DOLICHOL: A NATURALLY-OCCURRING C100 ISOPRENOID ALCOHOL

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Abstract
The isolation and purification of dolichol from pig liver and from human kidney are described. The equivalent weight of the alcohol was found to be near 1380. Mass spectrometry and depression of the freezing point of cyclohexane showed that this was also the molecular weight. Infrared analysis indicated that the alcohol was isoprenoid and contained mainly cis isoprene units. Nuclear magnetic resonance confirmed this and the spectrum was that expected of a compound with the structure [image] containing 15 or 16 internal isoprene units in the cis configuration. Iodine value, hydrogen uptake and ultraviolet absorption were essentially in agreement with the presence of 19 double bonds/molecule. Ozonolysis of the p-nitrobenzoate yielded acetone, laevulinaldehyde and 4-methyl-6-p-nitrobenzoylhexanoic acid, as expected. The alcohol showed slight optical activity. Attempts to form a thiourea inclusion compound and to detect the presence of an ether linkage failed. A possible explanation for the apparently anomalous mobility of dolichol on paper chromatograms is considered. The possibility is discussed that hepene, previously regarded as a hydrocarbon, was really dolichol.