Über eine in-vivo-Methode zur Herstellung radioaktiv markierter Phosphatide mit Sojabohnen / A Method for Preparing Radioactive Labeled Phosphatides Using Soybeans in-Vivo

Abstract

Germinating soybeans, when incubated for 20-30 hours under an illumination at 25°-30° temp, with labeled ³²P-phosphate, ¹⁴C-acetate, ¹⁴C-glycerol and ¹⁴C-choline, radioactivity ranging from 2 to 14% is incorporated into the main phosphatides lecithin (PC), phosphatidylethanolamine (PE) and monophosphoinositide (MPI). The incorporation of ³²P-phosphate in these phosphatides depending on light and temperature, increases to its maximum (3.7 mCi/1 g soybeans) almost running linear and continues further even in the absence of any further germination due to intensive exposure to radiation. ¹⁴C-acetate is incorporated almost exclusively into fatty acids of the phospholipids during germination as a result of which highest specific radioactivity was seen in the stearic acid followed by oleic acid and palmitic acid. Linol- and linolenic acid under these experimental conditions are weakly or not labeled, ¹⁴C-choline is incorporated only in PC. As the PC after ¹⁴C-(methyl) -methionine-incubation does not exhibit any significant labeling, one can exclude the pathway of PC-biosynthesis through PE-methylation. The utilization of ¹⁴C-glycerol proves that the incorporation of all the compounds under consideration here is effected not by a mere exchange but by a de novo synthesis. This procedure of labeling is suitable for preparing ³H-, ¹⁴C- and ³²P-PC, -PE, -MPI and phosphatidic acid (PA).