The mechanism of fatty acid synthesis from acetyl CoA § and malonyl CoA is known in great detail from studies with liver and yeast enzymes." 2 In these soluble systems the end products are long-chain saturated acids predominantly 16 carbon atoms in length. On the other hand, monounsaturated fatty acids are formed by liver and yeast in distinctly separate processes involving an oxidative introduction of double bonds into saturated precursors of equal chain length.3' This oxygen-requiring process appears to be widely distributed but is known not to take place in anaerobic microorganisms or other species of the order Eubacteriales.5 In the latter organisms the processes introducing double bonds are Cnaerobic and occur during the chain lengthening process rather than afterwards.Studying the metabolism of fatty acids in growing cultures of C. butyricum we have elucidated some aspects of this anaerobic pathway and have presented evidence that it involves the chain-lengthening of decanoate or octanoate by way of 3,y-unsaturated intermediates.6' 7 We now report the isolation of a soluble enzyme system from E. coli which catalyzes the condensation of acetyl CoA and malonyl CoA but differs from previously described fatty acid synthetases by producing both long-chain monounsaturated and saturated fatty acids. The E. coli enzyme has the further novel property of catalyzing a dehydration of f3-hydroxyacyl CoA to ,By-as well as a,4-enoyl derivatives.Materials and Methods.-2-C'4-Malonic acid and 1-C'4-octanoic acid were purchased from the New England Nuclear Corporation. trans-2-Decenoic acid was a product of the Aldrich Chemical Co. cis-2-Decenoic acid and cis-3-decenoic acid were prepared by P. E. Baronowsky of this laboratory. Published procedures were used for the preparation of acetyl CoA8 and malonyl CoA.9 TPN, G-6-P, G-6-P-dehydrogenase and l)Nase were obtained from commercial sources. Ammonium sulfate was recrystallized from Versene-ammonia solution.DL-3-C'4-3-hydroxydecanoic acid: Methyl 3-C'4-3-ketodecanoate was prepared from 1-Cl4-octanoyl chloride and acetoacetic ester by a slight modification of the method of Hunsdiecker."0 The ,3-ketoester was reduced to the ,B-hydroxyester with sodium borohydride in isopropanol. The saponified product was purified by silicic acid chromatography and crystallization from pentane, mp 53-55°, reported 56.50.11 Gas-liquid chromatography of the methyl ester on a diethyleneglycolsuccinate-polyester column showed a single peak with a retention time of 0.46 relative to methyl stearate. DL-3-C'4-3-hydroxydecanoyl CoA: This was prepared by the methods of Wieland and Rueff"2 and Goldman and Vagelos, 13 modified as follows. The precipitation by perchloric acid was omitted and instead the aqueous solution of the CoA derivative extracted with ether at pH 3 to remove unreacted hydroxy acid. The solution was then neutralized (pH 6-6.5) and lyophilized. The yield of CoA derivative was approximately 25%.Enzyme preparation: E. coli B cells were grown in defined media at 37014 with shaking for 14-16...

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Several 0-diketones were aroylated at the terminal methyl group with aromatic esters by means of two molecular equivalents of potassium amide in liquid ammonia to form 1,3,5-triketones. The triketone from 2-acetylcyclohexanone and methyl benzoate evidently consisted of two isomeric forms which were interconvertible. The triketones were cyclized with acid to form 4-pyrones, and with ammonia or methylamine to give 4-pyridones. These reactions furnish convenient methods of synthesis of such compounds. Mechanisms are considered.Recently2 3acetyl-and benzoylacetones were benzoylated at the terminal methyl group to form the corresponding 1,3,5-triketones, which were cyclized to give pyrones

Hexane extracts of the air-dried cortex of the gorgonian Plexaura homomalla (Esper) were found to contain (15R)-hydroxy-9-oxo-prost-5,10,13-trienoic acid [i.e. (15R)-prostaglandin A,] and its 15-acetate methyl ester in 0.Zo/, and 1.3O/, yield from the cortex by Weinheimer and Spraggins in 1969. Chloroform-methanol extracts of this organism have now been shown to contain these two compounds as major prostaglandin constituents, but also a more complex mixture of prostaglandin derivatives including lln,(l5R)-dihydroxy-9-oxo-prost-5,13-dienoic acid [i.e. (15R)-prostaglandin E,] and the methyl esters of (15R)-prostaglandin E, and (15R)-prostaglandin A,. (15R)-Prostaglandin E, was identified by its chromatographic behavior, by the chromatographic behavior and mass spectrum of its 0-methyloxime, methyl ester, trimethylsilyl ether derivative, and by oxidative ozonolysis to fragments of established structure. The configuration of the 15-hydroxyl group was determined in the cleavage fragment 2-hydroxyheptanoic acid by gas-liquid chromatography of its methyl ester ( -)-menthyloxycarbonyl derivative. Similar degradations of material with chromatographic properties equivalent to prostaglondin A, and prostaglandin E, yielded 2-hydroxyheptanoate with the 8 configuration, demonstrating the presence o€ small amounts of (158)-prostaglandins in the lipid extract.Weinheimer and Spraggins [l] reported the isolation of two prostaglandins, 15-acetyl-( 15R)-prostaglandin A, methyl ester (I) and (15R)-prostaglandin A, (111), from hexane extracts of the airdried cortex of the gorgonian Plexaura homomalla (Esper). The two substances were present in rather high concentrations, 1.3O/, and 0.2O/, of the cortex dry weight, respectively. These C-15 epimers of prostaglandin A, (IV) were devoid of the bloodpressure-lowering effect of prostaglandin A,. Their function in the gorgonian tissue is unknown, but their occurrence is very interesting since the concentration of prostaglandins normally found in various mammalian tissues is much smaller [Z]. They are also of interest as potential synthetic precursors to biologically active prostaglandins of the Az, Ez (VII), or FzG( type [3] because they can be obtained in large quantities.Trival names. Prostaglandin E,, lla-(l5L9)-dihydroxy-9-oxoprost-5,13-dienoic acid; prostaglandin FZa, 9a,1 la,-(15S)-trihydroxy-prost-5,13-dienoic acid; prostaglandin A,, (15S)-hydroxy-9-oxo-prost-5,10,13-trienoic acid; (15 R)-prosttaglandin E,, l l n , (15R)-dihydroxy-9-oxoprost-5,13-dienoic acid; (15R) prostaglandin A,, (15R)-hydroxy-9-oxo-prost-5,10,13-trienoic acid; methyl acetyl (15R)-prostaglandin A,, methyl (15R)-acetoxy-9-oxo-prost-5,10,13-trienoate.Definition. C-value, the "theoretical" number of carbon atoms in the fatty acid chain obt,ained from the retention time by using a calibration curve of logarithm of retention time versus number of carbon atoms in normal fatty acids.Our own interest in the gorgonians originated in their potential use as source of the prostaglandin synthetase. A prerequisite for such ...