Online Encyclopedia

ASPARAGINE

Online Encyclopedia
Originally appearing in Volume V02, Page 765 of the 1911 Encyclopedia Britannica.
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ASPARAGINE, C4HsN203, a naturally occurring base, found in plants belonging to the natural orders Leguminosae and Cruciferae. It occurs in two optically active forms, namely, as laevo-asparagine and dextro-asparagine. Laevo-asparagine was isolated in 18os by L. N. Vauquelin. A. Piutti (Gazz. chim. Ital., 1887, 17, p. 126; 1888, 18, p. 457) synthesized the asparagines from the monomethyl ester of inactive aspartic acid by heating it with alcoholic ammonia. In this way a mixture of the two asparagines was obtained, which were separated by picking out the hemihedral crystals. HOOC•CH•NH2•CH2•COOC2H5+NH3 = C2H SOH +H000•CH• NH2•CH2•CONH2. Laevo-asparagine is slightly soluble in cold water and readily soluble in hot water. It crystallizes in prisms, containing one molecule of water of crystallization, the anhydrous form melting at 234–235° C. Nitrous acid converts it into malic acid, HOOC•CHOH•CHZ•COOH. It is laevo-rotatory in aqueous or in alkaline solution, and dextro-rotatory in acid solution (L. Pasteur, Ann.Chim. Phys., 1851 [21, 31, p. 67). Dextro-asparagine was first found in 1886 in the shoots of the vetch (Piutti). It forms rhombic crystals possessing a sweet taste. It is dextrorotatory in aqueous or alkaline solution, and laevo-rotatory in acid solution. Hydrolysis by means of acids or alkalis converts the asparagines into aspartic acid; whilst on heating with water in a sealed tube they are converted into ammonium aspartate. The constitution of the asparagines has been determined by A. Piutti (Gazz. chim. Ital., 1888, 18, p. 457).
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