Open AccessStereochemistry of the Enzymatic Cyclisation of 4,2′,4′‐Trihydroxychalcone to 7,4′‐Dihydroxyflavanone by Isomerases from Mung Bean Seedlings
Author(s) -
Hahlbrock Klaus,
Zilg Harald,
Grisebach Hans
Publication year - 1970
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1970.tb00969.x
Subject(s) - flavanone , isomerase , chemistry , chalcone , phaseolus , stereochemistry , enzyme , isomerization , chalcone isomerase , chalcone synthase , biosynthesis , botany , biochemistry , flavonoid , biology , catalysis , antioxidant
The stereochemistry of the enzyme mediated chalcone‐flavanone isomerisation has been investigated. Cyclisation of 4,2′,4′‐trihydroxychalcone catalysed by either one of the two chalconeflavanone isomerases isolated from mung bean seedlings ( Phaseolus aureus Roxb. ) leads to the (–)(2 S)‐7,4′‐dihydroxyflavanone. When 4,2′,4′‐[α‐ 2 H]trihydroxychalcone is the substrate, deuterium is located preferentially in the equatorial position at C‐3 of the flavanone as was shown by nuclear magnetic resonance measurements. Conversely, when the cyclisation is carried out in 2 H 2 O with the unlabeled chalcone, deuterium is preferentially located in the axial position at C‐3 of the flavanone. The mechanistic implications of these results are discussed.