Iron-sulfur proteins: ancient structures, still full of surprises

This article is a survey of the properties and functions of Fe-S proteins under the following headings: sulfur and iron; iron-sulfur clusters: evolution of cofactor use; early observations: complex and extended clusters: sulfur exchange and core interconversions; synthesis and biosynthesis of Fe-S clusters: functions of Fe-S clusters: electron transfer, electron delocalization, spin states and magnetism, covalency of sulfur bonds: non-electron transfer functions of Fe-S clusters: substrate binding and catalysis, regulatory and sensing functions.