Concept explainers
Interpretation:
The pentose phosphate pathway for degrading sugars (see Problem 29-21) is the conversion of ribose 5-phosphate to glyceraldehyde 3-phosphate.
Concept introduction:
Reactions that make and break C-C-Bonds
Reactions that make and break carbon-carbon bonds form the basis of both degradative and biosynthetic
The breakdown of glucose to CO2 involves give such cleavages where as its synthesis involves the reverse process such reactions, considered from the synthetic direction involve addition of a nucleophilic carbanion to an electrophilic carbon atom. The most common electrophilic carbon atoms in such reactions are the sp2 hybridized carbonyl atoms of
Stabilized carbanions must be generated to add to these electrophilic centres. Three examples are the aldol condensation (catalyzed eg by aldolase) claisen ester condensation (citrate synthase) and the decarboxylation of β-keto acids. (isocitrate dehydrogenase and fatly acid synthase).
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Organic Chemistry
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