THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE |
| |
| Authors: | R B Ramsey J P Jones H J Nicholas |
| |
| Institution: | Institute of Medical Education and Research and Department of Biochemistry, St. Louis University School of Medicine, St. Louis, Missouri 63104 |
| |
| Abstract: | Abstract— The distribution of 14C into several subcellular fractions of adult rat brain was studied as a function of time, following intracerebral injection of 2-14C]mevalonic acid. As expected from previous studies, the microsomal fraction was indicated as the site of sterol biosynthesis. The myelin fraction showed a marked and early uptake of I4C-labelled, digitonin-precipitable material. This was assumed to be a non-enzymic uptake of sterol intermediates. The mitochondrial fraction exhibited a rapid uptake of 14C-labelled, nonsaponifiable material, but a very slow accumulation of 14C-labelled, digitonin-precipitable product. Examination of the nonsaponifiable 14C-fractions by TLC showed a rapid appearance of labelled 4-desmethyl sterols in the microsomal fraction. The myelin fraction selectively retained 4,4'-dimethyl sterol but seemed to release this with time, possibly to be further metabolized by the microsomes. Examination of 14C]digitonin-precipitable material by the dibromide method showed that although labelled 4-desmethyl sterol appeared quite early, cholesterol itself was formed slowly in all fractions. |
| |
| Keywords: | |
|
|
