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Wednesday, February 11, 2009

Nobel Laureate: Christian de Duve


The Nobel Prize in Physiology or Medicine 1974

"for their discoveries concerning the structural and functional organization of the cell"

Christian de Duve (1917 - ) won the Noble Prize in 1974 for discovering lysosomes and peroxisomes. He shared the prize with two other cell biologists; Albert Claude and George Palade.

Here's the Press Release.

Nobel Laureates
Whereas Palade is in the first hand the morphologist searching the chemical correlate of the structures he has observed Christian de Duve is the biochemist who through his work can make predictions about new structural entities. Also the work of de Duve was a direct consequence of Claude's contributions in the area of chemical fractionation of cell components. de Duve started his work using differential centrifugation and he looked for the distribution of different enzymes among the four fractions resulting from Claude's procedure. These were nuclei, mitochondria (energy producers of the cell), microsomes (fragmented endoplasmic reticulum) and cell sap. He then found that certain enzymes sedimented such that they could not belong to any of the known morphological components. He discovered that they would sediment with a special class of particles, a fifth fraction. Interestingly all the enzymes were of a kind attacking protoplasmic components and de Duve therefore postulated that they had to be confined to membrane limited particles in order not to damage the cell. In accordance with this he found that agents dissolving membranes liberated the enzymes. It was soon possible for de Duve in collaboration with electron microscopists to make a morphological identification of the isolated components which were named lysosomes.

Lysosomes have now been shown, by de Duve and others, to be engaged in a series of cellular activities during which biological material must be degraded. The lysosomes are used in defense mechanisms, against bacteria, during resorption and secretion. They can also be used for a controlled degradation of the cell in which they are contained, e.g. to remove worn out components. Normally the cell is protected from the aggressive enzymes by protecting membranes but during certain conditions the lysosomal membranes may break down and the lysosomes are then real suicide pills for the cell. In medicine the lysosomes are of interest in many areas. There are a number of hereditary diseases with lysosomal enzyme deficiencies. This leads to accumulation of undigestible material in the lysosomes which swell and engorge the cell so as to prevent its proper functioning.

de Duve has not only a highly dominating role in lysosome research, he is also the discoverer of another cell component, the peroxisome, the function of which is still enigmatic but which may very well offer a story as fascinating as that of the lysosomes in the future.

The images of the Nobel Prize medals are registered trademarks of the Nobel Foundation (© The Nobel Foundation). They are used here, with permission, for educational purposes only.

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