Properties and partial purification of squalene synthase from cultured cells of dandelion

Squalene synthase (SQS) activity was detected in the microsomal fractions of suspension-cultured cells of dandelion (Taraxacum officinale), which produce cycloartane (involved in phytosterol biosynthesis) and other classes (e.g. oleanane and ursane) of triterpenoids. High SQS activity was detected at the late logarithmic growth stage of the culture. The activity was solubilized from the microsomes by the use of detergents (glycodeoxycholate and octylthioglucopyranoside), and chromatographed on triple-joint-columns composed of cation-exchange, anion-exchange and hydroxylapatite resins. Active fractions were further subjected to chromatography on hydroxylapatite and anion-exchange reins, followed by fast protein liquid chromatography (FPLC) on a gel-filtration column. About a 50-fold purification compared with the microsomal activity was achieved at the hydroxylapatite stage, and, although the recovery was poor, the activity was retained in the final FPLC fractions.