Presqualenyl-pyrophosphate (PSPP) was synthesized from farnesyl-pyrophosphate (FPP). The purified product could be transformed into a squalene in 90% yield. The structure of PSPP was established by the following experiments:1) PSPP displays a remarkably acid-labile phosphate-ester bond. Analogous to FPP it was possible to stabilize this bond by the addition of bromine. This indicates a structure of the allylester type.2) On acid hydrolysis PSPP splits off not only the pyrophosphate but also water. This may be best explained by the presence of a tertiary hydroxyl group in PSPP.3) The pyrophosphate group of PSPP could be split by prostatic phosphatase. In gas-liquid-chromatography the trimethyl-silylated product gave a single peak. From the mass spectra of this compound and of the corresponding alcohol the expected molecular weight of 426 could be verified for the latter.4) Determining the 3H/(14)C ratio in 1-(3)H(2)-4(14)C-FPP and in PSPP and squalene, synthesized from it, only three 3H-atoms could be detected in PSPP and in squalene.5) Ozonisation of PSPP, synthesized from 1-(14)C-FPP, gave radioactive malondialdehyde, which was characterised as azobenzene-malondialdehyde and 4-azobenzene-1-phenyl-pyrazole. The experimental results are in agreement with the following structure of 2, 6, 10, 15, 19, 23-hexamethyl-n-tetracosa-2, 6, 11, 14, 18, 22-hexaen-10-yl-pyrophosphate for PSPP.
Wasner
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Max-Planck-Institut für Zellchemie und Biochemisches Institut der Universität München, DBR, Germany
Lynen
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Die chemische struktur der biosynthetischen vorstufe des squalens.