The chemical side of nervous activity. Croonian lectures no 1.

  • Halliburton, W. D.
Date:
1901
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Licence: In copyright

Credit: The chemical side of nervous activity. Croonian lectures no 1. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    It is a complex fat of wide distribution, being a constituent of protoplasm. The tables of analyses already given show its quantitative importance in nervous structures. When it is decomposed, either in the laboratory or in the body, it breaks up into three substances, as shown in the following equation :— C^H^NPO, + 3H20 = 2Cl8H3602 + C3H9P06 + CsHI5N02 [lecithin] [stearic acid] [glycero- [choline] phosphoric acid] There are other lecithins present in smaller quantities which yield other fatty acids on decomposition. To give the fore- going lecithin its chemical name we must call it choline-distearyl- glycero-phosphoric acid. The choline radicle is united to the acid by means of the oxygen of the hydroxyl, it is therefore not a salt but an ether-like combination, thus :— CH20 - CI7H35CO CHO -CI7H35CO CH.O-PO-O.C2H4) I (CH3)3 N. OH HO The same facts can be put more simply by comparing an ordinary fat with lecithin. An ordinary neutral fat such as those which are found in adipose tissue or milk contains only three elements, carbon, oxygen and hydrogen. Lecithin contains the same three elements with nitrogen and phosphorus in addition. An ordinary neutral fat on decomposition links to itself the elements of water, and then splits up (is hydrolysed) into glycerin and a fatty acid ; thus stearin yields stearic acid and glycerin ; palmitin, palmitic acid and glycerin ; and olein, oleic acid and glycerin. Fat + water Fatty acid Glycerin. Lecithin yields not only a fatty acid and glycerin, but in addition to these substances it gives rise to phosphoric acid, which contains all the phosphorus of the lecithin, and choline, an alkaloid which contains all the nitrogen of the lecithin. Lecithin + water Glycerin Fatty acid Phosphoric acid Choline.