Die chemische struktur der biosynthetischen vorstufe des squalens

Abstract

Presqualenyl-pyrophosphate (PSPP) was synthesized from farnesyl-pyrophosphate (FPP). The purified product could be transformed into 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/14C ratio in 1-3H2--414C-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 1-14C-FPP, gave radioactive malondialdehyde, which was characterised as azobenzene-malondialdehyde and 4-azobenzene-l-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-ylpyrophosphate for PSPP.