pentose phosphate shunt or hexose monophosphate pathway this pathway consists of two parts:
DESCRIPTION
Ferchmin/GradStud/ 2014. Pentose phosphate pathway or shunt (PPP). 2) Oxidative and isomerization parts. 3) Regulation 4) Metabolic roles of PPP 5) Reduction of glutathione. In glycolysis there was no net oxidation/reduction only “reshuffling” of the redox state of the carbons. - PowerPoint PPT PresentationTRANSCRIPT
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PENTOSE PHOSPHATE SHUNT or HEXOSE MONOPHOSPHATE PATHWAY
This pathway consists of two parts:
1) Glucose-6-P undergoes two oxidations by NADP+, the second is an oxidative decarboxylation that forms a pentose-P.
2) The P-pentoses that are formed during the first part are transformed into glucose-6-P.
Ferchmin/GradStud/ 2014
1) Pentose phosphate pathway or shunt (PPP). 2) Oxidative and isomerization parts.3) Regulation4) Metabolic roles of PPP 5) Reduction of glutathione.
In glycolysis there was no net oxidation/reduction only “reshuffling” of the redox state of the carbons
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GPDH deficiency is relatively common in persons with roots from regions with endemic malaria.
In glycolysis followed by TCA (Kreb’s) cycle the first Cs to be converted to CO2 are # 3 and 4. In PPP is C #1.
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2) Nonoxidative steps of pentose phosphate shunt
Positive regulator of lipid synthesis
transketolase requires thiamine pyrophosphate (vitamin B1)
transketolase requires thiamine pyrophosphate (vitamin B1)
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GSSG is oxidized and GSH reduced glutathione which will be discussed in next page
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Glutathione synthesis is not ribosomal and glutathione is not directly encoded in DNA.Notice the unusual bonds between cysteine and glutamate.
Unusual “peptide” bond.
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Link between hexose monophosphate pathway and reduction of peroxides
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Glutathione peroxidase has selenocysteine a rare amino acid that contains selenium. The story of selenocysteine incorporation into proteins is unusual.
There are many antioxidants that neutralize the oxygen reactive species (ROS). Among them are: vitamins C and E and recently the tomato red pigment, lycopene. Lycopene, became notorious for reportedly preventing prostate cancer and retinal macula degeneration.
Proposed mechanism of glutathione peroxidase