Exam 2 Lecture 22 PP Pathway

Question 1

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

Answer 1

glycolysis or gluconeogenesis

Question 2

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

Answer 2

store or breakdown glucose from/to glycogen

Question 3

the _ phase makes NADPH

Answer 3

oxidative phase

Question 4

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

Answer 4

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

Question 5

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

Answer 5

lactonase (a hydrolase) opens the ring by adding water

Question 6

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

Answer 6

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

Question 7

what is the rate limiting step of phase 1 of PPP

Answer 7

glucose 6-phosphate dehydrogenase

Question 8

NAD+ is primarily used for

Answer 8

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

Question 9

NADP+ is primarily used for

Answer 9

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

Question 10

what are the 2 reasons we need NADPH?

Answer 10

1. biosynthetic; synthesis of monomers

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

Question 11

what are some biosynthesis of monomers that require NADPH?

Answer 11

• FA syn
• Cholesterol syn
• Neurotransmitter syn
• Nucleotide syn

Question 12

what are the tissues with active PPPs?

Answer 12

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

Question 13

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

Answer 13

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

Question 14

what are the 3 options for glutathione redox chemistry?

Answer 14

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)

Question 15

what happens when NADPH is under produced?

Answer 15

G6-phopsphate dehydrogenase deficiency = death of RBCs

Question 16

what are they types of erythrocyte diseases?

Answer 16

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

Question 17

Fe in heme must be _ to bind O2

Answer 17

reduced

Question 18

what other proteins can make NADPH?

Answer 18

• isocitrate dehydrogenase (3 isozymes)

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

Question 19

excessive amount of conjugated bilirubin causes _

Answer 19

jaundice

Question 20

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

Answer 20

conjugate bilirubin

Question 21

the monomer form of G6PD is active or inactive?

Answer 21

inactive

Question 22

what are the 2 active forms of G6PD

Answer 22

dimer and tetramer

Question 23

conditions favoring the inactive form of G6PD

Answer 23

high amounts of NADPH, G6P, pH

Question 24

conditions favoring the active dimer form of G6PD

Answer 24

high ionic strength (salt) and pH > 8

Question 25

conditions favoring the active tetramer form of G6PD

Answer 25

high NADP+ and low pH (<6)

Question 26

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

Answer 26

true

Question 27

the importance of G6PD and ATM

Answer 27

Hsp27 interacts with G6PD and promotes G6PD dimerization ie promotes activation

Question 28

what are the activators for G6PD regulation?

Answer 28

- dimerization - TFs for antioxidant genes - Cell cycle and synthesis activators - insulin

Question 29

what are the inhibitors for G6PD regulation?

Answer 29

- phosphorylation | - apoptosis-signaling proteins

Question 30

_ is direct correlation to activating G6PD

Answer 30

insulin

Question 31

increase in _ is not a direct correlation to activating G6PD

Answer 31

increase in EXTRACELLULAR GLUCOSE can either increase or decrease G6PD

Question 32

the _ phase shuffles carbons (4 shuffles)

Answer 32

nonoxidative

Question 33

shuffle 1: 1st of the 2 enzymes that could be used; | ribose 5-phosphate isomerase shuffles a

Answer 33

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

Question 34

shuffle 1: 2nd of the 2 enzymes that could be used; | ribulose-5-phosphate epimerase shuffles a

Answer 34

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

Question 35

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

Answer 35

xylulose-5-phosphate (5-C)

Question 36

TPP coenzyme stabilizes

Answer 36

transition state of transketolase

Question 37

shuffle 3: | transaldolase transfers _ units

Answer 37

3-C

Question 38

transaldoase is _ enzyme classification and whose transition state stabilized by

Answer 38

transaldolase is hydrolase enzyme and stabilized by Lysine side chain

Question 39

shuffle 4: | regenerates _ via gluconeogenesis pathway

Answer 39

G6P; uses F6P and GAP

Question 40

if you need NADPH from PPP, then you need

Answer 40

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

Question 41

if you need energy from PPP, then you need

Answer 41

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

Question 42

if you need nucleotides from PPP, then you need

Answer 42

- option 1: nonoxidative phase in reverse | - option 2: oxidative phase only; primary products are ribose 5-phosphate + NADPH