After activation by ATP, once inside the mitochondria, the β-oxidation of a fatty acids occurs via four recurring steps:
#Oxidation by FAD
#Hydration
#Oxidation by NAD
# Thiolysis
# Production of acyl-CoA and acetyl-CoA
The final product of β-oxidation of an even-numbered fatty acid is acetyl-CoA, the entry molecule for the citric acid cycle. If the fatty acid is an odd-numbered chain, the final product of β-oxidation will be propionyl-CoA. This propionyl-CoA will be converted into intermediate methylmalonyl-CoA and eventually succinyl-CoA, which also enters the TCA cycle.