Lanosterol, biosynthesis structure

The biosynthesis of these antibiotics has attracted interest because of their protolanosterol structure. Thus, fusidic acid was shown to incorporate [2- " C]-and (47 )-[2- " C,4- H]mevalonic acid (5.151) as well as squalene in accordance with a pathway in which the final backbone rearrangement of lanosterol biosynthesis has not taken place. 

The most recent mechanistic studies of lanosterol biosynthesis, which have been conducted with purified enzyme from recombinant sources, have revealed that the cyclization involves discrete carbocations during C-ring formation and specifically that a five-membered C-ring cationic structure 58 is first... 

The most abundant member of the steroid family in animals is cholesterol, the precursor of all other steroids. Cholesterol is an important component of cell membranes its ring structure causes it to be more rigid than other membrane lipids. In the biosynthesis of cholesterol, squalene is converted to lanosterol, which is converted to cholesterol. 

Despite their relative simplicity in chemical structure, steroid metabolism is important for the regulation of their cellular and physiological actions. Steroid metabolism involves in three main levels (1) steroid biosynthesis (from simpler precursors to steroids lanosterol and cycloartenol), (2) steroidogenesis (the metabolic interconversion among diverse steroids), and (3) steroid degradation. 

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