Topics of Special Interest Structure Numbering Conformation Configuration Classes Nomenclature Biosynthesis of Cholesterol Structure Cyclopentanoperhydrophenanthrene skeleton Natural steroids have two methyls Rings are labeled A, B, C and D. Numbering Numbering of each position essentially follows a uniform pattern except for the methyls. Cholesterol is an important member of the cholestane series of steroids. There are four rings in a steroid skeleton and hence there are three fusion points. When there are directed on the same side, it is called cis. The three fusion centers.
Classes Following are the classes of steroids based on the number of nuclear carbons.
Additional carbons that are not nuclear are not to be considered in classifying a steroid. Nomenclature Study the following examples for an understanding on how the steroids are named. Use the above information on numbering, classes and configuration to deduce the name. This is the rate limiting step in cholesterol biosynthesis. Cholesterol is the raw material for synthesis of all steroid hormones.