Protein Constituents of Spermatozoa 99 



acid from the nuclear protein, Miescher treated the Hpid-free 

 material first with cold mineral acid (e.g. 0-25-0-5°/o hydrochloric 

 acid) to remove the protein, and then with sodium hydroxide 'until 

 the mixture tasted distinctly caustic to the tongue', to extract nucleic 

 acid from the residue. 



The deoxyribonucleoproteins in the spermatozoa of a great many 

 fishes, including salmon, belong to the group of micleoprotamines 

 which can be extracted from the sperm nuclei with salt solutions. A 

 convenient method for such an extraction and purification has been 

 described by Pollister and Mirsky (1946). Spermatozoa of the brown 

 trout, Salmo fario, were 'homogenized' with 1m solution of sodium 

 chloride in a Waring mixer and the very viscous extract poured into 

 six volumes of water; this caused the precipitation of the nucleo- 

 protamine in the form of long strands, so fibrous that they could 

 be wound around a glass rod and transferred in this way to another 

 container. The fibrous material was dissolved in M-NaCl and re- 

 precipitated with water, and then washed successively with 65% 

 ethanol, hot 95% ethanol, and finally with ether; at this stage it 

 contained about 6% phosphorus and 18% nitrogen, and consisted 

 of deoxyribonucleic acid and protamine in a 6 : 4 ratio. When this 

 material was dissolved in M-NaCl and dialysed against M-NaCl, the 

 protamine slowly passed through the cellophane membrane leaving 

 behind the solution of deoxyribonucleic acid. On pouring this solu- 

 tion into five volumes of ethanol, a fibrous precipitate of the nucleic 

 acid was obtained, which, after drying, had a content of 8-97% 

 phosphorus and 14-47% nitrogen. This composition approaches 

 the theoretical value for the sodium salt of deoxyribonucleic acid, 

 9-28% phosphorus and 15-58% nitrogen. 



The removal of protamine from nucleoprotamine solutions in- 

 duces no significant change in viscosity. The high viscosity of nucleo- 

 protamine solutions is due entirely to the highly polymerized nucleic 

 acid. Deoxyribonucleic acid prepared, for instance, from herring 

 spermatozoa, has a molecular weight of 800,000; each molecule of 

 it requires some 100 molecules of protamine to form a molecule 

 of nucleoprotamine. According to some calculations by Felix (1952), 

 a single fish sperm nucleus contains 4-5x10^ nucleoprotamine 

 molecules, enough to provide about 190,000 molecules per each 

 chromosome, or several thousand per each gene. 



