Carboxylation is governed by

Coenzyme role of Biotin Play a role in gene expression, fatty acid synthesis, gluconeogenesis and serve as a CO2 carrier for Carboxylases enzymes and gene regulation by histone biotinylation. Coenzyme for ATP dependent Carboxylation reaction (Carbon Dioxide Fixation) Pyruvate Carboxylase (Pyruvate to Oxaloacetate) Propionyl CoA Carboxylase (Propionyl CoA to Methyl Malonyl CoA) Acetyl CoA Carboxylase (Acetyl CoA to Malonyl CoA) Methyl Crotonyl CoA Carboxylase ref DM Vasudevan 8th ed page 473