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.

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.