THE NATURE OF BLOOD LIPIDS 355 



he developed a mathematical treatment, based upon the law of mass action, 

 for the calculation of the binding of the hydrogen ions, which is probably 

 applicable to the estimation of the multiple binding of other ions where a 

 series of association constants are involved. More recently, Klotz 30 

 simplified these equations and made possible an evaluation of the role of 

 electrostatic factors in binding. This also affords a means for determining 

 the number of ions bound per protein molecule and for assessing the bond 

 energies. Although the results of Klotz concern the combination of cal- 

 cium ions with casein, they are apparently applicable to the fatty acid- 

 protein complexes. 8 



Changes in the electrophoretic mobility furnish another criterion of an- 

 ion-protein combinations. For example, Ballou, Boyer, and Luck 31 

 showed that the speed of migration of serum albumin, which had previously 

 been equilibrated with solutions of the sodium salts of the fatty acids, was 

 increased as the chain length of the acids became greater. Although this 

 evidence is highly suggestive, Luck 8 postulates that phosphate might also 

 increase the net negative charge of the serum albumin. This would offer 

 a possible explanation for the electrophoretic finding. 



The thermal stability of serum albumin solutions, as determined by the 

 so-called cloud-point technic, has been shown to be increased by fatty 

 acid anions. 32-35 The stability of the albumin solutions became greater as 

 the length of the fatty acid chains was increased. These results were sup- 

 ported by the demonstration of a similar protective effect which was also 

 augmented with the increasing chain length of the fatty acids when ultra- 

 filtration was the criterion employed. 32 This also applied when the stabili- 

 zation of serum albumin against urea denaturation, as followed by viscosim- 

 etry, was the property investigated. 36,37 



Other indirect evidence cited by Luck 8 includes the results of Davis and 

 Dubos, 38 who observed that the beneficial effect of serum albumin on the 

 growth of tubercle bacilli was due to fixation of the albumin by oleic acid 



30 1. M. Klotz, Arch. Biochem., 9, 109-117 (1946). 



31 G. A. Ballou, P. D. Boyer, and J. M. Luck, J. Biol. Chem., 159, 111-116 (1945). 



32 P. D. Boyer, G. A. Ballou, and J. M. Luck, J. Biol. Chem., 167, 407-424 (1947). 



33 G. A. Ballou, P. D. Boyer, J. M. Luck, and F. G. Lum, J. Clin. Invest., 23, 454-457 

 (1944). 



34 G. A. Ballou, P. D. Boyer, J. M. Luck, and F. G. Lum, J. Biol. Chem., 153, 589- 

 605 (1944). 



36 P. D. Boyer, F. G. Lum, G. A. Ballou, J. M. Luck, and R. G. Rice, J. Biol. Chem., 

 162, 181-198 (1946). 



36 P. D. Boyer, G. A. Ballou, and J. M. Luck, J. Biol. Chem., 162, 199-208 (1946). 



37 E. L. Duggan and J. M. Luck, /. Biol. Chem., 172, 205-220 (1948). 



38 B. D. Davis and R. J. Dubos, J. Exptl. Med., 86, 215-228 (1947). 



