isoprénoïdes

Isoprenoids, also known as terpenoids, are a large and diverse class of organic chemicals that are produced by many living organisms, including plants, animals, and microorganisms. They are derived from five-carbon isoprene units and are often involved in various biological processes. Isoprenoids are classified based on the number of isoprene units they contain, ranging from hemiterpenes (one isoprene unit) to polyterpenes (many isoprene units).

The biosynthesis of isoprenoids occurs through two main pathways: the mevalonate pathway and the methylerythritol phosphate pathway. These pathways produce isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), which are the building blocks for all isoprenoids. The assembly of these building blocks is catalyzed by various enzymes, leading to the formation of different isoprenoid structures.

Isoprenoids play crucial roles in many biological functions. In plants, they are involved in processes such as photosynthesis, growth regulation, and defense mechanisms. Some isoprenoids, like carotenoids, act as pigments that protect plants from excessive light and attract pollinators. In animals, isoprenoids are involved in processes like cholesterol biosynthesis, which is essential for membrane structure and function. Additionally, some isoprenoids have important pharmacological properties and are used in the production of drugs, fragrances, and flavors.

The diversity of isoprenoids is vast, with over 55,000 known structures. This diversity arises from the various combinations and modifications of the isoprene units, as well as the different enzymes involved in their biosynthesis. The study of isoprenoids continues to be an active area of research, with potential applications in medicine, agriculture, and biotechnology.