Working out one sugar molecule helped earn a string of Nobel Prizes
Glucose is life's main fuel, made from water and carbon dioxide by plants and burned by every organism. Understanding it proved so central to chemistry and medicine that it earned Nobel Prizes for Emil Fischer in 1902, for Otto Meyerhof in 1922, for the Coris in 1947, and for Luis Leloir in 1970.
Glucose, formula C6H12O6, is the most abundant simple sugar. Plants and most algae build it through photosynthesis and chain it into cellulose, the most plentiful carbohydrate on Earth, or store it as starch; animals store it as glycogen and circulate it in the blood as blood sugar. All organisms use it to make ATP, the cell's energy currency. The name comes from the Greek for wine or must, itself from the word for sweet.
Its history runs through German laboratories. Andreas Marggraf first isolated it from raisins in 1747, and Johann Tobias Lowitz found it in grapes in 1792, recognising it as distinct from cane sugar. Jean-Baptiste Dumas coined the name glucose in 1838, while August Kekule suggested dextrose, from the Latin for right, because its solutions rotate polarised light rightward. Today dextrose tends to appear on food labels and in clinics, glucose in biology, but both mean the same molecule.
Fischer's work between 1891 and 1894 pinned down the three-dimensional configuration of every known sugar and predicted the possible isomers, providing the first firm confirmation of van 't Hoff's ideas about how carbon bonds are arranged in space. Later prizes followed the sugar through the body: Meyerhof for glucose metabolism, Arthur Harden and Hans von Euler-Chelpin in 1929 for sugar fermentation, Bernardo Houssay for the pituitary gland's role, and Carl and Gerty Cori for how glycogen forms from glucose.
In water, glucose rarely stays a straight chain. Its aldehyde end reacts with a hydroxyl group on the same molecule, snapping into a ring, and more than 99 percent of dissolved glucose exists as six-membered pyranose rings in two mirror-related orientations called alpha and beta. Only the natural D form is widespread; its mirror image, L-glucose, is made synthetically in small amounts. Glucose solutions, alone or with salt, appear on the World Health Organization's List of Essential Medicines.
Source: Glucose
