The Chemical Biology of Carbon
Chapter 9: Heterocycles in Chemical Biology: II. Vitamins
Published:05 Apr 2023
Special Collection: 2023 ebook collectionSeries: Chemical Biology
The Chemical Biology of Carbon, The Royal Society of Chemistry, 2023, ch. 9, pp. 306-354.
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This chapter on biologic nitrogenous heterocycles deals exclusively with the coenzymatically active forms of vitamins. Seven of the eight B vitamins use heterocyclic chemistry, each one a separate ring system, to mediate chemical transformations at key nodal metabolic intersections. The heterocycles include single ring heterocycles: the thiazolium ion in thiamin-PP, the cationic pyridinium in NAD(P)+, and the pyridine aldehyde in pyridoxal-P. Bis-heterocyclic rings include biotin and folate coenzymes. Riboflavin offers a tricyclic isoalloxazine ring system and B12 a tetrapyrrolic framework. The ranges of chemistry enabled include carbanion, carbocation, and carbon radical intermediates, as well as hydride ion transfers.