Phenylalanine, electronic structure

Tyrosinase is a monooxygenase which catalyzes the incorporation of one oxygen atom from dioxygen into phenols and further oxidizes the catechols formed to o-quinones (oxidase action). A comparison of spectral (EPR, electronic absorption, CD, and resonance Raman) properties of oxy-tyrosinase and its derivatives with those of oxy-Hc establishes a close similarity of the active site structures in these proteins (26-29). Thus, it seems likely that there is a close relationship between the binding of dioxygen and the ability to "activate" it for reaction and incoiporation into organic substrates. Other important copper monooxygenases which are however of lesser relevance to the model studies discussed below include dopamine p-hydroxylase (16,30) and a recently described copper-dependent phenylalanine hydroxylase (31). 

Fig. 1. Stereodrawing of the molecular structure of /V-pheynlacetyl-L-phenylalanine drawn by ORTEPll (Johnson, 1967). Molecular mechanics and dynamics calculations of the compound both in vacuum and in the crystal environment reproduced the observed crystal structure only when the appropriate partial electronic charges were used for the aromatic carbon and hydrogen atoms.

---