Squalene epoxidase and oxidosqualene lanosterol-cyclase activities in cholesterogenic and non-cholesterogenic tissues

Squalene epoxidase and oxidosqualene lanosterol-cyclase activities have been studied in normal mammalian cholesterogenic and non-cholesterogenic tissues. This paper describes the kinetic conditions of measurement of these two enzymatic acitivities and their results. Oxidosqualene lanosterol-cyclase is a widespread enzyme, present in all cholesterogenic and non-cholesterogenic tissues. However, the level of squalene epoxidase is very low in non-cholesterogenic tissues. However, the level of squalene epoxidase is very low in non-cholesterogenic tissues. The effects of subcellular fractionizing and of the physico-chemical state of squalene incubated in vitro on squalene epoxidase activity are discussed.