Seeing peroxisomes

Seeing peroxisomes t about the same time that Christian de Duve and his colleagues were describing the biochemistry of lysosomes (see “Catching sight of lysosomes” JCB 168: 174), they biochemically identified (Baudhuin et al., 1965) and purified (Leighton et al., 1968) another enzyme-containing organelle. Initially the organelle was known as the microbody, and de Duve declined to give it a more specific name in 1965 because “too little is known of their enzyme complement and of their role in the physiology of the liver cells to substantiate a proposal at the present time” (Baudhuin et al., 1965). But in an abstract presented at the 1965 American Society for Cell Biology annual meeting and a year later in print (de Duve and Baudhuin, 1966), de Duve proposed that the new organelle be called a peroxisome, because it appeared to both generate and break down hydrogen peroxide. A Swedish graduate student, J. Rhodin, had first described microbodies in his dissertation in 1954, after spotting their distinctive morphology. A year later, they were described in a paper that mistakenly suggested, based on appearance and location, that they were precursors to mitochondria (Rouiller and Bernhard, 1956). Subsequently other researchers observed similar structures by microscopy “but no one knew the function of these particles,” says de Duve. “There were all kinds of wild speculations about what they might do.” de Duve’s group modified a cell fractionation method devised by Robert Wattiaux and colleagues for separating peroxisomes, lysosomes, and mitochondria, which required injecting animals with Triton WR-1339 (Wattiaux et al., 1963). “The compound accumulates in lysosomes and causes them to float in a sucrose gradient,” says de Duve. This technique led to a full identification of peroxisomes using microscopy and biochemistry (Baudhuin et al., 1965), when they were clearly shown not to be related to mitochondria. In a landmark paper published in JCB in 1968 (Leighton et al., 1968), de Duve described the first large-scale preparation of peroxisomes—a feat that made possible more conclusive and precise characterization of their biochemical and morphological properties. “The same technique was to be used for many years to come in the study of the biogenesis of peroxisomes,” says de Duve. A Peroxisomes are almost the only component present after purification. D D U VE Text by Laura Bonetta