Hahlbrock, K. et al. 1970

• Authors: Hahlbrock, K.; Zilg, H.; Grisebach, H.
• Title: Stereochemistry of the enzymatic cyclisation of 4,2',4'-trihydroxychalcone to 7,4'-dihydroxyflavanone by isomerases from mung bean seedlings.
• Location: Eur. J. Biochem. 15, 13-18 (1970).
• Abstract: 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 chalcone-flavanone isomerases isolated from mung bean seedlings (Phaseolus aureus Roxb.) leads to the (-)(2 S)-7,4'-dihydroxyflavanone.
  When 4,2',4'-(alpha-2H)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 2H2O with the unlabeled chalcone, deuterium is preferentially located in the axial positon at C-3 of the flavanone. The mechanistic implications of these results are discussed.