CHAPTER 10 



Isolation and Composition of the Deoxypentose Nucleic Acids 

 and of the Corresponding Nucleoproteins 



ERWIN CHARGAFF 



Page 



I. Introductory Remarks 308 



II. Deoxypentose Nucleoproteins 309 



1. General 309 



2. Classification 311 



3. Isolation 312 



a. Extraction with Solutions of Low Ionic Strength 313 



(1) Preparation of Calf Thymus Nucleohistone 313 



(2) Preparation of the Nucleoprotein of Avian Tubercle Bacilli . . 314 



b. Extraction with Strong Salt Solution 315 



(1) Preparation of the Nucleoprotamine of Trout Sperm 316 



4. Properties 317 



a. Some Chemical and Physical Characteristics 317 



b. Cleavage and Degradation 319 



c. Artifacts 319 



III. Isolation of Deoxypentose Nucleic Acids 321 



1. General 321 



2. Preparative Procedures 323 



a. Extraction with Strong Salt Solution, Deproteinization with Chloro- 

 form 323 



(1) Sodium Deoxyribonucleate of Calf Thymus 323 



(2) Sodium Deoxyribonucleate of Yeast 324 



b. Extraction with Strong Salt Solution, Deproteinization by Satura- 

 tion with Sodium Chloride 325 



(1) Sodium Deoxyribonucleate of Calf Thymus 325 



c. Extraction with Water 326 



(1) Sodium Deoxyribonucleate of Calf Thymus 326 



d. Extraction with the Aid of Anionic Detergents 327 



(1) Sodium Deoxyribonucleate of Calf Thymus 327 



e. Comparison of Different Isolation Procedures 328 



f. Miscellaneous Procedures and Applications 329 



g. Nucleic Acids of Microorganisms and Viruses 330 



h. Removal of Pentose Nucleic Acid and of Other Impurities .... 332 



IV. Properties of Deoxj'pentose Nucleic Acids 333 



1. Elementary Composition and Standards of Integrity 333 



2. Denaturation and Degradation 337 



V. Some Partial Degradation Products 340 



1. General 340 



2. Preferential Removal of Purines 341 



307 



