| Abstract: | Some peculiarities of ubiquinone (Q) biosynthesis in the livers of vitamin E-deficient rats induced in vitro by alpha-tocopherol and S-adenosylmethionine (SAM) were investigated. When C3H3]SAM was used as a precursor, alpha-tocopherol added to the sample induced a marked elevation of the content of Q concomitantly with a drastic increase (2.82-fold) of specific radioactivity of Q in the liver as compared to control. Under identical conditions with 2-14C sodium acetate as precursor, exogenous alpha-tocopherol increased the content (by 31.4%) and specific radioactivity (by 65.2%) of Q in experimental samples, whereas the corresponding parameters of ubichromenol (QC) were essentially unchanged. SAM added to the incubation medium caused a marked increase in the content and specific radioactivity of both Q and QC as compared to control. Similar, and even more conspicuous changes were observed after combined administration of alpha-tocopherol and SAM. The role of vitamin E in the activation of methylation reactions at terminal steps of Q and QC biosynthesis in rat liver is discussed. |
