Exam 2 Lecture 22 PP Pathway Flashcards

1
Q

if we have G6P and the enzyme G6P isomerase is working on it, this means the pathway desired is _?

A

glycolysis or gluconeogenesis

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2
Q

if we have G6P and the enzyme phosphoglucomutase is working on it, this means that the pathway desired is _?

A

store or breakdown glucose from/to glycogen

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3
Q

the _ phase makes NADPH

A

oxidative phase

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4
Q

what is the 1st of the 3 reactions for making NADPH

A

glucose-6-phosphate dehydrogenase oxidizes G6P to form a lactone as well as reduces NADP+ to form NADPH

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5
Q

what is the 2nd of the 3 reactions for making NADPH

A

lactonase (a hydrolase) opens the ring by adding water

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6
Q

what is the 3rd of the 3 reactions for making NADPH

A

6-Phosphogluconate dehydrogenase catalyzes the oxidative decarboxylation of 6-phosphogluconate to form ribose 5-phosphate and reduces NADP+ to form NADPH

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7
Q

what is the rate limiting step of phase 1 of PPP

A

glucose 6-phosphate dehydrogenase

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8
Q

NAD+ is primarily used for

A

catabolism (oxidative pathway) uses dehydrogenases; e- transport and OxPhos

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9
Q

NADP+ is primarily used for

A

anabolism (reductive pathway) uses reductases; trying to build NADP+ up for PPP

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10
Q

what are the 2 reasons we need NADPH?

A
  1. biosynthetic; synthesis of monomers

2. reducing power of NADPH for detoxification; primarily glutathione (RBCs)

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11
Q

what are some biosynthesis of monomers that require NADPH?

A
  • FA syn
  • Cholesterol syn
  • Neurotransmitter syn
  • Nucleotide syn
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12
Q

what are the tissues with active PPPs?

A
  • adrenal gland, testes, ovary (steroid syn)
  • liver, adipose tissue, mammary gland (FA syn)
  • liver also cholesterol syn
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13
Q

in the tripeptide glutathione, the gamma linkage is unique as it links the _

A

oxygen in the side chain of glutamate instead the oxygen in the backbone

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14
Q

what are the 3 options for glutathione redox chemistry?

A
  1. interactions with proteins (no enzyme needed) ie disulfide bonds
  2. inactivation of peroxides (enzyme glutathione peroxidase) ie ROS
  3. regeneration of reduced glutathione (uses NADPH to make NADP+ = substrate for PPP)
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15
Q

what happens when NADPH is under produced?

A

G6-phopsphate dehydrogenase deficiency = death of RBCs

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16
Q

what are they types of erythrocyte diseases?

A

issues with Hb, membrane/cytoskeleton defects, and metabolic errors

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17
Q

Fe in heme must be _ to bind O2

A

reduced

18
Q

what other proteins can make NADPH?

A
  • isocitrate dehydrogenase (3 isozymes)

- malic enzyme (ME1) interconverts malate and pyruvate in the cytoplasm

19
Q

excessive amount of conjugated bilirubin causes _

A

jaundice

20
Q

most severe effect of G6PDD is blood is ‘normal’ but liver cannot

A

conjugate bilirubin

21
Q

the monomer form of G6PD is active or inactive?

A

inactive

22
Q

what are the 2 active forms of G6PD

A

dimer and tetramer

23
Q

conditions favoring the inactive form of G6PD

A

high amounts of NADPH, G6P, pH

24
Q

conditions favoring the active dimer form of G6PD

A

high ionic strength (salt) and pH > 8

25
Q

conditions favoring the active tetramer form of G6PD

A

high NADP+ and low pH (<6)

26
Q

T/F: NADP+ is both a substrate and a coenzyme

A

true

27
Q

the importance of G6PD and ATM

A

Hsp27 interacts with G6PD and promotes G6PD dimerization ie promotes activation

28
Q

what are the activators for G6PD regulation?

A
  • dimerization
  • TFs for antioxidant genes
  • Cell cycle and synthesis activators
  • insulin
29
Q

what are the inhibitors for G6PD regulation?

A
  • phosphorylation

- apoptosis-signaling proteins

30
Q

_ is direct correlation to activating G6PD

A

insulin

31
Q

increase in _ is not a direct correlation to activating G6PD

A

increase in EXTRACELLULAR GLUCOSE can either increase or decrease G6PD

32
Q

the _ phase shuffles carbons (4 shuffles)

A

nonoxidative

33
Q

shuffle 1: 1st of the 2 enzymes that could be used;

ribose 5-phosphate isomerase shuffles a

A

moves a hydrogen converts ribulose-5-phosphate into ribose-5-phosphate

34
Q

shuffle 1: 2nd of the 2 enzymes that could be used;

ribulose-5-phosphate epimerase shuffles a

A

moves a hydroxyl converts ribulose-5-phosphate to xylulose-5-phosphate

35
Q

shuffle 2:

transketolase transfer 2-C from _ leaving behind glyceraldehyde-3-phosphate (3-C)

A

xylulose-5-phosphate (5-C)

36
Q

TPP coenzyme stabilizes

A

transition state of transketolase

37
Q

shuffle 3:

transaldolase transfers _ units

A

3-C

38
Q

transaldoase is _ enzyme classification and whose transition state stabilized by

A

transaldolase is hydrolase enzyme and stabilized by Lysine side chain

39
Q

shuffle 4:

regenerates _ via gluconeogenesis pathway

A

G6P; uses F6P and GAP

40
Q

if you need NADPH from PPP, then you need

A

anabolic ie biosynthesis. Uses full PPP cycle and primary product is NADPH

41
Q

if you need energy from PPP, then you need

A

glycolysis primary products are F6P + GAP ie skipping the last shuttle of PPP so can have glycolysis

42
Q

if you need nucleotides from PPP, then you need

A
  • option 1: nonoxidative phase in reverse

- option 2: oxidative phase only; primary products are ribose 5-phosphate + NADPH