CALCULATED IONIZATION-POTENTIALS DETERMINE THE OXIDATION OF VANILLIN PRECURSORS BY LIGNIN PEROXIDASE

In view of the biocatalytic production of vanillin, this research focu sed on the lignin peroxidase (LiP) catalysed oxidation of naturally oc curring phenolic derivatives: O-methyl ethers, O-acetyl esters, and O- glucosyl ethers. The ionisation potential (IP) of a series of model co mpounds was calculated and compared to their experimental conversion b y LiP, defining a relative IP threshold of approximately 9.0 eV. Based on this threshold value only the O-acetyl esters and glucosides of is oeugenol and coniferyl alcohol would be potential LiP substrates. Both O-acetyl eaters were tested and were shown to be converted to O-acety l vanillin in molar yields of 51.8 and 2.3%, respectively. (C) 1998 Fe deration of European Biochemical Societies.