LYSOSOMES, A NliW GROUP OF CYTOPLASMIC PARTICLES I59 



Dr. df. Duve: This is very true. Isotope stiulics have revealed tlie higli turnover of 

 many cell constituents. There are two aspects, one anabolic, the other catabolic, to 

 turnover, and lysosomes might play a role in the latter. One could even consider a 

 limited degree of destruction as essential to keep the enzyme forming systems in func- 

 tional state. 



Dr. M.\rslan[): Is it necessary to invoke necrosis and other pathological states in 

 seeking a physiological role for the lysosomes? In perfectly normal cells could there not 

 be a use for 'scavenger' activity to rid the cell of such things as inactivated enzymes and 

 similar products resulting from the instability of normal cell components? 



Dr. he Duve: Indeed. Such activity might come under the heading of physiological 

 autolvsis. 



NOTE ADDED IN PROOF 



.'Additional information conccrninj; the lysosomal enzymes has come from several sources. 

 •According to in\ estimations h\ Rademaker and Soons (Rademaker, W. and ). B. I. Sooxs. 

 Biocliim. et biophys. acta 24: 451, 1057) and by Finkenstaedt (Finkenstaedt, I. T. Proc. 

 Soc. Exper. Biol. & Med. 95: 302, 1957) the catheptic activity of the particles may be due to 

 a mixture of cathepsins .\, B and C. The localization of phosphoprotcin phosphatase in the 

 lysosomes has been established (Paigen, K. and S. K. Griffiths. /. Biol. Chcm. 234: 299, 1959). 

 In our laboratory it has been shown (Sellinger, O. and A. D. Doyen. Arch. Inteniat. Physiol. 

 Biochem. In press) that /3-N-acetyl glucosaminidase is a lysosomal enzyme. With respect to 

 the physiopathological significance of lysosomes, attention is called to an interesting study 

 (Straus, W. /. Biophys. Biochem. Cytol. 4: 541, 1958) of the particles inxohed in the segre- 

 gation of an iniccted protein (peroxidase) called by the author 'phagosomes.' Direct evidence 

 that the release of lysosomal enzymes may play an important role in the involution of the 

 Mullcr ducts in chick embryos has recently been provided (Brachet, ]., M. Decrolv-Briers 

 AND J. HovEZ. Bull. Soc. Chilli. Biol. 40: 2039, 1958). The various unpublished observations 

 from our laboratory referred to in the present review are described in detail in a series of 

 papers which have been submitted for publication in the Biochemidil Joiinnil. 



