Biotin is needed in

Biotin acts as co- enzymes for carboxylation reactions .Bioitin captures a molecule of CO2 which is attached to nitrogen of biotin molecule.Energy required for this reaction is provided by ATP.Tgen activated carboxyl group is transferred to the substrate.Biotin requiring CO2 Fixation reactions. Acetyl CoA + CO2 + ATP=Methyl malonyl CoA + ADP+ Pi This is the rate limiting reaction in fattyacid synthesis. Propionyl CoA + CO2 + ATP = Methyl malonyl CoA + ADP + Pi In oxidation of odd chain fatty acids. Pyruvate+ CO2 + ATP = Oxaloacetate + ADP + Pi Oxaloacetate acts as catalyst for TCA cycle and as enzyme in gluconeogenic pathway Reference: DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION page no 485 Co-enzyme Main reaction using the co -enzyme Group transferred Thiamine pyrophosphate(TPP) oxidativedecarcoxylation of alpha keto acids in BPG shunt Hydroxyethyl Pyridoxalphosphate(PLP) Transamination, decarcoxylation of amino acids Aminogroup Biotin fatty acid synthesis, TCA cycle carbondioxide Co- enzyme-A ( Co-A) TCAcycle, fatty acid synthesis,gluconeogenisis, activation of acetoacetate, detoxification Acylgroup Tetrahydrofolate (FH4) Transmethylation reactions where methyl group required for synthesis of choline , epinephrine , creatine. One carbon groups Adenosinetriphosphate(ATP) universal energy currwncy Phosphate