Shunts

BPG shunt is also called?

Rapoport-Luebering cycle

BPG shunt is supplementary to?

Glycolysis

Main purpose of BPG shunt?

Generate 2,3-BPG

Percentage of RBC glucose entering BPG shunt?

15-25%

Main tissue using BPG shunt?

RBCs

2,3-BPG is produced from what glycolytic intermediate?

1,3-bisphosphoglycerate

Enzyme converting 1,3-BPG to 2,3-BPG?

Bisphosphoglycerate mutase

Enzyme converting 2,3-BPG to 3-phosphoglycerate?

Bisphosphoglycerate phosphatase

2,3-BPG binds which form of hemoglobin?

T-state deoxyHb

2,3-BPG binds where on Hb?

β-chain cavity

Amino acids involved in BPG salt bridges?

Val, Lys, His

Effect of 2,3-BPG on Hb?

Decreases O₂ affinity

2,3-BPG stabilizes which Hb form?

Deoxyhemoglobin

HbF binds BPG strongly or weakly?

Weakly

Why does HbF bind BPG weakly?

Histidine replaced by serine

HbF oxygen affinity compared with HbA?

Higher

High altitude causes increase in?

RBCs and 2,3-BPG

Effect of increased BPG at high altitude?

↑ O₂ release to tissues

Low pO₂ stimulates synthesis of?

2,3-BPG

Pentose phosphate pathway is also called?

Hexose monophosphate shunt

Main function of PPP?

Generate NADPH and ribose-5-phosphate

Major tissues using PPP?

Liver and RBCs

Approximate glucose metabolized by PPP in liver/RBCs?

30%

Main reducing currency generated by PPP?

NADPH

Main nucleotide precursor produced by PPP?

Ribose-5-phosphate

Does NADPH produce ATP?

No

NADH mainly functions in?

ETC and ATP production

PPP occurs in what cell compartment?

Cytosol

Two phases of PPP?

Oxidative and non-oxidative

Oxidative phase produces what?

NADPH

Non-oxidative phase produces what?

Sugar intermediates

Rate-limiting enzyme of PPP?

Glucose-6-phosphate dehydrogenase

First product after G6P in PPP?

6-phosphogluconolactone

Enzyme converting 6-phosphogluconolactone to 6-phosphogluconate?

Gluconolactonase

6-phosphogluconate dehydrogenase produces?

NADPH and CO₂

Immediate product before ribose-5-phosphate?

Ribulose-5-phosphate

Enzyme converting ribulose-5-phosphate to ribose-5-phosphate?

Isomerase

How many NADPH molecules produced per G6P?

2

Oxidative phase of PPP is?

Irreversible

Transketolase requires what cofactor?

TPP

Transaldolase transfers how many carbons?

3 carbons

Transketolase transfers how many carbons?

2 carbons

Non-oxidative phase links PPP with?

Glycolysis

PPP intermediates entering glycolysis?

F6P and G3P

Erythrose-4-phosphate is precursor for?

Aromatic amino acids

Xylulose-5-phosphate formed by?

Epimerase

Highest concentration of G6PD found in?

Phagocytes

NADPH oxidase uses NADPH to produce?

Superoxide

Superoxide generates what antimicrobial molecule?

Hydrogen peroxide

Liver P450 detoxification requires?

NADPH

NADPH maintains Hb iron in what state?

Ferrous (Fe²⁺)

NADPH deficiency can cause?

Methemoglobinemia

NADPH maintains what antioxidant in RBCs?

Reduced glutathione

Reduced glutathione scavenges?

ROS

Glutathione system requires what trace element?

Selenium

Maximum concentration of PPP occurs in?

Lens of eye

PPP helps maintain what in lens?

Transparency

Main importance of PPP in RBCs?

Protection from oxidative stress

Deficiency of G6PD predisposes RBCs to?

Oxidative damage

Ribose-5-phosphate is used for synthesis of?

Nucleotides

NADPH is used for synthesis of?

Fatty acids

NADPH cannot directly enter?

ETC

Main function of oxidative PPP phase?

NADPH generation

Main function of non-oxidative PPP phase?

Sugar interconversion

Anaerobic glycolysis converts pyruvate to?

Lactate

Purpose of lactate formation?

Regenerate NAD⁺

Pyruvate converted to acetyl-CoA produces?

NADH and CO₂

Glycolysis net ATP production?

2 ATP

Glycolysis occurs in?

Cytosol

Final product of aerobic glycolysis?

Pyruvate

Final product of anaerobic glycolysis?

Lactate