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11.2B: Vitamin B₁₂ Functions

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    The B12 Vitamin is a cofactor for 2 enzymes: Methionine synthase and Methylmalonyl mutase.

    Methionine Synthase

    Methionine synthase is an important enzyme in 1-carbon metabolism that uses methylcobalamin as its cofactor and converts homocysteine to methionine by adding a methyl group. Methionine then is converted to other compounds that serve as methyl donors, as shown below1.

    Figure 11.211: One-carbon metabolism

    methylating

    These methyl donors can donate methyl groups for DNA, an epigenetic modification1.

    Methymalonyl mutase

    adenosylcobalamin

    This enzyme uses as its cofactor, and is important in the breakdown of odd chain fatty acids (5 carbons etc.). As you know, odd chain fatty acids are less common than even chain fatty acids, but this enzyme is required to properly handle these less common fatty acids1.

    Demyelination

    In addition to its role as a cofactor for enzymes, vitamin is also important for preventing degradation of the myelin sheath that surrounds neurons, as shown below.

    1200px-Neuron_Hand-tuned.svg.png

    Figure 11.212: Vitamin B12 is needed to maintain the myelin sheath that surrounds neurons. (CC BY-SA 3.0; Quasar Jarosz).

    The mechanism through which vitamin prevents demyelination is not known3.

    References & Links

    1. Byrd-Bredbenner1. C, Moe G, Beshgetoor D, Berning J. (2009) Wardlaw's perspectives in nutrition. New York, NY: McGraw-Hill.
    2. infocentehttp://lpi.oregonstate.edu/3. ...ns/vitaminB12/

    Contributors and Attributions

    This page titled 11.2B: Vitamin B₁₂ Functions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Brian Lindshield via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.