ENZYMES CONCERNED WITH DIGESTION OF LIPIDS 25 



ture is 25 to 35°C. The enzyme is described as a specific phosphodiester- 

 ase ; it is not identical with glycerophosphatase. 



(d) Lecithinase D. This enzyme is a glycerophosphatase which acts on 

 the ester linkage between phosphoric acid and glycerol. The end-products 

 are phosphoryl choline and a diglyceride. The enzyme was discovered by 

 Macfarlane and Knight in 1941 in Clostridium welchii 152 (gas bacillus). 

 A similar enzyme has been reported in Clostridium edematis {oede?natiens) xhi 

 (isolated from war wounds), and in CI. hemolyticum toxin (hemolytic an- 

 aerobe found in the blood and tissues of cattle), 154 by Macfarlane, and in 

 CI. bifermentans lbb by Lewis and Macfarlane. 



Hemolysis of the red cells of horse and sheep blood by toxins of CI. 

 welchii and CI. oedematiens was always preceded, according to Macfarlane, 156 

 by decomposition of some of the phospholipids in the cells. Hemolysis, 

 therefore, is to be attributed to the action of the lecithinases present in the 

 toxin. The rates of hydrolysis of the phospholipids in intact erythrocytes 

 by lecithinases from different sources vary. Three immunologically 

 distinct lecithinases D are the CI. welchii a-toxin, the CI. oedematiens 

 7-toxin, and the CI. oedematiens /3-toxin. 156 Zamecnik et al. 157 found that the 

 injection of the purified total lipids obtained from erythrocytes, plasma, 

 and liver had a protective effect against CI. welchii toxin in mice and dogs. 

 It is suggested that the lecithin in the injected lipids protects the lecithin 

 present in the animal from destruction by the lecithinase D. 157 



Although the lecithinase D preparations do not decompose cephalin, 

 Macfarlane 158 showed that sphingomyelin was slowly destroyed by this 

 agent. Hydrolysis of the latter proceeds more slowly than that of lecithin; 

 like the hydrolysis of lecithin, that of sphingomyelin is activated by Ca and 

 inhibited by NaF. The end-products of sphingomyelin hydrolysis were 

 found to be phosphorylcholine together with a P-free product approaching 

 the composition of lignocerylsphingosine. 



Considerable work has been done on the undifferentiated lecithinases, in 

 which the production of soluble phosphate is employed as an index of their 

 activity. 159,160 King 159 reported that these enzymes were widely distri- 



152 M. G. Macfarlane and B. C. J. G. Knight, Biochem. J., 35, 884-902 (1941). 



163 M. G. Macfarlane, Biochem. J., 42, 590-595 (1945). 



1M M. G. Macfarlane, Biochem. J., 47, 267-270 (1950). 



165 G. M. Lewis and M. G. Macfarlane, Biochem. J., 54, 138-142 (1953). 



158 M. G. Macfarlane, Biochem. J., 47, 270-278 (1950). 



157 P. C. Zamecnik, J. Folch, and L. Brewster, Proc. Soc. Exptl. Biol. Med., 60, 33-39 

 (1945). 



158 M. G. Macfarlane, Biochem. J., 42, 587-590 (1948). 



159 E. J. King, Biochem. ./., 25, 799-811 (1931). 



160 E. J. King, Biochem. J., 28, 476-481 (1934). 



