Did you have a look to : http://string.embl.de ?
There's a lot of interaction type referenced in this database.
For specific metabolic pathways, Kegg database is the
reference:http://www.genome.ad.jp/kegg/
Sebastien
I am not a specialist in pathways, but you can check the sources mentioned
here: http://www.biopax.org/ or try www.wikipathways.org maybe.
Ciao
Michaela
--
Time is the best teacher, but unfortunately, it kills all of its students.
- Robin Williams