Table 1.

Observed differences in nesting for different cluster binding motifs of 16-mer peptides. The percentage of frames showing three-thiol [2Fe–2S] and [4Fe–4S] nest formation along 100 ns of constant volume and temperature MD trajectories for GGyGGGyGGyGGyGGW (y = U for FdM-16-U thioGly, C for FdM-16-C Cys, and J for FdM-16-J homoCys) peptides are shown. The first value for [4Fe–4S] nest corresponds to the per cent of peptide conformations that can accept a preformed [4Fe–4S] cluster. The second value in parentheses is the per cent of conformations where the peptide backbone does not transect through the plane defined by the three S(thiol) centres, as a measure for the ceiling of cluster nest formation.

binding motif	CxxxCxxCa	CxxxCxxxxxC	CxxxxxxCxxC	CxxCxxCb	cumulative CxxxCxxCxxC
y = U or Sly
[2Fe–2S]	31.2	28.9	15.0	37.2	112.3c
[4Fe–4S]	n.a (2.9)	n.a (1.5)	n.a (2.0)	n.a (1.1)	n.a (7.5)
y = C or Cys
[2Fe–2S]	21.3	10.8	23.1	15.0	70.2
[4Fe–4S]	0.1 (0.7)	n.a (0.1)	n.a (0.3)	n.a (0.3)	0.1 (1.4)
y = J or Hey
[2Fe–2S]	6.9	36.6	26.4	14.6	84.5
[4Fe–4S]	n.a (0.1)	n.a (0.3)	n.a (0.03)	n.a (0.0)	n.a (0.4)

^aRadical SAM cluster binding motif.

^bBacterial ferredoxin cluster binding motif.

^cThe frame percentage greater than 100% is due to the presence of four thiol groups in these peptides.