EFFECTS OF SPERMINE ON THE RIBONUCLEOPROTEIN PARTICLES 25 1 



and Mg + + [23]. These findings are not in disagreement with the existence 

 within the particles of Mg ^ +-spermine-phosphate complexes. 



The finding that spermine could release the enzymes from the particles 

 without disrupting them prompted us to look for this polyamine in the 

 particles. We were encouraged by a report [24] that in E. coli and in liver 

 particles there exist some of these polyamines, namely putrescine, cadave- 

 rine, and spermidine. We have used the electrophoretic and chromato- 

 graphic methods mentioned [24] and have tentatively identified spermine 

 and perhaps spermidine in rat liver, guinea-pig liver, and guinea-pig 

 pancreas particles.* Contrary to the above, we could find no cadaverine 

 nor spermidine in the rat liver particles using the methods mentioned ; but 

 we also found another compound (cf. [24]) which gave a ninhydrin colour 

 and was positively charged, but whose mobility was different from that 

 of the polyamines mentioned and the basic amino acids. Thus, these 

 polyamines could well be the physiological agents which might effect a 

 release of synthesized enzymes, leaving the RNP structure intact. A 

 possible physiological mechanism regulating this release would thus have 

 to do with Mg + + availability and displacement by spermine. 



However, it could be that spermine acts in these particles as a stabiliz- 

 ing agent, helping to hold the particle together, as it has been found to 

 preserve nucleic acid structure [25, 26], to preserve bacterial [27, 28] 

 and protoplast [27, 29] structure, as well as conferring stability on mam- 

 malian mitochondria [29] and nuclei [20]. Also, it has been found that 

 these polyamines can bind strongly to polynucleotides [30] and to phage 

 [21], and thus to stabilize and neutralize the DNA of the latter [21]. 



There have been reports that the total proteins of the RNP particles 

 from liver [31, 32], reticulocytes [31] and pea seedlings [31] contain 

 relatively large amounts of basic amino acids, but other findings suggest 

 that this is not the case for E. coli particles [15], nor for liver particles [33]. 

 If this be the case, it is hard to see, from the discussion above, how these 

 basic amino acids contribute to the binding of the RNA to the protein, 

 particularly in light of the finding that even histidine does not bind 

 strongly to certain synthetic polynucleotides [30]. 



References 



1. Palade, G. E., and Siekevitz, V.,J. biophys. biochem. Cytol. 2, 671 (1956). 



2. Siekevitz, P., and Palade, G. E., ibid. 4, 203 (1958). 



3. Siekevitz, P., and Palade, G. E., ibid. 4, 309 (1958). 



4. Siekevitz, P., and Palade, G. E., ibid. 4, 557 (1958). 



5. Siekevitz, P., and Palade, G. E., ibid. 5, i (1959). 



* However, it is possible that in vivo the particles do not contain these poly- 

 amines, for their presence in the isolated particles may be a result of redistribution 

 during homogenization, from a soluble state to that of being bound to any available 

 phosphate groups of the RNA. 



