De novo biosynthesis of alkylacetylglycerols, a precursor of platelet activating factor (PAF)

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5283144

Malone, B; Lee, T C; Snyder, F

Alkylacetylglycerols are synthesized from 1-alkyl-2-lyso-sn-Gro-3-P via an acetyltransferase (I) and a phosphohydrolase (II). The final step that forms PAF in this pathway is catalyzed by a dithiothreitol-insensitive cholinephosphotransferase. This report describes properties of the acetyltransferase (I) and the phosphohydrolase (II). Results indicate the two activities are distinctly different from acetyl-CoA:1-alkyl-2-lyso-GroPCho acetyltransferase (III) and phosphatidic acid phosphohydrolase (IV), respectively. For example, 12.5 or 25 ..mu..M alkyl-lysoGroPCho did not affect the quantity of alkylacetylGroP and alkylacetylGro produced. The pH optimum for (I) was 8.4 as opposed to 6.9 for (III); also (I) and (III) had different sensitivities when microsomes were preincubated at various temperatures. Phosphatidic acid had no effect on the hydrolysis of the phosphate from alkylacetylGroP (II) and the pH optimum of the phosphohydrolase (II) was 6.6. Based on the distribution of marker enzymes, both acetyltransferases (I and III) and the alkylacetylGroP phosphohydrolase (II) are of microsomal origin. The phosphohydrolase (II) activity can be maximally inhibited by adding Na/sub 3/VO/sub 4/ and NaF to the assays and further decreased by incubating samples at a reduced temperature (23/sup 0/C); under these conditions the amounts of alkylacethlGroP is maximum. The newly identified enzyme activities (I and II) are relatively high in a variety of rat tissues, which suggests this de novo route is responsible for maintaining physiological levels of PAF.

• Research Organization: Oak Ridge Associated Universities, TN
• DOE Contract Number: AC05-76OR00033
• OSTI ID: 5283144
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ALCOHOLS
ANIMALS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
BLOOD COAGULATION FACTORS
CELL CONSTITUENTS
COAGULANTS
DRUGS
ENZYME ACTIVITY
ENZYMES
GLYCEROL
HEMATOLOGIC AGENTS
HYDROLASES
HYDROXY COMPOUNDS
MAMMALS
MICROSOMES
ORGANIC COMPOUNDS
ORGANOIDS
PH VALUE
PHOSPHOHYDROLASES
PRECURSOR
RATS
RODENTS
SYNTHESIS
TRANSFERASES
VERTEBRATES