| Popis: |
The double mutant H117G/N42C azurin exhibits tetragonal type 2 copper site characteristics with Cys42 as one of the copper ligands as concluded from spectroscopic evidence (UV-visible, EPR, and resonance Raman). Analysis of the kinetics of copper uptake by the apoprotein by means of stopped flow spectroscopy suggests that the solvent-exposed Cys42assists in binding the metal ion and carrying it over to the active site where it becomes coordinated by, among others, a second cysteine, Cys112. A structure is proposed in which the loop from residue 36 to 47 has rearranged to form a tetragonal type 2 copper site with Cys42 as one of the ligands. The process of copper uptake as observed for the double mutant may be relevant for a better understanding of the way copper chaperones accept and transfer metal ions in the living cell. |
