ANTI-ENZYME IMMUNITY 321 



Tests with pneumococcal hemolysin for proteolytic and phosphatase 

 activity were negative, and tests for lipolytic activity were stated to be 

 inconclusive. It did not cause detectable turbidity or a flocculation 

 when mixed with egg-yolk solution. Hemolytic activity was unaffected 

 after treatment with 0.05 M oxalate, citrate or fluoride. They stated 

 that all of their assays showed practically stoichiometric relations 

 between the amount of lysin and the number of cells, within the 

 titration range. 



On the basis of the above observed facts, the statement was made 

 that the action of the lysin upon the red cell, or upon the usual sub- 

 strates, thus far indicated that it possessed no enzymatic activity. 



It is possible to interpret the findings of these investigators in another 

 way, however. The observed stoichiometric relationship might be due 

 to a combination between a "cholesterol-like" inhibitor substance, 

 produced as one of the hemolytic reaction products, and the hemo- 

 lysin.* According to this hypothesis, the inhibitor is present in the 

 intact cell, but as part of the cell is ineffective to inhibit the lysin. 

 Its inhibitory action arises as a consequence of the rupture of the cell 

 by the hemolysin. The combination of such reaction products and the 

 catalyst is often irreversible and obeys the mass action law. For ex- 

 ample, /3-maltose as part of the starch molecule has no inhibitory ac- 

 tion on iS-amylase. However, following the hydrolysis of starch by 

 amylase, /8-maltose is liberated and only then exercises an inhibitory 

 action on amylase. The inhibition of pneumococcal hemolysin, fol- 



*In this connection the resuhs of a comprehensive study by Ponder (1946) on 

 the mechanism of the inhibition of non-enzymatic hemolysis by saponin, sodium 

 taurocholate, or sodium glycocholate might be of interest. He reported the following 

 observations : 



(1) The suspension medium of a thrice washed red cell suspension contains 

 inhibitory substances which render inert a small quantity of lysin, so far as the hemo- 

 lytic effect is concerned. 



(2) On the addition of the lysin to the cell suspension, a further quantity of lysin 

 is rendered non-hemolytic within the short time necessary for the separation of the 

 cells from the bulk phase of the system, and before any lysis takes place. This quan- 

 tity is several times greater than that found in (1). 



(3) The colorimetric measurements show that the quantity of chromogenic material 

 in the bulk phase, after contact with the cells, is substantially the same as that 

 present initially, and that no appreciable quantity of the lysin initially present accu- 

 mulates in increased concentration at the red cell surfaces. 



According to Ponder (1943) the inhibition of saponin lysis by plasma seems to 

 be somewhat as follows: About 35 per cent of the inhibition is due to cholesterol, 

 about 15-25 per cent to the globulins, and the rest to "enhancing effects," particularly 

 by lecithin on the cholesterol inhibition. The latter are very complex. 



