Cobalt binding to the Aa,Ab,B2
tetramer. (Upper) Spectrum of Co(II) bound to the
Aa,Ab,B2 tetramer. The
concentration of the peptides was 40 μM in tetramer (80 μM in
metal-binding sites). The extinction coefficient at 550 nm was 140
M−1⋅cm−1 (per tetramer).
(Lower) Titration of the
Aa,Ab,B2 tetramer with
CoCl2. The concentration of peptides
was 40 μM in tetramer (80 μM in metal-binding sites). The curve
saturates at between 80 and 100 μM, indicating that two cobalt ions
are bound per tetramer.