This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Thiamine deficiency causes decreased energyproduction because 
Select and explain. 
A. It is required for the process of transamination, B. It is co-factor in oxidative reduction, C. It is co-enzyme for transketolase in pentose phosphate pathway, D. It is co-enzyme for pyruvate dehydrogenase
D: It is co-enzyme for pyruvate dehydrogenase
Answer: D: It is co-enzyme for pyruvate dehydrogenase 
Explanation: It is co-enzyme for pyruvate dehydrogenase Thiamine has a central role in energy-yielding metabolism and especially the metabolism of carbohydrates. Thiamine diphosphate is the coenzyme for: A) 3 multi-enzyme complexes that catalyzes oxidative decarboxylation reactions. - pyruvate dehydrogenase complex (catalyzes oxidative decarboxylation of pyruvate to acetyl-CoA) - a-ketoglutarate dehydrogenase in the citric acid cycle and - branched chain keto-acid dehydrogenase involved in the metabolism of leucine, isoleucine and valise. B) Transketolase, in the pentose phosphate pathway. The oxidative decarboxylation of pyruvate and a-ketoglutarate play a key role in energy metabolism of most cells. In thiamine deficiency, the activity of these two dehydrogenase reactions is decreased,, resulting in a decreased production of ATP.