysteine?

Answer 27

E1

Question 28

E1 forms what kind of bond between the Cys-SH and the COOH on the carboxyl terminal of uniquitin?

Answer 28

thioester bond

Question 29

UBE3A encoding E3 dysfunction - servere neurological/motor problems. what syndrome?

Answer 29

angelman syndrome

Question 30

VHL tumor supressor also and E3 ligase | what syndrome?

Answer 30

von hipel-lindau syndrome

Question 31

epithelial Na channel loses its ubiquitin-based regulation -> early onset hypertension what syndrome?

Answer 31

Liddle's Syndrome

Question 32

inactive enzyme precursor

Answer 32

zymogens

Question 33

binding forces for catalysis (5)

Answer 33

1. charge-charge interaction 2. H bond 3. hydrophobic interaction 4. van der waals forces 5. active site cysteine

Question 34

example of active site cysteine utilizing catalysis

Answer 34

ubiquitin-conjugating enzymes

Question 35

this is identified by covalent DFP labeling

Answer 35

ser-195

Question 36

this is identified by affinity labeling with TosPheCH2Cl

Answer 36

His-57

Question 37

this is identified by x-ray crystallography. The catalytic triad'

Answer 37

Asp-102

Question 38

essential ions?

Answer 38

mostly metal ions

Question 39

coenzymes (what kind of compound?)

Answer 39

organic compoud

Question 40

apoenzyme has what

Answer 40

protein only and inactive

Question 41

holoenzyme has what

Answer 41

cofactor with protein "active"

Question 42

larger mobile metabolic groups can be attached at ____ of the coenzyme.

Answer 42

reactive center

Question 43

many enzymes require ____

Answer 43

inorganic cations

Question 44

this enzyme has an absolute requirement or are stimulated by metal ions. (K+, Ca2+, Mg2+)

Answer 44

metal-activated enzymes

Question 45

this contains firmly bound metal ions at the enzyme active sites (ex. iron, zinc, copper, cobalt)

Answer 45

metalloenzymes

Question 46

this enzyme is in mammal and synthesized from common metabolites

Answer 46

metabolite coenzymes

Question 47

in mammal, this enzyme is derivatives of vitamins

Answer 47

vitamin-derived coenzymes

Question 48

two classes of coenzymes

Answer 48

``` cosubstrates (altered/regenerated) prosthetic groups (remain bound, covalently bound to enzyme) ```

Question 49

net reaction for dehydrogenases

Answer 49

NAD(P)+ 2e- + 2H+ -> NAD(P)H + H+

Question 50

Iron in metalloenzymes , equation

Answer 50

Fe3+ + e- (reduced substrate) -> Fe2+ +(oxidized substrate)

Question 51

Iron-sulfur clutsers can accept how many e- in a reaction?

Answer 51

1