Ubiquinone biosynthesis in rat liver peroxisomes.
The possibility that ubiquinone biosynthesis is present in rat liver peroxisomes was investigated. The specific activity of trans-prenyltransferase was 30% that of microsomes, with a pH optimum of around 8. trans-Geranyl pyrophosphate was required as a substrate and maximum activity was achieved with Mn(2+). Several detergents specifically inactivated the peroxisomal enzyme. The peroxisomal transferase is present in the luminal soluble contents, in contrast to the microsomal enzyme which is a membrane component. The treatment of rats with a number of drugs has demonstrated that the activities in the two organelles are subjected to separate regulation. Nonaprenyl-4-hydroxybenzoate transferase has about the same specific activity in peroxisomes as in microsomes and like the transferase activity, its regulation differs from the microsomal enzyme. The results demonstrate that peroxisomes are involved in ubiquinone biosynthesis, and at least two enzymes of the biosynthetic sequence are present in this organelle.
Tekle
Michael
M
Department of Microbiology, Pathology and Immunology, Division of Pathology, Huddinge University Hospital, Karolinska Institutet, SE-141 86 Stockholm, Sweden. michael.tekle@impi.ki.se
Bentinger
Magnus
M
Nordman
Tomas
T
Appelkvist
Eeva-Liisa
EL
Chojnacki
Tadeusz
T
Olsson
Jerker M
JM
D000818:Animals; D002413:Cations, Divalent; D003902:Detergents / Q000494:pharmacology; D004122:Dimethylallyltranstransferase / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013379:Substrate Specificity; D014451:Ubiquinone / Q000096:biosynthesis*
D002413:Cations, Divalent; D003902:Detergents; D014451:Ubiquinone; D004122:Dimethylallyltranstransferase