Figure 4. Ber e 1 copper interaction.

a) Paramagnetic copper relaxation enhancement experiment on Ber e 1. The spectrum shown in black is recorded in the absence of copper, whereas the spectrum shown in red has copper added in a 1∶1 (Cu²⁺:Ber e 1) stoichiometry. N-H groups in the backbone affected by paramagnetic relaxation enhancement by the addition of Cu²⁺ in a 1∶1 ration are HIS 20, CYS 21, ARG 22, TYR 24, GLU 43, HIS 45, SER 47, GLU 48, CYS 49, and GLN 52. In addition N-H groups form sidechains (s.c) of GLN 11, 13, 28 and 83 are also affected by Cu²⁺ at this stoichiometric ratio. b) A model of the copper atom positioning in Ber e 1, based on the nearby residues identified in (a). The N-H backbone groups that are bleached are indicated in the structure as orange rods. c) Due to the slow dynamics around the copper binding site, the copper atom is engulfed into the core of the protein. Interestingly, its position is very close to the bottom of the hydrophobic cavity.