REDOX CHEMISTRY &BIOCHEMISTRY OF ORGANOSULFUR COMPOUNDS

An understanding of biological oxidations is fundamental to an
understanding of heart functions. The energy produced in biological
oxidations is used to drive the synthesis of adenosine triphosphate (ATP),
which is the major energy source for heart muscle contraction and active
ion transport. The objective of this research is to discern the
significance of sulfur chemistry in biological oxidation. The oxidation of divalent sulfides is surprisingly facile in the presence
of suitable neighboring groups, such as those commonly found in proteins.
Neighboring group interaction depends markedly on geometry. Simple rigid
systems are studied to discern the basis for the interactions. A series of
physical organic, electrochemical, spectroscopic (IR, UV, ESR and PE),
X-ray crystallographic and pulse radiolysis techniques are used to study
electron deficient sulfide intermediates. A sulfur atom is ligated to the
iron atom of cytochrome c and analogues. The significance of the
iron-sulfur interaction will be studied. The combination of neighboring
group interactions between the ligated sulfur atom and the proximate side
chains of other amino acids and heme iron-sulfur interactions may be the
key to understanding the redox properties of these cytochromes. Our work on the chemistry of electron deficient sulfides also offers the
opportunity to discern the mechanism and significance of the reaction of
hydroxyl radicals with methional. Hydroxyl radicals are very important
intermediates in biological oxidations and methional has been widely used
as a specific probe for these radicals in enzymic systems.