The Β-oxidation is the set of processes that take place on carbon in Β carbonyl.
The first enzyme in the process is acyl coenzyme A dehydrogenase which is found on the inner mitochondrial membrane and has as a cofactor the FAD which is reduced to FADH2 and cedes its reducing power to coenzyme Q (respiratory chain); this enzyme catalyzes the reaction that from an acyl coenzyme A, leads to the formation of enzyme coenzyme A (more precisely the trans 2.3 enoyl coenzyme A) which is an α-Β unsaturated system (alkene). The second enzyme of b-oxidation is enoyl coenzyme A hydratase which converts the enoil into L-Β hydroxy acyl coenzyme A; this enzyme is absolutely stereospecific for the L-Β hydroxy acyl coenzyme A isomer.
The next reaction is catalyzed by L-Β hydroxy acyl coenzyme A dehydrogenase (NAD dependent enzyme) which converts L-ossi hydroxy acyl coenzyme A into b-keto acyl coenzyme A; at the same time the reduction of NAD + takes place at NADH.
Finally, a thiolase (b-keto acyl coenzyme A thiolase) intervenes; the reaction also requires a lytic agent represented by coenzyme A: a fragment with two carbon atoms is formed (ie acetyl coenzyme A) and the remaining carbon skeleton represents an acyl coenzyme A (compared to the starting one it has lost two atoms of carbon).
The acyl coenzyme A obtained with ossid- oxidation, repeats the process until only acetyl coenzyme A is obtained.
Almost absolute rule: when dehydrogenation occurs between two adjacent atoms with a clear difference in electron affinity, the cofactor of the enzyme dehydrogenase, is almost always the NAD, whereas, if dehydrogenation occurs between two adjacent atoms between which there is little difference of electronic affinity, the cofactor is the FAD.
