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In Vitro Metabolism of Mevalonic Acid in the Bovine Retina
Author(s) -
Fliesler Steven J.,
Schroepfer George J.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb12989.x
Subject(s) - squalene , mevalonic acid , chemistry , biochemistry , metabolism , chromatography , silicic acid , sterol , fatty acid , in vitro , biosynthesis , terpenoid , saponification , cholesterol , organic chemistry , enzyme
Bovine retinas were incubated with 3RS‐[5‐ 3 H]‐ mevalonic acid under conditions similar to those previously shown to support opsin biosynthesis in vitro. TLC of the total lipids indicated the formation of numerous radiolabeled components, including sterols, hydrocarbons, and “fatty acid‐like material.” The nonsaponifiable lipids were analyzed by TLC, GLC, and chromatography on columns of silicic acid‐Super Cel, silica gel G‐Super Cel‐silver nitrate, and alumina‐Super Cel‐silver nitrate. The major nonsaponifiable components had the Chromatographic properties of squalene and “methylated sterols” (i.e., C 30 , C 29 , and C 28 monohydroxy sterols). Cholesterol represented no more than 1% of the total radioactivity in the nonsaponifiable lipid fraction. The “fatty acid‐like material” was derivatized with diazomethane, and the resulting methyl esters were analyzed by GLC before and after catalytic hydrogenation. The radioactivity did not correspond to the normal fatty acids endogenous to the retina, but rather had the Chromatographic properties of C 15 and C 20 isoprenoid acids. These results obtained with intact retinas are consistent with our previous observations concerning mevalonic acid metabolism in cell‐free homogenates of bovine retinas.