Explain lyases
These enzymes (code EC 4) cleave C-C, C-O, C-N and other bonds by elimination, forming double bonds or conversely adding groups to double bonds. Common names include decarboxylase, aldolase, dehydratase (if water is eliminated) or hydro-lyase (if the reverse reaction is more important or the only one which can be demonstrated). Spthase, but not synthetase, may be used as in tryptophan synthase or cystathionine P-synthase.