Vitamer

Vitamer

The vitamers of a particular vitamin are all of the chemical compounds which exhibit vitamin activity. Very commonly "vitamins" are not single compounds, but rather each vitamin, which is defined by its biological activity, not its structure, is actually represented by a number of substances, all of which show vitamin activity. [ http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.bi.13.070144.002055 Accessed Jan 4, 2008. Early 1944 ref discussing reasons for introduction of word. ] Typically, the vitamin activity of multiple vitamers is due to the body's limited ability to convert one vitamer to another, or many vitamers to the same enzymatic cofactor(s). This is the case even though (as part of the definition of vitamin) the body cannot completely synthesize an optimal amount of vitamin activity from simple foodstuffs, without a minimal vitamer molecule as a basis.

Typically not all vitamers possess exactly the same vitamin potency, per mass. This is due to differences in absorption and interconversion of the various different vitamers of a vitamin. Often for the same reason, the toxicity of vitamers varies by molecule, as is the case with vitamin E. [ [http://jn.nutrition.org/cgi/content/abstract/134/12/3335 The Cytotoxicity of Vitamin E Is Both Vitamer- and Cell-Specific and Involves a Selectable Trait - McCormick and Parker 134 (12): 3335 - Journal of Nutrition ] ]

A set of chemicals may be (but is not always) grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A," which (for example) includes retinal, retinol, and many carotenoids. [ http://www.answers.com/topic/vitamer?cat=health#top See Oxford entry, accessed Jan 4, 2008. ] Examples of vitamers include cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5-deoxyadenosylcobalamin (adenosylcobalamin—AdoB-12), which are all vitamers of B-12, and thus all possess "B-12 activity". Another example is that both niacinamide and nicotinic acid (niacin) have vitamin B-3 activity.

External links

* [http://medical-dictionary.thefreedictionary.com/vitamer Dictionary definition of vitamer. Referenced Jan. 4, 2008]

References


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  • vitamer — vi·ta·mer (vīʹtə mər) n. One of two or more related chemical substances that fulfill the same specific vitamin function.   [vitamin + isomer.]   vi ta·merʹic ( mĕrʹĭk) adj. * * * …   Universalium

  • vitamer — noun Any of a combination of substances that, together, function as a vitamin …   Wiktionary

  • vitamer — One of two or more similar compounds capable of fulfilling a specific vitamin function in the body; e.g., niacin, niacinamide. * * * vi·ta·mer vīt ə mər n any of two or more compounds that relieve a particular vitamin deficiency also a structural …   Medical dictionary

  • Vitamer — Vita|me̱r [Kurzbildung zu ↑Vitamin u. ↑Isomer] s; s, e (meist Mehrz.): organische Verbindungen mit definierter Vitaminaktivität, die sich jedoch strukturell von dem eigentlichen Vitamin unterscheiden können …   Das Wörterbuch medizinischer Fachausdrücke

  • Vitamer — Vi|ta|mer das; s, e (meist Plur.) Kurzw. aus ↑Vitamin u. ↑Isomer> organische Verbindung mit Vitaminaktivität, die sich jedoch strukturell von dem eigentlichen Vitamin unterscheiden kann …   Das große Fremdwörterbuch

  • vitamer — n. substance which resembles a vitamin in its structure and function (Biochemistry) …   English contemporary dictionary

  • vitamer — vi·ta·mer …   English syllables

  • vitamer — …   Useful english dictionary

  • Cyanocobalamin — Identifiers CAS number 68 19 9  …   Wikipedia

  • Vitamin — This article is about the set of organic compounds. For the nutritional supplement preparation, see multivitamin. For the manga, see Vitamin (manga) …   Wikipedia

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