492 W. SCHAFER 



The elementary analysis of this type of preparations yielded the following 

 values: 33.7 % C; 15.3 % N; 0.57 % P; and 0.05 % Cu. A total of 2.8 % re- 

 ducing sugar was found. Most of this, as well as the phosphorus present, is 

 from nucleic acid, which comprises 5.6 % of the total. The major fraction of 

 this virus, amounting to '--' 89 %, is protein. About 5.7 % of the total 

 consists of lipid (Hoagland et al., 1940a,b, 1941a; see Smadel and Hoagland, 

 1942; see Hoagland, 1943). 



The nucleic acid of vaccinia virus, as well as that of papilloma virus, has 

 been demonstrated with some certainty to be exclusively DNA, but vaccinia 

 virus does not contain just one molecule of DNA of 4 x 10**. On the basis of 

 a particle weight of --^ 3.2 X 10^ it contains weU over 40 such DNA 

 molecules. Paper chromatographic analysis of the bases showed that there 

 is no uracil and that 5-hydroxymethylcytosine, present in the DNA of 

 several coliphages, cannot be detected in the nucleic acid of vaccinia virus 

 (Wyatt and Cohen, 1953). 



Detailed studies on the protein fraction, particularly as to its amino acid 

 composition, have not yet been carried out. 



The lipid fraction of the purified preparations is composed of 1.4 % 

 cholesterol, 2.2 % phospholipid, and 2.2 % neutral fat. Since the cholesterol 

 could be extracted by ether without imparmg the infectivity of such a virus 

 preparation, it was not considered an essential part of the uifective particles 

 (Hoagland et al., 1940b). But as Beard (1948) has previously mentioned, this 

 conclusion does not necessarily foUow from the particular experiment, since 

 the extracted cholesterol may have originated from previously denaturated 

 virus particles rather than from intact particles. Since only about 1.5 % of 

 the particles in the preparation studied were still infectious before the ether 

 treatment, this latter theory appears Ukely. 



Tightly bound to the virus particle is a riboflavin, which could be identified 

 as flavine-adenine dmucleotide (FAD) with the aid of the specific apoenzyme 

 of d-Simmo acid oxidase from pig kidney (Hoagland et al., 1941b). This com- 

 ponent could not be separated from the virus by electrodialysis, ultrafiltra- 

 tion, or by washing the virus particles with buffers ranging from pH 6 to 

 pH 8. The separation was possible only after denaturation of the virus 

 protein. Adsorption of extraneous FAD can be widely excluded since control 

 experiments showed that the virus particle does not take up additional 

 amomits of this coenzyme from dilute solutions (Hoagland et al., 1942). 

 Using microbiological assays with Lactobacillus casei E, it was shown that 

 100 gm. of highly purified virus material contains between 1.1 and 1.5 mg. 

 of riboflavin. 



Although this coenzyme is present, no dehydrogenase activity was de- 

 tectable. Further, neither cytochrome nor cytochromoxidase could be 

 detected by spectroscopic or biochemical methods. 



