active carbon dioxide

ac·tive car·bon di·ox·ide

, activated carbon dioxide

complex of N-carboxybiotin (biotin + CO₂) and an enzyme; the form in which carbon dioxide is added to other molecules in carboxylations, for example, to methylcrotonyl-CoA to form β-methylglutaconyl in the catabolism of leucine, and to acetyl-CoA to form malonyl-CoA.
See also: acetyl-CoA carboxylase.