polyketidi

Polyketides are a large and structurally diverse class of naturally occurring organic compounds produced by prokaryotes, fungi, and plants. They are synthesized by polyketide synthases (PKSs), which are multi-enzyme complexes. The biosynthesis of polyketides begins with the condensation of simple acyl-CoA precursors, typically acetyl-CoA and malonyl-CoA, in a process analogous to fatty acid synthesis. However, unlike fatty acids, the polyketide pathway involves a series of iterative elongation and modification steps, including reduction, dehydration, and other enzymatic transformations, leading to a wide array of complex molecular architectures.

The structural diversity of polyketides results from variations in the number of extender units incorporated, the type of modifying enzymes involved, and the subsequent cyclization and functionalization reactions. This structural variability underlies their broad spectrum of biological activities. Many polyketides are recognized for their significant pharmacological properties, making them important targets in drug discovery. Examples include antibiotics like erythromycin and tetracycline, antifungals such as amphotericin B, anticancer agents like doxorubicin, and immunosuppressants like rapamycin. The study of polyketides is crucial for understanding microbial metabolism, developing new therapeutic agents, and exploring novel biochemical pathways.