Abstract
Investigation of the protein compositions of highly purified preparation8 of eight strains of tobacco mosaic virus revealed that each strain possesses a characteristic composition which in several instances could be demonstrated to differ significantly from that of the other strains (1). The differences found consist mainly of altered proportions of certain amino acids, but it was also found that one of the strains, HR, contains two amino acids, histidine and methionine, apparently absent from the other strains examined, including common tobacco mosaic virus (TMV). It was concluded therefrom that mutation of tobacco mosaic virus can be accompanied by changes in the amino acid content of the virus. Since these strains of TMV are nucleoproteins, it is obvious that mutation in the virus might be associated with changes in the nucleic acid composition as well as with change8 in the protein composition. From previous results of phosphorus and pentose analyses (2), it would appear that all of the strains contain the same quantity and type of nucleic acid; namely, about 6 per cent of pentose nucleic acid. However, changes in the composition of the nucleic acid might occur during virus mutation without such change8 being reflected in the total amount of nucleic acid. In the present investigation, the molar proportions of the purine and pyrimidine bases in the nucleic acids were determined for the strains of tobacco mosaic virus on which the amino acid a88ays had previously been made. The results indicate that, with the exception of cucumber viruses 3 and 4, the strains contain the same proportions of purines and pyrimidines.
Highlights
The molar proportions of the purine and pyrimidine bases in the nucleic acids were determined for the strains of tobacco mosaic virus on which the amino acid a88ayshad previously been made
The results indicate that, with the exception of cucumber viruses 3 and 4, the strains contain the same proportions of purines and pyrimidines
The present results indicate that the nucleic acids of tobacco mosaic virus (TMV) strains may have identical compositions
Summary
ACIDS OF SOME STRAINS OF TOBACCO MOSAIC VIRUS The molar proportions of the purine and pyrimidine bases in the nucleic acids were determined for the strains of tobacco mosaic virus on which the amino acid a88ayshad previously been made. Definite amino acid spot,swere detected in the paper chromatography under conditions which should have rcvcalcd them, had there been 2 per cent of protein in the original nucleate preparation. ACIDS OF TOBACCO the pyrimidines mainly in the form of their nucleotides together with an almost negligible amount of nucleosides In chromatography of such hydrolysates of TMV and strain nucleates, only four spots were observed corresponding exactly with standard samples of adenine, guanine, cytidylic acid, and uridylic acid. Coefficients calculated from readings taken directly on the standard solutions without chromatography were very similar to those just listed, and all of them agree with the values used by Markham and Smith [6]
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