CLUSTERS color characteristics

We can group animals into clusters according to how similar they are, comparing their key characteristics the more closely those characteristics match, the more similar are the two species. The choice of characteristics is inherently arbitrary, but we might include the number of legs, covered in fur or feathers, the speed of movement, size, color, carnivore/ vegetarian, and so on ... 

The 2Fe2S (S, acid-labile sulfur) ferredoxins have a redox active binuclear center, with each of the two iron atoms attached to the protein by two cysteinyl sulfur ligands and connected by two inorganic acid-labile sulfur ligands. At cty-ogenic temperatures these clusters are EPR detectable, with characteristic features in the vicinity of g = 1.94. Spinach ferredoxin has principal g values of 2.03, 1.96, and 1.88 and a broad absorbance spectrum with a weak maximum around 420 nm, giving these proteins a reddish brown color which bleaches on reduction. Ferredoxins are low potential electron carriers chloroplast ferredoxins function in photosynthetic electron transfer, but related proteins such as adrenal ferredoxin are involved in steroidogenic electron transfer in mitochondria in tissues which produce steroid hormones. 

Metal-catalyzed reduction of methylviologen metal clusters internal or external location of metal cluster in zeolite Characteristic blue color of the reduced viologen radicals makes it ea to locate dusters. 

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