Shikimate pathway

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Chorismate pathway 1

Chorismate pathway 2

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Prephenate biosynthesis

Tyrosine biosynthesis

Shikimate Pathway is a seven-step metabolic route used by bacteria, fungi, algae, plants, and some parasitic organisms, but it is absent in animals. This pathway is crucial for the biosynthesis of aromatic amino acids: phenylalanine, tyrosine, and tryptophan, which are essential for the production of proteins and other important molecules necessary for the organism's survival. The shikimate pathway is named after the shikimic acid, an intermediate compound in the pathway.

Overview

The shikimate pathway begins with the condensation of phosphoenolpyruvate (PEP) and erythrose-4-phosphate (E4P) and progresses through several biochemical transformations involving different enzymes to produce chorismate, a precursor to the aromatic amino acids. The pathway is tightly regulated to ensure the proper production of these essential compounds without excess.

Importance

The importance of the shikimate pathway lies not only in the synthesis of the aromatic amino acids but also in the production of many other biologically significant secondary metabolites, including vitamins (such as folate), alkaloids, and flavonoids, which play roles in plant defense mechanisms and have various pharmaceutical properties.

Inhibition and Herbicides

The shikimate pathway is the target of the widely used herbicide glyphosate, which inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase. This inhibition blocks the pathway, leading to the depletion of essential aromatic amino acids in plants, ultimately causing plant death. The specificity of glyphosate to the shikimate pathway in plants and microorganisms, and its absence in animals, makes it an effective and relatively safe herbicide.

Research and Medical Implications

Research into the shikimate pathway has implications for both agriculture and medicine. Understanding the pathway can lead to the development of new herbicides and antibiotics by targeting specific enzymes within the pathway. Additionally, since the shikimate pathway is absent in humans, it represents a potential target for developing treatments against microbial infections without affecting human cells.

Conclusion

The shikimate pathway is a fundamental metabolic route with significant implications for biology, agriculture, and medicine. Its study helps in understanding the complex biochemical processes of life and in the development of new technologies and treatments for human benefit.