The active-site structure of the Cu(II)-containing phenylalanine hydroxylase from Chromobacterium violaceum was studied by electron spin-echo spectroscopy. Fourier transformation of the stimulated electron spin-echo envelope for the copper protein revealed frequency components characteristic of copper-histidyl imidazole coordination. The observed nuclear quadrupole frequencies at 0.55, 1.0, and 1.55 MHz are slightly different from those observed for model Cu(II)-imidazole complexes, 0.68, 0.72, and 1.40 MHz, but can be observed in Cu(II) complexes with 2-methylimidazole. A method of analysis by spectral simulation is presented for the quantitation of the number of equatorial imidazoles coordinated to Cu(II). In phenylalanine hydroxylase, two are bound.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry