Table 1.

Nomenclatures of the proximal cluster

Generic designation	PC3	PC2	PC1
Core oxidation level	[4Fe-3S]5+	[4Fe-3S]4+	[4Fe-3S]3+
Equivalent oxidation level in conventional [4Fe-4S] core	[4Fe-4S]3+	[4Fe-4S]2+	[4Fe-4S]+
Cluster charge with all S-bonds	[4Fe-3S-6SCys]-	[4Fe-3S-6SCys]2-	[4Fe-3S-6SCys]3-
Calculated models in this study		PC2-	N/A
Glu76 charge	0 −1* −1	−1*	N/A
Cys20 N charge	−1 −1 −1	0	N/A
Overall PC charge	−2 −2 −3	−2	N/A

^*Distal Glu76 is not included in the overall PC charge count.