<prompt> The enzyme involved in the activation for fatty acids beta oxidation is?ThiophoraseThiokinaseThiolaseThioesterase  <response>: Fatty acids must first be conveed to an active intermediate before oxidation. This is the only step in the oxidation of a fatty acid that requires energy from ATP. In the presence of ATP and coenzyme A, the enzyme acyl-CoA synthetase thiokinase catalyzes the conversion of fatty acid or FFA to an active fatty acid or acyl-CoA, using one high-energy phosphate and forming AMP and PPi. The PPi is hydrolyzed by inorganic pyrophosphatase with the loss of a fuher high-energy phosphate, ensuring that the overall reaction goes to completion. Acyl-CoA synthetases are found in the endoplasmic reticulum, peroxisomes, and on the outer membrane of mitochondria. 