Iron-sulfur proteins categories

The many redox reactions that take place within a cell make use of metalloproteins with a wide range of electron transfer potentials. To name just a few of their functions, these proteins play key roles in respiration, photosynthesis, and nitrogen fixation. Some of them simply shuttle electrons to or from enzymes that require electron transfer as part of their catalytic activity. In many other cases, a complex enzyme may incorporate its own electron transfer centers. There are three general categories of transition metal redox centers cytochromes, blue copper proteins, and iron-sulfur proteins. 

Nonheme iron proteins do not contain a heme group, as their name indicates. Many of the most important proteins in this category contain sulfur, as is the case with the iron-sulfur proteins that are components of the respiratory complexes. The iron is usually bound to cysteine or to (Figure 20.11). There... 

Another type of iron-containing monpoxygenase was flrst described by Bernhardt et al. ) and contains a two iron-two-acid-labile-sulfur cluster. It was isolated from bacteria and catalyzes the 0-demethylation of 4-methoxybenzoate The corresponding electron transport chain involves NADH, a flavoprotein and a second iron-sulfur protein It seems that many more bacterial monooxygenases belong to this type rather than to the heme-sulfur-containing category. 

---