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leucine |
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leucine (l `sēn), organic compund, one of the 20 amino acids amino acid (əmē`nō)..... Click the link for more information. commonly found in animal proteins. Only the l-stereooisomer appears in mammalian protein. It is one of several essential amino acids needed in the diet; the human body cannot synthesize it from simpler metabolites. Young adults need about 31 mg of this amino acid per day per kilogram (14 mg per lb) of body weight. Leucine can be degraded into simpler compounds by the enzymes of the body. Leucine contributes to the structure of proteins into which it has been incorporated by the tendency of its side chain to participate in hydrophobic interactions. Certain proteins that bind to DNA (see nucleic acid nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis. ..... Click the link for more information. ) and may help regulate its activities, posses regions in which leucines are arranged in configurations called leucine zippers. Leucine was isolated from cheese in an impure form in 1819 and from muscle and wool in the crystalline state in 1820. It was named after the Greek word leukos [white], evidently because at that time the purification of a subtance from nature to a white, crystalline state was considered noteworthy. The stucture of leucine was established by laboratory synthesis in 1891. See isoleucine isoleucine (ī'səl leucineOne of the essential amino acids, present in most common proteins and particularly abundant in hemoglobin. One of the first amino acids discovered (1819), it is used in biochemical research and as a nutritional supplement. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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8, were incubated overnight at 37[degrees]C with pronase (Calbiochem, EMD Biosciences, San Diego, CA) at 1:100 wt/wt ratio and leucine aminopeptidase (Sigma-Aldrich) at 1:1,000 wt/wt ratio. By an enzyme-histochemical method, leucine aminopeptidase reactivity was localized principally within the cytoplasm of granulated cells in the buccal cavity, esophagus, esophageal pouch, hepatopancreas, and the third intestinal region, which implies that these sites are responsible for the synthesis and secretion of this peptidase for the digestion of proteinaceous nutrients. Additional isoenzyme markers are currently being sought, including leucine aminopeptidase (LAP), which has been resolved with the same buffers as MDH. |
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