METABOLIC AND ISOTOPIC CORRELATIONS BETWEEN D-GLUCOSE, L-ASCORBIC-ACID AND L-TARTARIC ACID

L-Ascorbic acid in fruit juices is enriched in C-13 by 4.8 delta-units relative to its precursor glucose, and this enrichment is mainly loca ted in position C-1. On the other hand, biotechnologically produced L- ascorbic acid preserves the pattern as expected from glucose. In grape s L-tartaric acid is synthesized from glucose via L-ascorbic acid and it is one of its main products. It preserves C-atoms 1 to 4 from gluco se and the measured delta(13)C-value is identical to that calculated f rom this precursor. The findings are interpreted as overlapping influe nces of isotope discriminations after metabolic branching and relative turnover rates leading to isotopic balances. The results can also be used to distinguish between identical products by different synthetic processes.