PnoTEiN Synthesis in Protoplasts 



191 



concerned, are clear-cut. It is quite evident from the data 

 summarized in Table II that considerable amounts of DNA 

 can be removed, up to 99 per cent, without loss of enzyme- 

 forming capacity. However, it will be noted that in those 

 cases where 30 per cent or more of the RNA is lost, serious 

 inhibitions of enzyme-forming ability resulted. 



Table II 



The Efect of DNAse on Enzyme Synthesis and DNA and RNA Content 



DNAse (400 [j.g./ml.) was present in the experimental flasks during proto- 

 plast formation (45 minutes). Protoplasts were then recovered by centrifuga- 

 tion and washed. An aliquot was used for determination of DNA, RNA and 

 protein. The extent of removal of each nucleic acid is determined in terms of 

 ratio to protein in the protoplast pellet and comparison with untreated control. 

 This corrects for loss due to lysis during treatment. Enzyme-forming ability 

 is examined with another ahquot of the protoplasts which is resuspended in an 

 induction mixture (0-5M-K2HPO4, pH 7-8; 2% amino acids, 0-6% hexose- 

 diphosphate, and, 0-06m lactose). Samples are removed periodically for 

 enzyme assay. Enzyme activity is determined in terms of the muM of o- 

 nitrophenyl-^-D-galactoside hydrolysed per mg. of protein per minute. The 

 rate of enzyme formation is obtained as the number of enzyme activity units 

 synthesized per mg. of protein per hour. 



Table III gives a comparable series of experiments in which 

 the protoplasts were treated with RNAse, and here the picture 

 is also clear. In most cases, there is relatively little con- 

 comitant loss in DNA. Again, one observes that wherever the 

 removal of RNA exceeds 35 per cent, drastic inhibitions of 

 enzyme-forming capacity results. 



The data obtained in the experiments just described support 



