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2011-05DayanF1.jpgClick to Enlarge ImagePorphyrins are a group of ring-shaped molecules that are ubiquitous in biology, and are largely responsible for pigments in everything from chlorophyll in plants to hemoglobin in blood. Franck E. Dayan and Emilie A. Dayan explore how porphyrins are much more than mere color, but are the "master rings" at the center of producing energy, transporting oxygen and generally sustaining life. It is possible that an inherited problem in porphyrin synthesis caused the “madness” of King George III in England. Other porphyrin diseases lead to light sensitivity, the withering of fingers and lips, and gums that may tighten to reveal fanglike teeth with reddish hues—possibly the origin of vampire myths. However, such deficiencies have proven useful in plant control, where herbicides that mimic porphyrins can cause photobleaching of weeds. The authors provide an inside look at this one substance that is hardly a household name, but is central to our health and survival.

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