Fatty acid specificity of glyceride synthesis by homogenates of bovine mammary tissue

Fatty acid esterification by cell free preparations of bovine mammary tissue was investigated to determine if the type of long chain fatty acid supplied might influence the rate of triglyceride synthesis by that tissue. Homogenates of lactating bovine mammary tissue esterified¹⁴C-fatty acids into glycerides at rates dependent upon chain length and degree of unsaturation. Palmitic, stearic, oleic and linoleic acids were esterified at rates consistent with their concentration in milk fat. A comparison of free fatty acid concentrations of mammary tissue with levels saturating esterification suggested that supply of fatty acids does not limit glyceride synthesis. Certain combinations of fatty acids were facilitory, competitive or inhibitory to esterification. Stearic acid complimented esterification of palmitic and oleic acids. Unlabeledtrans-11-octadecenoic acid did not compete with¹⁴C-palmitate as efficiently in the esterification process as did unlabeledcis-9-octadecenoic acid, indicating that the mammary gland may preferentially esterify thecis-isomer of C-18∶1. Linoleic acid inhibited esterification of palmitic, stearic and oleic acids. Michigan Agricultural Experiment Station Journal Article No. 5100.     

Micro vapor-phase hydrogenation monitored with tanden chromatography-radioactivity: III. Isomeric monoenes

Micro vapor-phase hydrogenation and radiotracer techniques have been utilized to investigate the effect of geometric configuration and double bond position on the rate of hydrogenation of octadecenoates. These techniques provide for simultaneously monitoring the time course of vapor-phase hydrogenation both for an essentially pure monoene isomer by thermal conductivity and for methyl oleate by radioactivity. The two hydrogenations proceed independently but have identical parameters of temperature, flow rate and catalyst activity. The experimental data are plotted, relative reaction rates are calculated and theoretical curves are drawn by a digital computer system with plotter accessory. Experiments with nickel catalysts indicate that rates of reduction are affected by both the position and configuration of the double bond.cis-15-Octadecenoate is reduced 1.4 times faster than itscis-9 isomer. Bothcis-9- and -12-octadecenoate are reduced at approximately equal rates.cis-9-Octadecenoate was reduced 1.4 times as fast as thecis-6 isomer. Oleate was reduced 1.27 times as fast as elaidate. Presented at AOCS Meeting, Chicago, October 1967. Utiliz. Res. Dev. Div., ARS, USDA     

Partial reduction of α-Eleostearic acid with hydrazine

The following products are formed during partial reduction of α-eleostearic acid with hydrazine:cis,trans-9,11-octadecadienoic andtrans,trans-11,13-octadecadienoic acids;cis-9-,trans-11- andtrans-13-octadecenoic acids; and stearic acid. The double bonds are reduced individually in the conjugated triene and also in the conjugated dienes that are formed. However, the reduction is selective since thetrans-11 double bonds in the conjugated triene is reduced only slightly to yield the isolated 9,13-diene. Thetrans double bond of thecis,trans conjugated diene reduces at a faster rate than thecis bond. No differences were observed in the rate of reduction of thecis-9 andtrans-13 bonds in the triene or of the bonds in thetrans,trans conjugated diene. No. Utiliz. Res. & Dev. Div., ARS, USDA.     

Oxygenated fatty acids of oil from sunflower seeds after prolonged storage

Chemical analysis of a number of sunflower (Helianthus annuus) seed oil samples revealed a low and variable percentage of hydrogen bromide-reactive material. To characterize the compounds responsible for this reactivity, oil was extracted from selected introductions from Uruguay, Turkey, and Yugoslavia that had been subjected to prolonged storage. Two epoxy fatty acids and two conjugated dienolic acids were isolated from the methyl esters derived from these sunflower seed oils by using a combination of column chromatography and countercurrent distribution. The epoxy acids arecis-9,10-epoxystearic acid (0.5%) andcis-9,10-epoxy-cis-12-octadecenoic (coronaric) acid (2.2%). Characterization of the dienols revealed that they are 9-hydroxy-trans-10,cis-12-octadecadienoic acid (1.2%) and 13-hydroxy-cis-9,trans-11-octadecadienoic acid (1.3%). Fresher seed of some of these introductions contained less of the oxygenated components. Oil from recently produced seed of selected high-oil Russian sunflower varieties, including some currently grown in the United States, contained no more than trace amounts of oxygenated acids. Though the relative contributions of genetic and environmental factors toward genesis of oxygenated acids are not established, increase of those acids in some sunflower lines as a result of storage has been demonstrated. Presented at the AOCS-AACC Joint Meeting, Washington, D. C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Participation of thecis-12 ethylenic bond tocis-trans isomerization of thecis-9 andcis-15 ethylenic bonds in heated α-linolenic acid

To understand thecis-trans isomerization reaction of ethylenic bonds in heated octadecatrienoic acids (occurring during industrial deodorization of oils), we have prepared a mixture ofcis-9,cis-12,cis-15, andcis-9,cis-15 18:2 acids by partial hydrazine reduction ofcis-9,cis-12,cis-15 18:3 acid present in linseed oil. This mixture (as fatty acid methyl esters) was heated under vacuum at 270°C for 2.25 h. The two methylene-interrupted acids isomerize at a similar rate under such conditions, but the nonmethylene-interruptedcis-9,cis-15 18:2 acid remains unchanged. This means that the mechanism of isomerization does not involve a direct interaction between the two external ethylenic bonds as previously hypothesized. The centralcis-12 ethylenic bond is apparently necessary for the isomerization of the two externalcis-9 andcis-15 ethylenic bonds. However, this bond is itself rather protected against isomerization in the originalcis-9,cis-12,cis-15 18:3 acid which is mainly isomerized totrans-9,cis-12,trans-15,cis-9,cis-12,trans-15, andtrans-9,cis-12,cis-15 18:3 acids. Thecis-9,trans-12,cis-15 18:3 isomer is less than 10% of totaltrans isomers of α-linolenic acid. As a general rule, only one of the two double bonds in a methylene-interrupted diethylenic system can undergocis-trans isomerization when submitted to heat treatment, at least for temperatures equal to or less than 270°C.     

Formation of γ-ketols from 13- and 9-hydroperoxides of linolenic acid by flaxseed hydroperoxide isomerase

A reexamination of the flaxseed hydroperoxide isomerase reaction showed that a minor enzymic product (ca. 5%), identified as a γ-ketol, was present. The substrates were the 13- or 9-hydroperoxides of linolenic acid, which were converted to 9-hydroxy-12-oxo-cis-15-trans-11-octadecadienoic acid, respectively. These compounds were formed in addition to the major products reported earlier: a 12,13-α-ketol and 12-oxo-cis-10,15-phytodienoic acid from the 13-isomer, and a 9,10-α-ketol from the 9-isomer.     

Effects of cis-9, trans-11 and trans-10, cis-12 CLA isomers on liver and adipose tissue fatty acid profile in hamsters

The aim of the present study was to investigate the effect of cis-9, trans-11 and trans-10, cis-12 CLA on FA composition of TAG in epididymal adipose tissue and liver, and of hepatic phospholipids PL. Twenty-four Syrian Golden hamsters were randomly divided into three groups of eight animals each and fed semipurified atherogenic diets supplemented with either 0.5 g/100g diet of linoleic acid or cis-9, trans-11 or trans-12, cis-9 CLA for 6 wk. Total lipids were extracted, and TAG and PL were separated by TLC. FA profile in lipid species from liver and adipose tissue, as well as in feces, was determined by GC. Trans-10, cis-12 CLA feeding significantly reduced linoleic and linolenic acids in TAG from both tissues, leading to reduced total PUFA content. Moreover, in the epididymal adipose tissue docosenoic and arachidonic acids were significantly increased. In liver PL, although no changes in individual FA were observed, total saturated FA (SFA) were decreased. No changes in TAG and PL FA profiles were induced by the cis-9, trans-11 CLA. TAG and PL incorporated cis-9, trans-11 more readily than trans-11, cis-12 CLA. This difference was not due to differential intestinal absorption, as shown by the analysis of feces. We concluded that only trans-10, cis-12 CLA induces changes in FA composition. Whereas increased PUFA content was observed in either liver or adipose tissue TAG, decreased SFA were found in liver PL. Incorporation of cis-9, trans-11 CLA in TAG is greater than that of trans-10, cis-12 CLA, but this is not due to differences in intestinal absorption.     

Tuna fatty acids: I. initial studies on the composition of the light and dark meats of bluefin tuna (Thunnus thynnus)-structural isomers of the monoenoic fatty acids

Bluefin tuna (Thunnus thynnus) is consumed in substantial amounts by humans. However, little has been reported on the fatty acid composition of bluefin body oil and on the isomeric structures of the unsaturated fatty acids. Because of the probable nutritional significance of unsaturated fatty acids, the present work was undertaken as an introductory study of the composition and structure of the fatty acids of tuna. The fatty acid composition of the light and dark meats from three bluefin tuna was determined by gas-liquid chromatography. A wide variety of saturated and polyunsaturated fatty acids were present in the oil from the meat of these speciments. the monoemoic fatty acid fraction, which comprises 34% of the total fatty acids was isolated and the isomers determined. Isomers found werecis-9-hexadecenoic acid,cis-9-octadecenoic acid,cis-11-octadecenoic acid,cis-9-eicosenoic acid,cis-11-eicosenoic acid,cis-11-docosenoic acid, andcis-13-docosenoic acid. Division of Industrial Research, U.S. Fish and Wildlife Service, Department of the Interior.     

OxygenatedTrans-3-olefinic acids in aStenachaenium seed oil

Interesting differences were found in oils from two samples ofStenachaenium macrocephalum (Compositae) seed with dissimilar storage histories. One contained significant amounts of epoxy acids (6.5%) and hydroxy conjugated dienoic acids (5.6%), but the other contained no more than 1% of these oxygenated acids. Characterization of components in the former oil established that the principal epoxy acid (4.0%) is the previously unknowncis-9, 10-epoxy-trans-3,cis-12-octadecadienoic acid. The conjugated dienols include two additional new acids with Δ3 unsaturation (2.5%): 9-hydroxy-trans-3,-trans-10,cis-12-octadecatrienoic and 13-hydroxy-trans-3,cis-9,trans-11-octadecatrienoic acoids. The nonoxygenated acids, except for the large amount (40%) oftrans-3,cis-9,cis-12-octadecatrienoic, are those that commonly occur in seed oils. Presented at the AOCS Meeting, San Francisco, April 1969. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Microbial hydration ofCis-9-alkenoic acids

The activity of acis-9-fatty acid hydratase produced by aPseudomonas sp. (NRRL B-3266) isolated from soil was compared with that of another isolate previously reported (NRRL B-2994). The presence of appropriate fatty acids for at least 4 hr during aerobic growth in yeast extract medium increased subsequent enzyme activity. Such cells anaerobically hydrated severalcis-9-alkenoic acids to 10-hydroxy fatty acids and aerobically formed 10-keto acids, which were partially degraded to shorter chain keto acids. Melting point, gas chromatography, infrared, mass spectrometry and optical rotatory dispersion data are given. Six fatty acids havingcis-9-unsaturation produced hydrated products, but several enoic acids havingtrans-9-unsaturation or double bonds in other than the 9 position were inactive as substrates. The (−)-10-hydroxypalmitic acid produced from palmitoleic acid is considered to have the D configuration. Yields of 71% crude crystalline product from 15 g of oleic acid and 53% from 11 g of palmitoleic acid were obtained in 5-liter anaerobic fermentations with NRRL B-3266. Methyl esters, triolein and oleyl alcohol were not hydrated. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Homolytic decomposition of linoleic acid hydroperoxide: Identification of fatty acid products

An isomeric mixture of linoleic acid hydroperoxides, 13-hydroperoxy-cis-9,trans-11-octadecadienoic acid (79%) and 9-hydroperoxy-cis-12,trans-10-octadecadienoic acid (21%), was decomposed homolytically by Fe(II) in an ethanol-water solution. In one series of experiments, the hydroperoxides were decomposed by catalytic concentrations of Fe(II). The 10⁻⁵ M Fe(III) used to initiate the decomposition was kept reduced as Fe(II) by a high concentration of cysteine added to the reaction in molar excess of the hydroperoxides. Nine different monomeric (no detectable dimeric) fatty acids were identified from the reaction. Analyses of these fatty acids revealed that they were mixtures of positional isomers identified as follows: (I) 13-oxo-trans,trans-(andcis,trans-) 9,11-octadecadienoic and 9-oxo-trans,trans- (andcis,trans-) 10,12-octadecadienoic acids; (II) 13-oxo-trans-9,10-epoxy-trans-11-octadecenoic and 9-oxo-trans-12, 13-epoxy-trans-10-octadecenoic acids; (III) 13-oxo-cis-9,10-epoxy-trans-11-octadecenoic and 9-oxo-cis-12, 13-epoxy-trans-10-octadecenoic acids; (IV) 13-hydroxy-9,11-octadecadienoic and 9-hydroxy-10,12-octadecadienoic acids; (V) 11-hydroxy-trans-12, 13-epoxy-cis-9-octadecenoic and 11-hydroxy-trans-9, 10-epoxy-cis-12-octadecenoic acids; (VI) 11-hydroxy-trans-12, 13-epoxy-trans-9-octadecenoic and 11-hydroxy-trans-9,10-epoxy-trans-12-octadecenoic acids; (VII) 13-oxo-9-hydroxy-trans-10-octadecenoic acids; (VIII) isomeric mixtures of 9, 12, 13-dihydroxyethoxy-trans-10-octadecenoic and 9, 10, 13-dihydroxyethoxy-trans-11-octadecenoic acids; and (IX) 9, 12, 13-trihydroxy-trans-10-octadecenoic and 9, 10, 13-trihydroxy-trans-11-octadecenoic acids. In another experiment, equimolar amounts of Fe(II) and hydroperoxide were reacted in the absence of cysteine. A large proportion of dimeric fatty acids and a smaller amount of monomeric fatty acids resulted. The monomeric fatty acids were examined by gas liquid chromatography-mass spectroscopy. Spectra indicated that the monomers were largely similar to those produced by the Fe(III)-cysteine reaction. Presented in part at the American Chemical Society Meeting, Los Angeles, March 1974. ARS, USDA.     

Structural importance of thecis-5 ethylenic bond in the endogenous desaturation product of dietary elaidic acid,cis-5,trans-9 18∶2 acid,for the acylation of rat mitochondria phosphatidylinositol

When rats were fed elaidic (trans-9 18∶1) acid at a high load in diets that were otherwise marginally or almost completely deficient in linoleic (cis-9,cis-12 18∶2) acid, elaidic acid was desaturated tocis-5,trans-9 18∶2 acid. This polymethylene-interrupted acid was then incorporated into most phospholipids from rat mitochondria, cardiolipin being an exception. Its level of esterification in phospholipids followed the increasing order: phosphatidylethanolamine <phosphatidylcholine < phosphatidylinositol (PI). The content ofci-5,trans-9 18∶2 acid decreased in organs in the order liver > kidney > heart. The levels ofcis-5,trans-9 18∶2 acid increased in mitochondria phospholipids as the level of linoleic acid was lowered in the diet. In liver mitochondria PI, it reached 16% of total fatty acids. After hydrolysis of liver mitochondria PI withNaja naja phospholipase A₂, we observed that elaidic acid was essentially esterified to position 1 at the expense of saturated acids, whereascis-5,trans-9 18∶2 acid was exclusively esterified to position 2, along with 20∶3n−9 and 20∶4n−6 acids. As a consequence, the sums of saturated andtrans-9 18∶1 acids on the one hand, and of 20∶3n−9, 20∶4n−6, andcis-5,trans-9 18⩺2 acids on the other hand, remained fairly constant in liver mitochondria PI (ca. 55 and 30%, respectively). Becausetrans-9 18∶1 andcis-5,trans-9 18∶2 acids differ only by thecis-5 ethylenic bond, which is also present in 20∶3n−9 and 20∶4n−6 acids, this distribution pattern indicates that thecis-5 double bond, rather than any other ethylenic bond, may be of major structural importance for channeling fatty acids to position 2 of PI.     

New synthesis ofcis-3,cis-5- andtrans-3,cis-5-tetradecadienoic acids,pheromone constituents ofattagenus elongatulus andA. megatoma

A new method for the synthesis ofcis-3,cis-5- andtrans-3,cis-5-tetradecadienoic acids, pheromone constituents of the dermestid beetlesAttagenus elongatulus andA. megatoma, was developed. The syntheses are based upon the formation oftrans-2-tetradecen-5-ynoic acid by reaction of 4-bromo-2-butenoic acid with 1-decynylmagnesium bromide. The enynoic acid undergoes alkali-induced isomerization to yield a mixture of acids from whichcis-3- andtrans-3-tetradecen-5-ynoic acids were separated in 31% and 34% yields, respectively. Methyltrans-2-tetradecen-5-ynoate was similarly prepared and isomerized to furnish methylcis-3-tetradecen-5-ynoate in 8% yield. Reduction of the tetradecenynoic acids with dicyclohexylborane gavecis-3,cis-5-andtrans-3,cis-5-tetradecadienoic acids in 4% and 39% yields, respectively. A better yield (49%) in the reduction ofcis-3-tetradecen-5-ynoic acid tocis-3,cis-5-tetradecadienoic acid was obtained by hydrogenation over Lindlar's catalyst. Similarly, reduction of methylcis-3-tetradecen-5-ynoate with disiamylborane gave 22% methylcis-3,cis-5-tetradecadienoate.     

Steric configurations of parinaric and punicic acids

GLC analysis of the scission products from the fractions separated by silver nitrate-silicic acid column chromatography of the hydrazine reduced products has shown that parinaric and punicic acids have (cis-9,rans-11,trans-13 andcis-15) and (cis-9,trans-11 andcis-13) configurations, respectively.     

Characterization of γ-linolenic acid geometrical isomers in borage oil subjected to heat treatments (deodorization)

Heating of borage oil, either under vacuum as a model or during steam-vacuum deodorization, produces artifacts that are geometrical isomers of γ-linolenic acid (cis-6,cis-9,cis-12 18∶3 acid). In a first approach, we have studied the behavior of these fatty acids in the form of either methyl or isopropyl esters on two capillary columns (CP-Sil 88 and DB-Wax). From this study, it appears that the DB-Wax capillary column is the best suited analytical tool to study in some detail γ-linolenic acid geometrical isomers. In a second approach, the structure of these isomers was formally established by combining several analytical techniques: Argentation thin-layer chromatography, comparison of the equivalent chainlengths with those of isomers present in NO₂-isomerized borage oil on two different capillary columns, partial hydrazine reduction, oxidative ozonolysis, gas chromatography coupled with mass spectrometry and gas chromatography coupled with Fourier transform infrared spectroscopy. The two main isomers that accumulate upon heat treatments are thetrans-6,cis-9,cis-12 andcis-6,cis-9,trans-12 18∶3 acids with minor amounts ofcis-6,trans-9,cis-12 18∶3 acid. One di-trans isomer, supposed to be thetrans-6,cis-9,trans-12 18∶3 acid, is present in low although noticeable amounts in some of the heated oils. The content of these artificial fatty acids increases with increasing temperatures and duration of heating. The degree of isomerization (DI) of γ-linolenic acid is less than 1% when the oil is deodorized at 200°C for 2 h. Heating at 260°C for 5 h increases the DI up to 74%. Isomerization of γ-linolenic acid resembles that of α-linolenic (cis-9,cis-12,cis-15 18∶3) acid in several aspects: The same kinds and numbers of isomers are formed, and similar degrees of isomerization are reached when the octadecatrienoic acids are heated under identical conditions. It seems that the reactivity of a double-bondvis-à-vis cis-trans isomerization is linked to its relative position, central or external, and not to its absolute position (Δ6, 9, 12 or 15).     

Positional and geometrical isomers of linoleic acid in partially hydrogenated oils

The geometrical and positional isomers of linoleic acid of a partially hydrogenated canola oil-based spread were isolated and identified. Through partial hydrazine reduction and mass spectral studies,cis-9,trans-13 octadecadienoic acid was identified as the major isomer. Other quantitatively important isomers characterized werecis-9,trans-12;trans-9,cis-12 andcis-9,cis-15. These four were also the major isomers in margarine based on common vegetable oils. A number of minor isomers were detected and some structures identified weretrans-9,trans-12;trans-8,cis-12;trans-8,cis-13;cis-8,cis-13;trans-9,cis-15;trans-10,cis-15 andcis-9,cis-13. The proportions of the various isomers are given for some margarines in the Canadian retail market. The amounts oftrans-9,trans-12 isomer in Canadian margarines were generally below 0.5% of the total fatty acids.     

Occurrence of γ-linolenic acid in compositae: A study of Youngia tenuicaulis seed oil

Seeds of Youngia tenuicaulis and other species from the plant family Compositae (Asteraceae) were studied for their oil content and fatty acid composition. The seed oil of Y. tenuicaulis growing in Mongolia was found to contain 5.6% γ-linolenic acid (18∶3Δ6cis,9cis,12cis) in addition to common fatty acids. The oil was analyzed using chromatographic [capillary gas-liquid chromatography (GLC), thin-layer chromatography] and spectroscopic (infrared, gas chromatography-mass spectrometry) techniques. Seed oil fatty acids of Saussurea amara (containing γ-linolenic acid) and of Arctium minus (containing 18∶3Δ3trans,9cis,12cis), as well as Δ5cis- and Δ5trans-18∶3 were used as GLC reference substances. The evolution in this plant family of a large number of different 18∶3 acids as well as the corresponding evolution of unusual desaturases should be investigated. On the other hand, the Δ6cis-desaturase required for the biosynthesis of γ-linolenic acid may have evolved independently several times in unrelated families of the plant kingdom.     

Cis-trans isomerization of octadecatrienoic acids during heating. Study of pinolenic (cis-5,cis-9,cis-12 18∶3) acid geometrical isomers in heated pine seed oil

To understand the heat-inducedcis-trans isomerization of ethylenic bonds in octadecatrienoic acids, pine seed oil, which contains the unusual nonmethylene-interrupted pinolenic (cis-5,cis-9,cis-12 18∶3) acid as a major component, was heated under vacuum at 240°C for 6 h together with linseed and borage oils. As a results, a small percentage of pinolenic acid undergoescis-trans isomerization. The main isomer that accumulates is thetrans-5,cis-9,trans-12 18∶3 acid. Minor amounts of the three mono-trans isomers are also present. Identification of isomers was realized by combining gas-liquid chromatography on a CP Sil 88 capillary column, argentation thin-layer chromatography and comparing the equivalent chainlengths of artifacts to those of isomers present in NO₂-isomerized pine seed oil. Hydrazine reduction was used to demonstrate that there was no positional shift of double bonds. Heat-induced geometrical isomerization of pinolenic acid differs from that of α- and γ-linolenic acids in at least two aspects. The reaction rate is slower (about one-fourth), and mono-trans isomers are formed in low amounts.     

Epoxy oils from plant seeds

Epoxy acids have been reported in seed oils from more than 60 species in 12 plant families. The discovery of 9,10-epoxyoctadec-12-ynoic and 9,10-epoxy-trans-3,cis-12-octadecadienoic acids brings to six the number of natural epoxy acids now known to occur in seed oils. These latest epoxy acids and 15,16-epoxy-cis-9,cis-12-octadecadienoic acid have been found in only one species each and at levels lower than 5% of the oil. Coronaric (9,10-epoxy-cis-12-octadecenoic) acid and 9,10-epoxystearic acid have been encountered in several seed oils, the first as much as 15% of the oil and the latter in only small amounts. Vernolic (12,13-epoxy-cis-9-octadecenoic) acid, which has been identified in numerous oils, is the only epoxy acid known to occur in seed oils at levels above 15%, and it may constitute as much as 75%. On the basis of data available to date,Vernonia anthelmintica appears to have the best potential for commercial production of an epoxy oil. Although one improved line has been selected, continued improvement is needed. Formation of epoxy acids in oilseeds during storage after harvest has been demonstrated, and may be partly responsible for the small amounts of epoxide detected in oils from a wide variety of seeds. Presented at the AOCS Meeting, New Orleans, April 1970. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Studies on the specificity of a lipase system fromGeotrichum candidum

The lipase system fromGeotrichum candidum preferentially hydrolyzed oleic acid, regardless of position, from the four possible racemic triglycerides containing oleate and palmitate. The rate of hydrolysis of these glycerides was most rapid when the substrate contained two moles of oleate. This acid was also preferentially released from a series of triglycerides containing oleate and two moles of a saturated fatty acid. The chain length of the latter did not alter the specificity for oleate. Equimolar quantities of oleic and linoleic acids were released when triolein and trilinolein (equimolar mixture) were hydrolyzed by this lipase. No differentiation between oleate and palmitoleate was observed when racemic glyceryl 1-palmitoleate-2,3-dioleate was the substrate. However, only 7.2 M%cis-vaccenic acid was released from glyceryl 1-cis-vaccenate-2,3-dioleate and 5.4 M% petroselinic acid from glyceryl 1-palmitoleate-2,3-dipetroselinate. It therefore appears that the enzyme may be specific forcis-9-unsaturation as well as forcis-9,cis-12-unsaturation. When specificity was assumed, the fatty acid compositions of the diglycerides obtained from digestions withG. candidum were close to theoretical. Scientific contribution No. 256, Agricultural Experiment Station, University of Connecticut, Storrs.