@GreyOwl
Yes, so aspartate transanimase is an enzyme found in the cytosol and the mitochondria of a cell. It taks the amino group from glutamate and gives it to oxaloacetate, this produces a-ketoglutarate and aspartate. This effectively maintains the TCA cycle by using amino acids without the use of acetyl-coA (which comes from glycolysis and lipolysis). In doing so you make half the amount of NADH and one third of the amount of CO2.
The lack of CO2 may explain patients with ME/CFS that feel much worse after eating, because the cells in your stomach that produce acid actually do so by combining the CO2 made from their mitochondria with H2O to produce H+ (the acid) and HCO3 (bicarbonate - alkaline). They pump the acid into your stomach and release the bicarbonate in your blood. Now if they only produce one-third of CO2 from each TCA cycle then it may be exhaustive.
The reason this enzyme may be upregulated is for the very fact that it reduces NADH production. The electron transport chain (ETC) is the source of reactive oxygen species (ROS) or oxidative stress and as this rises the ETC itself is down regulated in response. If the ETC proteins are down regulated then the mitochondria can't make ATP from H+ fast enough and there may be an inbuilt mechanism to purposefully stall the overproduction of NADH and H+ in mitochondria so that it doesn't acidify itself. More research needs to be done in this area though.
Sepsis and starvation both lead to this metabolic pathway through different avenues but the suggestion is that the chronic immune activation (whatever the cause) is exhausting the body of the body of cofactors, vitamins and minerals to serve immune cell proliferation. The immune system uses ROS to fight infection and the increased ROS may be the trigger.