S-Adenosyl-l-methionine–cycloartenol methyltransferase activity in cell-free systems from Trebouxia sp. and Scenedesmus obliquus

摘要

p1. Homogenates prepared from iTrebouxia/i sp. 213/3 and iScenedesmus obliquus/i exhibited iS/i-adenosyl-l-methionine–cycloartenol methyltransferase activity. 2. The products of the reaction, with cycloartenol as the substrate, were 24-methylenecycloartanol and cyclolaudenol. 3. Optimal enzyme activity was found in homogenates prepared at pH7.6 and the transmethylase was distributed between the supernatant and microsomal fractions of the iTrebouxia/i homogenate. 4. The relevance of these results is discussed in relation to Csub28/sub and Csub29/sub sterol production in the algae./p