TRIGLYCERIDES AND FATTY ACIDS 113 



dase prepared from soj^bean used one mole of oxygen, while oxidation of lino- 

 lenic acid mider similar conditions required two molecules of O2. In con- 

 tradistinction to these results, only 0. 1 mole of O2 was utilized per mole of 

 oleic or ricinoleic acid. 



(d) Isolation of Pure Lipoxidase. Siillman"'^ prepared an acetone powder 

 of soybean lipoxidase. Cosby and Sumner-^^ effected a 1 :60 concentration 

 of the enzyme, while Balls, Axelrod, and Kies-'^ were able to prepare an 

 aqueous extract of soybean meal with a specific activity 115 times that of a 

 2.5% water extract of the meal. Theorell, Bergstrom, and Akeson"" re- 

 ported the preparation of an electrophoretically-homogeneous enzyme 

 which had an activity of 130 units per mg. ; later, an improved method of 

 preparation was reported. ^^^---^ Theorell, Holman, and Akeson"2.223 have 

 now prepared a crystalline lipoxidase from soybean flour, by precipitation 

 with ammonium sulfates, which is electrophoretically homogeneous at pH 

 6.0, and which is homogeneous to sedimentation and diffusion patterns. 

 The following properties are reported:--^ sedimentation constant, 5.62 X 

 10~^^- diffusion constant, 5.59 X 10"^; partial specific volume, 0.750; 

 and molecular weight, 102,000. The isoelectric point is at a pH of approxi- 

 mately 5.4. The absorption spectrum is that of a common protein with a 

 moderately high absorption at 280 m^. Lipoxidase is a colorless protein, 

 devoid of iron and containing no detectable prosthetic group. It is soluble 

 in dilute salt solution, but insoluble in water. ^^■^ The activity of the en- 

 zyme was found to be such that 330 moles of linoleic acid were oxidized per 

 mole per second under the conditions of the test. 2- ^ Holman and associ- 

 ates--^ reported that crystalline lipoxidase contains 938 amino acid residues 

 per molecule; the authors accounted for 94% of the composition of the 

 molecule. 



(e) Properties of Lipoxidase. The optimum pH for lipoxidase activity 

 has been reported as 9.4, with continued effectiveness at a high rate at a 

 pH--^ up to 11.7. However, Smith-^^ stated that the optimum pH of soy- 



217 H. Siillman, Helv. Chim. Acta, 26, 2253-2263 (1943). 



"18 E. L. Cosby and J. B. Sumner, Arch. Biochem., 8, 259-264 (1945). 



219 A. K. Balls, B. Axelrod, and M. \V. Kies, /. Biol. Chem., 149, 491-504 (1943). 



220 jj Theorell, S. Bergstr5m, and A. Akeson, Arkiv. Kemi, Mineral., Geol., 19 A, 

 No. 6, 1-9 (1944). 



"1 H. Theorell, S. Bergstrom, and A. Akeson, Pharm. Acta Helv., 21, 318-324 (1946); 

 also cited by S. Bergstrom and R. T. Holman, Advances in Enzymol., 8, 425-457 (1948), 

 p. 445. 



"2 H. Theorell, R. T. Holman, and A. Akeson, Arch. Biochem.., I4, 250-252 (1947). 



223 H. Theorell, R. T. Hoiman, and A. Akeson, Acta Chem. Scand., 1, 571-576 (1947). 



224 R. T. Holman, F. Panzer, B. S. Schweigert, and S. R. Ames, Arch. Biochem., 26, 

 199-204 (1950). 



225 R. T. Holman, Arch. Biochem., 15, 403-413 (1947). 



226 G. N. Smith, Arch. Biochem., 19, 133-143 (1948). 



