Steroid

The steroids set up a group of Lipide S drifting of triterpénoïdes (lipids with 30 carbon atoms), mainly the squalene. They are completely characterized by a core cyclopentanophenanthrenic hydrophobic (fig. 1) partially or hydrogenated. Usually, carbons C10, C13 are related to a group Méthyl - CH3 and C17 carbon has a group alkyl. By extension, the steroids also include the lipids whose core cyclopentanophenanthrenic was modified by scission of a connection and the addition or the délétion of a carbon.

Nomenclature and Classification

According to IUPAC, the steroids included all lipids having a core cyclopentanophenanthrenic or drifting of this one:

In this case, the term of “steroid” thus refers only to the hormones stéroïdiennes. This use which is also often retained in medicine. In a sporting context, “steroid” is usually employed to indicate the steroids anabolics.

Some examples of steroids that the Protéobactérie Methylococcus capsulatus and the Planctomycète Gemmata obscuriglobus had Enzyme S counterparts with the squalene monooxygenase and the oxydosqualene cyclase, two enzymes necessary initially for the synthesis of sterols starting from the Squalène. In addition, the presence of Lanostérol was highlighted in the bacteria Methylococcus capsulatus and Methylosphaera hansonii . This could be explained by a side transfer of Gène between an ancestor of these bacteria and cells eukaryotes or by a phenomenon of Endosymbiose
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