BCMB Case 10

Metabolon

supramolecular multienzyme complex that the enzymes of the citric acid are predicted to be organized into

* metabolons mediate substrate channeling of intermediate metabolites from one active site to the next

advantages of a metabolon

* by holding the enzymes and reactions close together, less substrates diffuse away. this maintains high substrate and enzyme concentration levels in one area. this allows for reactions to happen quicker since enzyme and substrates are more accessible.


* increasing local concentrations of the enzymes and their substrates, improving channeling of intermediates into specific sub-pathways and increasing metabolic fluxes and sequestration of reactive intermediates.

where are the citric acid cycle enzymes located?

the matrix of the mitochondria

glyoxylate cycle

plants/bacteria synthesize sugars from fatty acids (animals can’t do this). They bypass CO2 releasing reactions of the citric acid cycle.

* lacks reactions 3-5 of the citric acid cycle, causing the glyoxylate cycle to bypasss the reactions in which CO2 is lost during the citric acid cycle

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==The glyoxylate cycle takes 2 acetyl-CoAs and converts these into succinate (4 carbons) for conversion to oxaloacetate and gluconeogenesis.== (from powerpoint)

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\*\* two carbons are lost. there is no net accumulation of carbon into glucose

difference between TCA and glyxoylate cycle

the glyoxylate cycle is an ^^anabolic^^ pathway where glucose is produced from fatty acids while the TCA cycle is a ^^catabolic^^ pathway that produces a considerable amount of energy to cell

2 fates of acetyl-CoA in animal matabolism:

1. oxidation through the citrcic acid cycle
2. syntehsis of fatty acids

stage one of the citric acid cycle

many sources of carbon get funneled into the same central pathway

stage 2 of the citric acid cycle

the acetyl group on acetyl-CoA that started off as pyruvate is added to oxaolacetate to from strate

how much atp does the TCA produce

1 ATP

stage 3 of the citric acid cycle

the reduced electron carriers (NADH and FADH) are oxidized to synthesize more ATP

main product produced by the citric acid cycle

reduced electrons carriers that can be oxidized in the electron transport chain

which reaction in the TCA cycle is most similar to the PDH reaction

a-ketogluterate dehydrogenase complex

pyruvate dehydrogenase

catalyzes the conversion of pyruvate to acetyl-CoA

* connects the citric acid cycle and subsquent oxidative phosphorylation to the glycolysis, gluconeogenesis and lipid and amino acid metabolism pathways.

vitamin B1 and pryuvate

Without vitamin B1, pyruvate cannot be made to run in the TCA cycle. This will eventually keep the ETC from running and will result in a lack of ATP which can cause you to get sick