We then standardized the obtained mappings so that the mapped reaction SMILES can be used directly to detect duplicates. As a final post-processing step, we added the backward reactions for reversible reactions. BRENDA labels some reactions as reversible, some as irreversible and some as unknown. For reversible reaction, we directly added the backward reaction to our dataset and labeled it 'reversed'. For reactions with unknown reversibility, we queried whether reactions with the reverse reaction template existed in the same EC class. If so, the reverse reaction was added to the dataset and labeled 'reversed_suggested'. Altogether, we thus arrive at approximately 63k reactions (235k if protein + organism information is taken into account), yielding the largest atom mapped database of enzymatic reactions to date. If the EC class is disregarded, this boils down to 48k non-duplicate reactions.