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5.1.8: The Eight Essential Monosaccharides

  • Page ID
    413252
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    Objectives

    1. identify and draw the eight essential monosaccharides

    Eight monosaccharides are required for the proper functioning of human beings. Although they are typically supplied through a healthy diet, they can be biosynthesized if required. The eight monosaccharides are L-fucose, D-galactose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, D-glucose, D-mannose, N-acetyl-D-neuraminic acid, and D-xylose.

    D-Galactose, D-Glucose, and D-Mannose are commonly found aldohexoses:

    clipboard_eca1b46e861603087072b1af01964529b.png

    D-Xylose is a common aldopentose.

    25.4.1_problem_answer.svg

    D-Xylose

    L-Fucose is a deoxy sugar. Fucose is is the monosaccaride L-galactose with the -OH group on C6 replaced with an -H.

    fucose.png

    N-acetylgalactosamine and N-acetylglucosamine are derivatives where the corresponding amino sugars have been converted to amides by N-acylation. Amino sugars have had their -OH groups at C2 replaced by an -NH2.

    clipboard_e3caad9a15abd877386d3a5185bb3a9d2.png

    N-Acetylneuraminic acid is nine carbon sugar created by an aldol reaction between N-acetymannosamine and pyruvate. N-acetylneuaminic acid forms a pyranose ring by a intramolecular hemiacetal formation between the -OH on C6 and the ketone functional group in the pyruvate moiety.

    clipboard_ea2a2f4c7d668d4262b8e252617bbce06.png

    Exercise \(\PageIndex{1}\)

    1) Please show the mechanism of the aldol reaction between N-acetylmannosamine and pyruvate to form neuraminic acid.

    Answer

    1)

    fucose.png


    5.1.8: The Eight Essential Monosaccharides is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Steven Farmer & Dietmar Kennepohl.