66 BIOLOGY OF PNEUMOCOCCUS 



lyze under alternate freezing and thawing in phosphate solutions 

 with a reaction of pH 6.2, or by filtering sterile broth cultures, the 

 authors obtained cell-free extracts capable of hydrolyzing casein 

 and fibrin but not albumin and gelatin. The extracts digested pro- 

 teoses and peptones even more rapidly, converting them into pep- 

 tides and amino acids. The enzyme or enzymes were designated by 

 the authors as protease and peptonase, although it was stated that 

 these names might merely represent different activities of the same 

 ferment. The activity of the enzyme was favored by a reaction 

 of pH 7.0 to 7.8, but was suspended at pH 5.0. The enzyme, 

 however, was not destroyed by relatively short exposure to this 

 acid reaction, since its activity was restored when the pH of the 

 solution was readjusted to 7.8. The rapidity of hydrolysis was 

 proportional to the concentration of enzyme. Heating diminished 

 the digestive action, which was lost after ten minutes' exposure to 

 100°. The ability of active extracts to digest the protein of heat- 

 killed pneumococci was later shown by Goebel and Avery 520 by 

 demonstrating an increase in the non-coagulable and amino nitro- 

 gen after contact of the extract with the killed cocci. 



LIPOLYSIS 



The presence of an esterase in the pneumococcal cell has also 

 been demonstrated by Avery and Cullen. 39 Extracts of pneumo- 

 cocci, prepared in the manner employed for obtaining proteases, 

 split tributyrin. Heating for ten minutes at 70° destroyed the 

 activity of the lipase. While bile and bile-salts accelerated lipoly- 

 sis, they were not essential to the reaction, since pneumococcal ex- 

 tracts prepared in other ways exhibited the same enzymatic ac- 

 tivity. In the study of Goebel and Avery it appeared that on the 

 addition of extracts containing the active intracellular enzymes of 

 the pneumococcal cell to the ether-soluble lipids of pneumococci, 

 an increase in ether-soluble fatty acid occurred. Falk and Mc- 

 Guire 386 recently reported that strains of Pneumococcus, Types I 

 and II, in suitable broth, hydrolyzed phenylacetate, glyceryl tri- 



