THE FUNCTION OF CYTIDINE DIPHOSPHATE DIGLYCERIDE IN

THE FUNCTION OF CYTIDINE DIPHOSPHATE DIGLYCERIDE IN THE ENZYMATIC SYNTHESIS OF INOSITOL MONOPHOSPHATIDE1. Henry Paulus, and ...
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been obtained : (1) C T P L-a-glycerophosphate 2 RCO-S-CoA -+ + CDP-diglyceride; ( 2 ) CDP-diglyceride inositol -+ inositol monophosphatide CIZTP. When C Y ~ - P ~ ~ - P -DL-a-glycerophosphate P are incubated with an acylating system (,ITP, Co.4 and oleic acid) in the presence of an enzyme preparation from guinea pig liver, an extensive conversion to a labeled ether-soluble nucleotide occurs (Table I ) . This compound does not accumulate if myo-inositol is added to the system, indicating the occurrence of reaction (2). The conversion of L-a-glycerophosphate to CDP-diglyceride presumably involves a series of steps, which have not yet been studied in detail, but which may involve either phosphatidic acid or CDP-glycerol as intermediates.

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fluorine containing steroid was acetylated with acetic anhydride, Q-toluenesulfonic acid,j then treated with methanol and hydrochloric acid to hydiolyze any enol acetate that may have formed. The resulting material was chromatographed on silica gel. By the rechromatography of the crystalline steroid eluted with 10ycethyl acetate in benzene, there was obtained 6-methyl-17a-acetoxy-21TABLE I fluoro-4,6-pregnadiene-3,2O-dione (1I)'j; m.p. 222223'; [ a ] -2.5' ~ (CHC13); X ~ ~ ~ h a n 288 o l mp, CONVERSION O F CYT-P3*-P-P TO CDP-DIGLYCERIDE System: Cyt-P32-P-P, 1.0 pmole (37,000 c.p.ni.); DL( E 23,300); : : :A 5.73, 5.93, 6.13, 6.31, 7.88 and 8.05 cu-glycerophosphate, 1.0 pmole; CoA, 0.2 pmole; oleic acid, p ; (found: C, 71.78; H, 7.91). 0.1 pmole; ATP, 5 pmoles; iMnClz, 3 pmoles; MgCL, When tested orally in the Clauberg assay7 a t a 3 pmoles; 0.5 ml. of a dialyzed whole homogenate of guinea level producing a + 2 degree of glandular arboriza- pig liver in 0.05 M phosphate buffer, pH 7.4. The final tion, compound I1 was 17 times as potent as subcu- volume was 1.5 ml. Incubation was for 1 hour at 37". lipids were extracted with hot methanol, transferred taneous progesterone or 1700 times as potent as The t o ether, and an aliquot of the washed ether phase mas oral progesterone. It was three times as potent counted. orally as 6a-methyl-17a-a~etoxyprogesterone.~~ -4dditions. . . . . , . , , , . , . . . . . . None 1 pmcile myo-inositol (5) R . B. Turner, THISJ O U R N A L , 75, 3489 (1963). (6) A. Bowers and H . J. Ringold [ibid., 80, 3091 (1938) I have treated ll-oxo-6a-methyl-17a-hydroxyprogesterone with iodine ( 2 . 1 moles/ mole of steroid) a n d calcium oxide (9.G moles/mole of steroid) in tetrahydrofuran-methanol in practically t h e same way as we have treated 6a-methyl-17a-hydroxyprogesterone ( I ) , b u t they have not reported t h e formation of any 6-methyl-6-dehydrosteroid. It should be noted t h a t t h e 6.7-double bond probably was introduced during t h e iodination. T h e crude iodo-compound had a maximum in t h e ultraviolet a t 291 mp, ( t 10,500). (7) C. W. Emmens, "Hormone Assay." Academic Press, Inc., S e w York, N. Y.,1950, p. 422.

CDP-diglyceride, mpmoles

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For the direct study of reaction (2) CDPdipalmitin was synthesized from C M P and dipalmitoyl-DL-a-glycerophosphoric acid by a method essentially similar to that used for the synthesis of CDP-cho1ine.j The CDP-dipahitin was precipitated as the barium salt from aqueous solution, dissolved in chloroform-methanol by the addition of hydrogen chloride and chromatographed G. D. SEARLE A N D COMPANY P. B. SOLLMAN on silicic acid. It was eluted at about 20Yc methP. 0. Box 5110 I