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TRANSFORMATION OF PNEUMOCOCCAL TYPES 



extracts are rapidly inactivated at the low pH required for its use. Prolonged 

 treatment with crystalline ribonuclease under optimal conditions caused no 

 demonstrable decrease in transforming activity. The fact that trypsin, 

 chymotrypsin, and ribonuclease had no effect on the transforming principle is 

 further evidence that this substance is not ribonucleic acid or a protein suscep- 

 tible to the action of tryptic enzymes. 



In addition to the crystalline enzymes, sera and preparations of enzymes 

 obtained from the organs of various animals were tested to determine their 

 effect on transforming activity. Certain of these were found to be capable of 

 completely destroying biological activity. The various enzyme preparations 

 tested included highly active phosphatases obtained from rabbit bone by the 

 method of Martland and Robison (15) and from swine kidney as described by 



TABLE II 

 The Inactivation of Transforming Principle by Crude Enzyme Preparations 



H. and E. Albers (16). In addition, a preparation made from the intestinal 

 mucosa of dogs by Levene and Dillon (17) and containing a polynucleotidase 

 for thymus nucleic acid was used. Pneumococcal autolysates and a commer- 

 cial preparation of pancreatin were also tested. The alkaline phosphatase 

 activity of these preparations was determined by their action on /3-glycero- 

 phosphate and phenyl phosphate, and the esterase activity by their capacity 

 to split tributyrin. Since the highly purified transforming material isolated 

 from pneumococcal extracts was found to contain desoxyribonucleic acid, 

 these same enzymes were tested for depolymerase activity on known samples 

 of desoxyribonucleic acid isolated by Mirsky 3 from fish sperm and mammalian 

 tissues. The results are summarized in Table II in which the phosphatase, 

 esterase, and nucleodepolymerase activity of these enzymes is compared with 

 their capacity to destroy the transforming principle. Analysis of these results 

 shows that irrespective of the presence of phosphatase or esterase only those 



3 The authors express their thanks to Dr. A. E. Mirsky of the Hospital of The 

 Rockefeller Institute for these preparations of desoxyribonucleic acid. 



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