pentose phosphate pathway Flashcards
other names for pentose phosphate pathway (PPP)
hexose monophosphate pathway
phosphogluconate pathway
pentose shunt
oxidative phase makes NADPH - 3 reactions:
1.
2.
3.
- glucose 6-Phosphate Dehydrogenase (glucose 6-P → lactone)
- Lactonase is a hydrolase (opens ring by adding water)
- 6-Phosphogluconate Dehydrogenase (resulting in ribulose 6-P)
glucose 6-phosphate dehydrogenase:
- ____ glucose 6-phosphate to form a ____
- reduces ____ to form ____
- ____ reaction
- oxidizes lactone
- NADP+ NADPH
- rate-limiting
lactonase:
is a ____ (opens the ring by adding ____ )
hydrolase water
6-phosphogluconate dehydrogenase:
- oxidative ____ of 6-phosphogluconate to form ____
- reduces ____ to form ____
- decarboxylation ribulose 5-phosphate
- NADP+ NADPH
oxidized forms of NADPH
NAD+
NADP+
reduced forms of NADPH
NADH
NADPH
NAD+ is the cofactor for most enzymes that act in the direction of substrate ____ ( ____ )
oxidation ( deydrogenases )
NADPH functions as a cofactor for ____ , enzymes that catalyze substrate ____
reductases
reduction
reduced metabolites – ( ____ ) –> oxidized metabolites
dehydrogenases (catabolism)
oxidized metabolites – ( ____ ) –> reduced metabolites
reductases (anabolism)
NADH (reduced) – ( ____ ) –> NAD+ (oxidized)
ETC and OXPHOS
NADP+ (oxidized) – ( ____ ) –> NADPH (reduced)
pentose phosphate pathway
ATP – ( ____ ) –> ADP
NAD+ kinase
NADP+ – ( ____ ) –> NAD+
mitochondrial energy-linked transhydrogenase
why do we need NADPH:
- synthesis of ____
- ____ power
- monomers (biosynthesis: fatty acid, cholesterol, neurotransmitter, nucleotide)
- reducing (detoxification- reduction of oxidized glutathione, cytochrome P450 monooxygenases)
tissues with active pentose phosphate pathways:
adrenal gland (steroid synthesis)
liver (fatty acid and cholesterol synthesis)
testes (steroid synthesis)
adipose tissue (fatty acid synthesis)
ovary (steriod synthesis)
mammary gland (fatty acid synthesis)
Red blood cells (maintenance of reduced glutathione)
NADPH is required to keep supply of ____
glutathione
glutathione is a tripeptide, consisting of ____ , ____ , ____
glutamate, cysteien, glycine
glutathione interacts with proteins (no enzyme needed), this is important because it can ____ or ____ disulfide bonds
create or destroy
glutathione can ____ peroxides
inactivate
reactive oxygen species:
- maintain the redox ____ of cells
- too much can ____ macromolecules
- homeostasis
- damage
regeneration of reduced glutathione uses
NADPH
glucose-6-phosphate-dehydrogenase deficiency 5 classes:
1.
2.
3.
4.
5.
- chronic hemolytic anemia
- acute hemolysis due to nomral levels of oxidant stress
- acute hemolysis due to high levels of oxidant stress
- normal function (60-90% activity)
- normal function (too much G6PD activty)
G6PD & Hemolytic Anemia:
RBCs are destroyed in ____/____ not months
Fe in heme must be ____ to bind O2
hours/weeks
reduced
most severe effect of G6PDD is ____ ____
neonatal jaundice
G6PD and neonatal jaundice:
blood is normal but liver cannot ____ bilirubin
when bilirubin enters the brain (kernicterus), deafness, cerebral palsy, or ____ can result
conjugate
death
G6PD:
- monomer =
- dimer =
- tetramer =
- inactive
- active
- active
in patients with Ataxia Telangiectasia, HSP27 is ____
usually HSP27 promotes G6PD ____
without an active HSP27, G6PD cannot dimerize, therefor it is ____
inactive
dimerization
inactive
G6PD regulation:
- activators:
- inhibitors:
- dimerization; transcription factors for antioxidant genes; cell cycle and synthesis activators; insulin
- phosphorylation; apoptosis-signaling proteins
____ activates G6PD
insulin
high external glucose concentration in the ____ cells results in decreased G6PD
pancreatic beta-islet
PPP outputs:
- NADPH
- Energy (ATP)
- Nucleotides:
- primary product NADPH (run full PPP)
- primary products: F-6-P and GA3P (runs into glycolysis)
- primary product: ribose-5-P (run nonoxidative phase in reverse) OR primary product: ribose-5-P and NADPH (run oxidative phase only)
