ISOLATION AND COMPOSITION OF DEOXYPENTOSE NUCLEIC ACIDS 337 



ribonucleate (similar to Preparation 2 in Table I) the following values were 

 found for approximately 0.1% solutions in 0.1 M phosphate buffer of pH 

 7.1: [a]f = +100° ± 10°; Hf(P) = +1350° ± 100°; [M]^?) = +420° 

 ± 25°. [a]D(P) is the specific rotation with respect to phosphorus, equaling 

 100 ar,/bc(P), in which h is the layer thickness and c(P) the phosphorus 

 concentration in grams per 100 cc. of solution. [M]o(P) is the atomic rota- 

 tion with respect to phosphorus, equaling 0.3098[a]3(P). These terms, and 

 the corresponding viscosity expression Tjap^P) denoting the specific vis- 

 cosity divided by the molarity of the solution with respect to P,'" were 

 adopted for the same reasons that led to the introduction of the term for 

 extinction e(P). 



The formation of insoluble deoxypentose nucleates by tervalent cations, 

 especially lanthanum, has often been investigated ;^*'^''"^''*'''^'"2 but there 

 is little information concerning other salts or metal complexes, nor do de- 

 tailed solubility studies of these compounds seem to have been carried out. 

 Complexes and precipitates with streptomycin have been described,'"''^* as 

 has also the interaction of deoxypentose nucleic acids with dyes.'^^'"^ 



The physical properties of the nucleic acids are outlined in Chapters 13 

 and 14. Estimates of the molecular weight of calf thymus deoxyribonucleic 

 acid vary, less with the specimen than with the method of determination, 

 from 820,0001^* to 7,700,000.1'^ Mention should be made here of investiga- 

 tions on the electron microscopy of sodium deoxyribonucleates.i*''-^^- 



2. Denaturation and Degradation 



A mild, but persistent, mistreatment of a protein leads to a state of 

 malaise known, vaguely, as denaturation. It is not astonishing that the 

 nucleic acids, especially the deoxypentose nucleic acids, which in the gradual 

 recognition of their complex properties have emulated the proteins in many 

 respects, have come also into this legacy. The decay of a macromolecule 

 of a specific and complicated structure will usually go through a number 

 of successive stages; the changes, almost imperceptible in the beginning, 

 multiply cumulatively, until the collapse makes itself known with almost 



'" E. Hammarsten, G. Hammarsten, and T. Teorell, Acta Med. Scand. 68, 219 (1928). 



•" K. G. Stern and M. A. Steinberg, Biochim. et Biophys. Ada 11, 553 (1953). 



'" S. S. Cohen, J. Biol. Chem. 168, 511 (1947). 



"* H. V. Euler and L. Heller, Arkiv. Kemi, Mineral. Geol. 26A, No. 14 (1948). 



17' L. F. Cavalieri and A. Angelos, J. Am. Chem. Soc. 72, 4686 (1950). 



"» L. F.^Cavalieri, A. Angelos, and M. E. Balis, J. Am. Chem. Soc. 73, 4902 (1951). 



»" J. L. Irvin and E. M. Irvin, J. Biol. Chem. 206, 39 (1954): 



"» R. Cecil and A. G. Ogston, J. Chem. Soc, 1948, 1382. 



1" M. E. Reichmann, R. Varin, and P. Doty, J. Am. Chem. Soc. 74, 3203 (1952). 



180 J. F. Scott, Biochim. et Biophys. Acta 2, 1 (1948). 



'?' R. C. Williams, Biochim. et Biophys. Acta 9, 237 (1952). 



'8« H. Kahler and B. J. Lloyd, Jr., Biochim. et Biophys. Acta 10, 355 (1953). 



