310 



Mr. A. Fleming. On a Remarkable 



Observations on the Properties of the Lysozyme and on the 

 Conditions Governing its Action. 



The lysozyme is soluble in water or normal salt solution ; it is insoluble 

 in chloroform, ether or toluol, and, as these substances do not destroy it or 

 inhibit its action, they have been used to preserve lysozyme-containing 

 material such as sputum for test purposes ; it retains its potency undi- 

 minished after standing at room temperature for several weeks. That 

 lysozyme of egg white is not destroyed by desiccation, and that in the 

 dried state it can be preserved for long periods, is shown by the fact that it 

 is present in large amounts in commercial dried egg albumin. 



From albuminous fluids, protein precipitants such as alcohol, acetone, or 

 picric acid, precipitate the whole of the lysozyme with the proteids. 



Its action takes place most rapidly when a small amount of salt is present 

 in the fluid (under 01 per cent.), and ceases when more than 5 per cent, of 

 salt is present. It acts both on living microbes and on those which have been 

 killed with heat. 



Influence of the Reaction of the Fluid. 



It was found that when one drop of sputum extract and one drop of a thick 

 suspension of M. lysodeikticus were added to 1 c.c. of various dilutions of 

 hydrochloric acid or caustic soda, the lytic action was, to some extent, 

 delayed in the tubes containing as little as 1/8,000 normal acid or 1/24,000 

 normal alkali, and there was complete inhibition of lysis in the tubes 

 containing 1/800 normal acid or alkali. These figures are not strictly 

 accurate, as alkali-free glass was not used, but they clearly indicate that 

 the lysozyme is very sensitive to minute traces of acid or alkali. 



Resistance of the Lysozyme to Heat. 



Sputum extract, nasal mucus, saliva and subcutaneous fatty tissue, heated 

 for 10 minutes at 60° C, had lost but little of their lytic power for bacteria, 

 but 5 minutes' heat at 75° C. destroyed almost all the lysozyme. Tears, 

 diluted 500 times with normal saline solution, were heated for 10 minutes at 

 75° C, and the lysozyme-content was reduced to one quarter. After 

 boiling this dilution of tears for 30 minutes, traces of lysozyme remained 

 active, but boiling for 1 hour apparently completely destroyed it. 



In saliva, the resistance to heat of the lysozyme and of ptyalin was 

 compared. A specimen of saliva was heated to 75° C, and specimens were 

 taken at intervals of 1 minute, and their lysozyme and ptyalin-content 

 were compared. It was found that these two substances disappeared from 

 the saliva at the same time, namely, after heating for 7£ minutes. 



