42 Philip Siekevitz 



Table VII 



Release of amylase activity from microsomal nucleoprotein 

 particles 



The particles were detached from microsomes from 200 mg. guinea pig 

 pancreas. Incubated in 0-44 m sucrose with additions (total volume: 2 ml.) 

 for 30 min. at 35°C ; 8 ml. water then added and spun at 105,000 g for 90 min. 

 Amylase activity tested in resultant pellet and medium. 



Per cent amylase activity 



Data taken from Siekevitz and Palade (unpublished). 



does not do anything at all but when we combine Mg2+ 

 with ATP we obtained an inhibition of the releasing effect of 

 ATP alone. It appears that the added ATP or pyrophosphate 

 is complexing the Mg2+ in the particles, and this Mg2+ is 

 necessary in keeping the enzymes onto the particles. But 

 this is not the entire story. As Table VIII indicates, the 

 particles treated with ATP or with pyrophosphate lose most 

 of their RNA and only little of their protein. The RNA goes 



Table VIII 

 Release of RNA from microsomal nucleoprotein particles 



The particles were detached from the microsomes from 1 g. guinea pig 

 pancreas. Incubated in water or in 4 (xm ATP/2 ml. for 30 min. at 35°C; 

 8-0 ml. water was then added, and spun at 105,000 g for 90 min. RNA and 

 protein were determined in resultant pellet and medium. 



[ig. RNA yig. Protein 



Treatment In pellet In medium In pellet In medium 

 None 384 10 757 91 



ATP 74 15 666 176 



Data taken from Siekevitz and Palade (unpublished). 



