<prompt> Intermediate metabolite in TCA cycle are AEPyruvateIsocitrateOxaloacetateMalonate  <response>: Pyruvic acid is a key substance in phase-II metabolism. 1. Principally it is formed from oxidation of glucose glycolysis by EM Pathway. Conversion of PA to OAA by CO2-Fixation Reaction Pyruvic acid can be conveed to oxaloacetate by the enzyme Pyruvate carboxylase. The enzyme requires: Biotin as a prosthetic group which brings CO2 ATP and Mg Requires acetyl-CoA Acetyl-CoA does not enter into the reaction but may by combination with the enzyme maintains it in active conformation ve modifier. The generation of acetyl-CoA in metabolic reactions activates the enzyme and promote the formation of oxaloacetic acid OAA required for oxidation of acetyl-CoA in the TCA Cycle. Anaplerotic Reactions A sudden influx of Pyruvic acid PA or of acetyl-CoA to the TCA cycle might seriously deplete the supplies of OAA required for the citrate synthase reaction. Two reactions that are auxiliary to the TCA cycle operate to prevent this situation. These are known as anaplerotic Filling up reactions.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 334 