4-coumaroyl-coenzyme-a and hinokiresinol

The selective formation of E- or Z-isomers is an important process in natural product metabolism. We show that the subunit composition of an enzyme can alter the geometrical composition of the enzymatic products. Hinokiresinol synthase, purified from Asparagus officinalis cell cultures, is responsible for the conversion of (7E,7'E)-4-coumaryl 4-coumarate to (Z)-hinokiresinol, the first step in norlignan formation. The protein is most likely a heterodimer composed of two distinct subunits, which share identity with members of the phloem protein 2 gene superfamily. Interestingly, each recombinant subunit of hinokiresinol synthase expressed in Escherichia coli solely converted (7E,7'E)-4-coumaryl 4-coumarate to the unnatural (E)-hinokiresinol, the E-isomer of (Z)-hinokiresinol. By contrast, a mixture of recombinant subunits catalyzed the formation of (Z)-hinokiresinol from the same substrate.

Topics: Acyl Coenzyme A; Asparagus Plant; Cells, Cultured; Cloning, Molecular; Dimerization; DNA, Complementary; Escherichia coli; Gas Chromatography-Mass Spectrometry; Lignans; Mass Spectrometry; Models, Chemical; Molecular Sequence Data; Phenols; Phylogeny; Plant Lectins