CAROTENOIDS 



Sumner 23 « does not accept the view that the fat peroxides, pro- 

 duced as intermediates in the oxidation of the unsaturated fatty acids, 

 oxidize the carotenoids, for he found that oxidation by fatty acid 

 peroxides does not take place in the absence of the enzyme. He takes 

 the view that to effect oxidation of carotenoids the enzymic peroxidation 

 of the fat must actually be in progress. Oxidation is thus probably the 

 result of transfer of oxygen from an unstable intermediate formed during 

 the oxidation of the unsaturated fat, for in the presence of carotene 

 the rate of fat peroxidation is diminished. Extending this work 

 Holman23' found that the conjugated dienes, produced during the 

 oxidation of unsaturated fatty acids 2 3 s, 2 3 9 ^re reduced in the presence 

 of carotenoids, and he thus considers that the oxidation of these pig- 

 ments is a consequence of their interruption of the chain of reactions 

 by which the unsaturated fats are oxidized. A full discussion of the 

 whole problem is given by Bergstrom and Holman. ^ * ® 



Kies^*^ has recently isolated a crystalline polypeptide from Soya 

 beans which activates lipoxidase ; a very similar compound also occurs 

 in gum arabic. 



A number of methods for determining lipoxidase activity have been 

 devised ; 2 2 5, 2 2 7, 2 4 2- 2 4 4 t^gy ^j-g based on the measurement of the 

 rate of destruction of carotene under standard conditions and are 

 effective only within rather narrow limits. In legume seeds the level 

 of activity varies from 1-9 ** units " in Lima beans to 60 " units " in 

 Mandalay Soya beans. ^^^ Lipoxidase has recently been crystallized ^ * » 

 and analysed for its constituent amino-acids. ^ * « 



REFERENCES 



1. Weinzinger, F. (1940), Bull. Soc. Botan. Genive, 30, 130. 



2. Berzelius, J. J. (1837), Liebig's Ann., 21, 257, 



3. WillstAtter, R., and MiEG, W. (1907), Liebig's Ann., 355, 1. 



4. Karrer, p., and Widmer, R. (1928), Helv. Chint. Acta, 11, 751. 



5. Karrer, P., Helfenstein, A., and Widmer, R. (1928), Helv. Chint. Acta, 11, 1201. 



6. KuHN, R., Winterstein, a., and Weigand, W. (1928), Helv. Chim. Acta, 11, 716. 



7. WillstAtter, R., Meyer, E. W., and Huni, E. (1910), Liebig's Ann., 378, 73. 



8. Deuel, H. J., jun., and Morehouse, M. G. (1946), Advances in Carbohydrate Chemistry, 



2, 120. 



9. Smedley, I. (1911), y. Chem. Soc, 99, 1627. 



10. KuHN, R., Grunumann, C, and Trischmann, H. (1937), Hoppe-Seyl. Z., 284, iv. 



11. Bonner, J. (1948), J. Chem. Ed., 26, 628. 



12. Bonner, J., and Arreguin, B. (1949), Arch. Biochem., 21, 109. 



13. Arreguin, B., and Bonner, J. (1950), Arch. Biochem., 26, 199. 



14. Went, F. W., Le Rosen, A., and Zechmeister, L. (1942), Plant physioL, 17, 91. 



15. Hunter, R. F., and Scott, A. D. (1944), Biochem. J., 38, 211. 



16. Isler, O., Huber, W., Ronco, A., and Kofler, M. (1947), Helv. Chim. Acta., 30, 1911. 



17. Barrenscheen, H. K., Pany, J., and Srb, E. (1942), Biochem. Z., 310, 285. 



18. Holman, R. T. (1948), Arch. Biochem., 17, 459. 



19. Wai, K. N. T., Bishop, J. C, Mack, P. B., and Cotton, R. H. (1947), Plant PhysioL, 



22, 117. 



20. De, N. K. (1937), Ind. J. Med. Res., 24, 737. 



20a. Chattopadhyay, H., and Banerjee, S. (1951), Science, 113, 600. 



21. Beck, W. A., and Schroeder, M. P. (1938), Stud. Inst. Divi. Thomae, 2, 101. 



22. Miller, E. V., and Jablonski, J. R. (1949), Food Res., 14, 492. 



23. Beck, W. A. (1937), Protoplasma, 28, 273. 



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