MUCOLYTIC ENZYMES 



zyme until, after incubation with the enzyme, llie/;H is raised to about 

 13, when visible lysis takes place, as in the case of S. muscae. There 

 are also instances of organisms which are killed without any visible 

 lysis even at high pH values, e. g., Bacillus mcgatherhwi (35). 



Lysozyme, in contrast to most antibiotic agents, acts not only 

 on living" but also on killed microorganisms, but in the latter case 

 generally to a lesser degree. For example, M. lysodeiklicus killed by 

 chilled neutral acetone is lysed almost to the same degree as are living 

 organisms by lysozyme, while organisms killed by acidified acetone, 

 by alcohol, or especially by autoclaving are lysed to a much smaller 

 degree. Visible clearing apparently is a poor, but convenient, method 

 for the estimation of lysozyme. 



The phenomenon of bacterial lysis, whether by lysozyme, 

 phage, or other lytic enzymes, obviously is complex. Under the 

 influence of lysozyme the susceptible organisms sw^ell to several times 

 their volume, the Gram stain becomes negative, uptake of oxygen 

 stops, and in the supernatant solution nonprotein. nitrogen, inorganic 

 phosphate, and reducing substances appear (31). U seems quite 

 ob\ ious that one enzyme cannot catalyze such dixcrse reactions. 



The mechanisni of lysozyme action may be explained in terms of 

 hydrolysis of a substance of mucoid nature which is contained in the 

 bacterial membrane. That this type of hydrolysis takes place was 

 demonstrated by the appearance of reducing substances when ly.sozyme 

 was incubated with carbohydrate fractions extracted from susceptible 

 organisms following alkaline hydrolysis. The carbohydrate obviously 

 is not a capsular substance which is easily given off into the surrounding 

 media as is the specific soluble substances of pneumococci. The 

 carbohydrate, at least in highly susceptible organisms, occurs in a 

 quantity of about 3 to 5%. 



The findings of the writer's laboratory have been confirmed by 

 Epstein and Chain (10) and by Pirie (35). The carbohydrate was 

 said by Epstein and Chain to contain both a ketohexose and an amino 

 sugar, evidence for the former being a positive SeliwanofT reaction in 

 the dialyzates after incubation with lysozyme. The SeliwanofT 

 reaction, however, is not given by the substrate of lysozyme, but by a 

 carbohydrate present in M. lysodeiktkits with which the preparations 

 of Epstein and Chain must have been contaminated. 



As isolated in this laboratory, the substrate of lysozyme is a 



