https://wiki.tiffa.net/w/index.php?action=history&feed=atom&title=Translations%3AVitamin_B12%2F57%2Fen 2026-07-09T21:56:27Z Revision history for this page on the wiki MediaWiki 1.43.0 https://wiki.tiffa.net/w/index.php?title=Translations:Vitamin_B12/57/en&diff=135251&oldid=prev 2024-04-05T11:15:36Z

<p>Importing a new version from external source</p> <p><b>New page</b></p><div>==Chemistry==<br /> [[File:B12 methylcobalamin.jpg|thumb|200px|Methylcobalamin (shown) is a form of vitamin B&lt;sub&gt;12&lt;/sub&gt;. Physically it resembles the other forms of vitamin B&lt;sub&gt;12&lt;/sub&gt;, occurring as dark red crystals that freely form cherry-colored transparent solutions in water.]]<br /> Vitamin B&lt;sub&gt;12&lt;/sub&gt; is the most chemically complex of all the vitamins. The structure of B&lt;sub&gt;12&lt;/sub&gt; is based on a [[corrin]] ring, which is similar to the [[porphyrin]] ring found in [[heme]]. The central metal ion is [[cobalt]]. As isolated as an air-stable solid and available commercially, cobalt in vitamin B&lt;sub&gt;12&lt;/sub&gt; (cyanocobalamin and other vitamers) is present in its +3 oxidation state. Biochemically, the cobalt center can take part in both two-electron and one-electron reductive processes to access the &quot;reduced&quot; (B&lt;sub&gt;12r&lt;/sub&gt;, +2 oxidation state) and &quot;super-reduced&quot; (B&lt;sub&gt;12s&lt;/sub&gt;, +1 oxidation state) forms. The ability to shuttle between the +1, +2, and +3 oxidation states is responsible for the versatile chemistry of vitamin B&lt;sub&gt;12&lt;/sub&gt;, allowing it to serve as a donor of deoxyadenosyl radical (radical alkyl source) and as a methyl cation equivalent (electrophilic alkyl source).</div>

FuzzyBot