16 II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL 



petroselinic, erucic, and selacholeic acids. Since the cis compounds are 

 shorter than the trmis ones, it is known that they are bent back on them- 

 selves as indicated in the formulas for oleic and elaidic acids. For a further 

 discussion of cis-travs isomerism in the fatty acid, the reader is referred to 

 page 85. 



CH3(CH2)7CH CH3(CH2)7CH 



0\ II II yO 



H0-C(CH2)7CH HC(CH2)7C-0H 



Oleic acid Elaidic acid 



b. Vaccenic Acid. An isomer of oleic acid, vaccenic acid (11-octa- 

 decenoic acid), is of especial interest because of its occurrence in animal 

 fats such as butter, lard, mutton, and beef fats ^*~^^ and its absence from 

 such vegetable oils as corn, cottonseed, soybean, and coconut.'^ However, 

 it is present in hydrogenated vegetable fats. Grossfeld and Simmer^^ re- 

 port 1.49% of vaccenic acid in margarine, which is in the range of values 

 found by these authors for butter. It has been suggested that vaccenic 

 acid possesses growth-stimulating properties, ^^ but this hypothesis has 

 been shown by later work to be fallacious. ^^ "-'*■-'"' 



Bertram^* was of the opinion that natural vaccenic acid possesses a trans 

 configuration. This hj^pothesis has been shown to be correct, on the basis 

 of a recent study of Rao and Daubert.^^ 



c. Hexadecenoic Acid. Palmitoleic acid so named because of its 

 analogy to palmitic acid. It is found in marine animal oils in amounts of 

 lo to 20%, while the depot fats of amphibia and reptiles contain 8 to 15% of 

 this compound. The depot fats of birds are reported to have 6 to 8% of this 

 acid. Mammalian fats contain much less (liver fats 6-8%; depot fats 

 2-3%), while the vegetable oils have only a small proportion of the acitl 

 (usually less than 1%). Palmitoleic acid has also been shown to occur in 



" S. H. Bertram, Biochem. Z., 197, 433-441 (1928). 



'* J. Grossfeld and A. Simmer, Z. Uritersuch. Lebensm., 59, 237-258 (1930). 



i« R. P. Gever, H. Nuth, V. H. Barki, C. A. Elvehjem, and E. B. Hart, J. Biol. Chcnt., 

 169, 227-228 (1947). 



1' J. Boer, B. C. P. Jan.sen, and A. Kentie, Nature, 158, 201 (1946). 



i« H. J. Deuel, Jr., S. IM. Greenberg, E. Straub, D. Jue, C. M. Gooding, and C. F. 

 Brown, /. Nutrition, 35, 301-314 (1948). 



^' B. V. Euler, H. v. Euler, and G. Lindeman, Arkiv Kami Mineral. GeoL, B26, No. 3, 

 1-5 (March 19, 1948). 



20 H. Nath, V. H. Barki, C. A. Elvehjem, and E. B. Hart, /. Nutrition, 36 761-772 

 (1948). 



20" J. Boer, E. H. Groot, and B. C. P. Jansen, Voeding, 9, 60-62 (1948); Chem. Abst., 

 It2, 7847 (1948). 



21 P. C. Rao and B. F. Daubert, J. Am. Chem. Sac, 70 1102-1104 (1948). 



22 T. P. Hilditch and H. Jasperson, Biochem. J., 37, 238-243 (1943). 



23 J. B. Brown and B. M. Orians, Arch. Biochem., 9, 201-219 (1946). 



2^ R. W. Riemenschneider and N. R. Ellis, J. Biol. Chem., 114, 441-447 (1936). 

 ^5 T. P. Hilditch and M. L. Meara, Biochem. J., 38 29-34 (1944). 



