isopentenyl

Isopentenyl is a five-carbon hydrocarbon substituent derived from isoprene that is used in chemistry and biochemistry to describe a particular alkene-containing moiety attached to other molecules. The term denotes a branched, partially unsaturated group that can be linked to nucleosides, enzymes, or metabolites in various contexts.

In biological systems, isopentenyl units are central to terpenoid biosynthesis and related pathways. They are produced and interconverted in cells from isoprenoid precursors such as isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). Through the action of prenyltransferases, isopentenyl units can be sequentially assembled to form longer isoprenoid chains that serve as precursors for a wide range of natural products, including sterols, vitamins, and essential signaling molecules.

A notable example of an isopentenyl-containing biomolecule is N6-isopentenyladenosine (i6A), a modification found at position 37 of certain transfer RNAs. In this modification, an isopentenyl group is attached to the N6 position of adenosine. The i6A modification is present in tRNAs of archaea and some bacteria and eukaryotes and is thought to influence tRNA stability and codon–anticodon interactions during translation.

Other related compounds include isopentenyl derivatives such as isopentenyladenosine and various isopentenyl-containing phosphate or pyrophosphate intermediates, which play roles as intermediates or donors in broader mevalonate- or non-mevalonate pathway chemistry that underpins terpenoid biosynthesis.