I30 



SUBCELLULAR PARTICLES 



INTACT PARTICLES 



ENZYMES BOUND 



LOW ACTIVITY 



rjO.Au 



SUBSTRATES 



LIPOPROTEIN 



WARING BLENDOR 

 HYPOTONIC MEDIA 

 ISOTONIC NaCI OR KCt 

 FREEZING AND THAWING 



LECITHINASE 

 PROTEOLYTIC ENZYMES 

 INCUBATION AT pH 5 , 37° 

 DETERGENTS , CCI^^ 



■PHOSPHATE ESTERS 



NUCLEIC ACIDS 



[proteins ] 



MUCOPOLYSACCHARIDES 



ENZYMES SOLUBLE 



INJURED PARTICLES 



GLUCURONIDES 

 ■SULPHATE ESTERS 



HIGH ACTIVITY 



Fig. I. Schematic representation of the lysosome concept. 



(2). For the other enzymes, total lack of activity has not been demonstrated 

 directly hut has been deduced from the fact that they show the same proportion 

 of latent activity as acid phosphatase. 



An obvious corollary of the enzymic inertia of intact particles is that the ac- 

 tivities actually observed in a preparation must be due to free enzymes, and 

 should therefore be recovered quantitatively in a high-speed supernatant of this 

 preparation. Such ideal behavior is never seen. In the first place, the assay con- 



