poliketidek

Poliketides are a large and structurally diverse class of natural products produced by bacteria, fungi, and plants. They are characterized by a polyketide backbone, which is a long chain of repeating two-carbon units derived from acetyl-CoA and malonyl-CoA during biosynthesis. This backbone is then often modified through various enzymatic processes, including cyclization, oxidation, reduction, and glycosylation, leading to a wide array of complex structures.

The biological activities of poliketides are equally varied. Many are known for their potent pharmacological properties, making them important sources for drug discovery. Examples include antibiotics like erythromycin and rapamycin (also known as sirolimus), antifungals such as amphotericin B, and immunosuppressants like tacrolimus. Some poliketides also function as herbicides, insecticides, or toxins.

The biosynthesis of poliketides occurs through the action of large multi-enzyme complexes called polyketide synthases (PKSs). These PKSs assemble the polyketide chain in a modular fashion, with each module catalyzing specific steps in the elongation and modification process. The genetic organization of PKS genes often reflects the structure of the resulting poliketide, allowing for a degree of predictability in understanding their biosynthetic pathways. Research into poliketides continues to be an active area, driven by the search for new therapeutic agents and a deeper understanding of natural product biosynthesis.