In: Biology
Nutritional biochemistry: The disease beriberi, which results from a dietary deficiency of vitamin B1 (thiamine, which leads to TPP), is characterized by neurologic and cardiac symptoms, as well as increased levels of pyruvate and -ketoglutarate in the blood. What specific complexes are affected by this lack of coenzymes, what metabolic pathways are affected, and what is the overall effect on aerobic metabolism?
Thiamine pyrophosphate (TPP) acts as a coenzyme in the many enzyme complexes. These complexes are-
a) Pyruvate dehydrogenase complex for the conversion of pyruvate to acetyl CoA during glucose metabolism or aerobic metabolism.
b) Pyruvate decarboxylase in ethanol fermentation.
c) Alpha-ketoglutarate dehydrogenase complex for the conversion
of alpha keto glutarate to succinyl coA.
d) Branched-chain amino acid dehydrogenase complex for catabolism
of branched chain Ami no acids like leucine, isoleucine.
Since TPP is important in the function of two important aerobic metabolism reactions-
Pyruvate to acetyl CoA conversion via pyruvate dehydrogenase. Lack of TPP will lead to accumulation of pyruvate without generating acetyl CoA.
Alpha keto glutarate to succinyl coA conversion via alpha keto glutarate dehydrogenase. This will lead to accumulation of alpha keto glutarate.
Overall these two reactions also release carbon dioxide which will not get released due to lack of coenzyme TPP. Also low amounts of TPP pushes much of the pyruvate to the lactate pathway which can lead to acidosis.