The reaction shown is a key step in tryptophan bio synthesis.

(b) provide a mechanism, using curved-arrow notation, for the fragmentation
reaction shown above. the x-ray crystal structure of the enzyme that catalyzes this
reaction reveals that a glutamate residue is suitably positioned to serve as a general
acid-general base, and an aspartate residue serves as an electrostatic catalyst. indicate the roles of these residues in you catalytic mechanism.