Alpha-oxidation of phytanic acid is believed to take place entirely within peroxisomes. 
#Phytanic acid is first attached to CoA to form phytanoyl-CoA.
#Phytanoyl-CoA is oxidized by phytanoyl-CoA dioxygenase, in a process using Fe and O, to yield 2-hydroxyphytanoyl-CoA.
#2-hydroxyphytanoyl-CoA is cleaved by 2-hydroxyphytanoyl-CoA lyase in a TPP-dependent reaction to form pristanal and formyl-CoA (in turn later broken down into formate and eventually CO).
#Pristanal is oxidized by aldehyde dehydrogenase to form pristanic acid (which can then undergo beta-oxidation).
(Propionyl-CoA is released as a result of beta oxidation when the beta carbon is substituted)