Sulfur formation, biological factors

Biological factors play many roles in the cycling of sulfur minerals associated with fossil fuels. Sulfate reduction may lead to the solution of eva-porite sulfates while production of sulfide ions at various stages in the formation and degradation of fossil fuels may lead to deposition of sulfide minerals or elemental sulfur (see Chapter 6.2). 

This group of proteins is ubiquitous. Most of the iron-sulfur proteins transfer electrons at negative redox potentials, e.g. in the respiratory chain or in photosynthesis, but some possess enzymatic, sensing or regulatory activity and they can also be involved in stabilization of protein domain structures or in radical formation. The important role of the element combination iron and sulfur in biology derives from many factors including availability, solubility and reactivity. The role of the sulfur ligands has been reviewed recently. For more reviews of various EPR-related aspects the reader is referred to the earlier report in this series. 

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