Which among the following controls is an allosteric inhibitor of TCA cyclea) Pyruvate dehydrogenaseb) Ketoglutarate dehydrogenasec) Isocitrate dehydrogenased) Malate dehydrogenase
Pyruvate dehydrogenase; 'h' i.e., Ketoglutarate dehydrogenase & 'c' i.e., Isocitrate dehydrogenase 

Allosteric modulation in TCA cycle :- Citrate synthase, a-ketoglutarate dehydrogenase, Isocitrate dehydrogenase.
Both allosteric and covalent modulation:- PDH complex.
"Citrate synthase, isocitrate dehydrogenase and a-ketoglutarate dehydrogenase are allosteric enzymes which regulate TCA cycle".
a
b
bcd
abc