PPP

Question 1

How does PPP differ from glycolysis?

Answer 1

Both are oxidation of glucose
But PPP uses NADH rather than ATP

Question 2

How does NADPH serve as an antioxidant in the cell?

Answer 2

Counters damaging effects of oxygen radicals (liver, adipose, mammary glands, adrenal galnds)

High NADPH: NADP is a reducing environment

In PPP, NADP is electron acceptor = is being reduced during oxidation of sugar

Question 3

PPP Oxidative Phase overall

Answer 3

Glucose-6-phosphate + 2NADP + H2O —> ribose 5-phosphate +co2 + 2NADPH + 2H+

1H per NADPH

Question 4

Carbon pattern for oxidative phase ppp

Answer 4

6 - 6 -6 -5 -5

4 enzymes

1. Dehydrogenase = NADP needed
2. Hydrolysis = h20
3. Dehydrogenase = NADP needed, co2 released
4. Isomerase

Question 5

Ribulose 5-phosphate structural difference

Answer 5

Carboxylic group on middle

“U in middle”

Question 6

Ribose 5 phosphate structural difference

Answer 6

Carboxylix group on top

Needs to be prepped for …..

Question 7

Transketolase ideas

Answer 7

Adds two carbons to chain

Adds ketolase double bond and up to Aldose

Question 8

Reductive phase for PPP carbon path

Answer 8

5+5–>7,3
7+3->6,4
4+5–>6,3

Question 9

PPP oxidative phase enzyme pathway

Answer 9

Dehydrogenase - co double bond
Lactonase -adds water to break long co bond and replace with oh - causes aldose
Dehydrogenase - releases aldose top as co2 - causes ketose
Isomerase - flips back to ketone

Question 10

PPP non oxidative phase enzyme pathway

Answer 10

Epimerase: Needs xylulose ketose and ribose aldose
Tpp transketolase = 2C transfer from ketose to aldose acceptor
Transaldose = 3 carbon transfer from 7C ketose to 3C aldose = 3C ketose + 6C aldose

Question 11

Big purpose of PPP

Answer 11

Cell growth, maintenance, and proliferation functions
-nucleotides
-NADPH for Lipid and amino acid synthesis
-NADPH for ROS when necessary

Question 12

If deficient in what enzyme
Then sensitive to primaquine treatment?

Answer 12

Glucose-6-phosphate dehydrogenase
Not enough NADPH available to help reduce GSSG
Allowing GSH (reduced product) to reduce peroxide

Question 13

TTP is a derivative of which vitamin?

Answer 13

B

Question 14

Difference between vitamin B and TPP structure

Answer 14

Both have N and S aromatic rings
TTP has COOH group between N and S on ring

Question 15

How many molecules of G6P are required to produce 5 molecule of F6P?

Answer 15

?

Question 16

How is PPP regulated

Answer 16

Allosteric activation of G6PD by NADP
Allosteric inhibition of G6PD by NADPH
Availability of Mg2+ and thiamine (precursors to TPP)

Question 17

What does non oxidative phase accomplish?

Answer 17

Helps restart oxidative cycle when NADPH needed (either to fight oxidative stress or for fatty acid synthesis )

Sometimes we need oxidative cycle to make nucleotide/ coenzymes = cell growth

Question 18

When a lot of NADPH is being used by cell : regulation

Answer 18

NADP+ goes up
Allosteric ally activates glucose-6-phosphate dehydrogenase
PPP Ox is activated = more NADPH produced

Question 19

If given concentrations, find favorability

Answer 19

Change in g = g standard + RTlnK

Question 20

If only the oxidative phase went forward, why would this cause problems?

Answer 20

No reverse means accumulation of ribose 5 phosphate
Means less favorability due to change in Q