I have recently read that Erwin Chargaff has discovered that the genome of phage phiX174 (ϕχ174) is single-stranded. However I could not find the paper reporting this discovery.

Is there a link to the paper reporting this finding?

Thank you.

  • $\begingroup$ can you give the citation, quote, or other paper trail for us to follow? Finding old papers can be difficult, and it isn't clear even whether Chargaff made that finding or merely if his work informed the discovery. I cannot find any meaningful association of him to the phage, though I also can't find an obvious paper or reference on pubmed that points to the discovery. Knowing what your starting point is would help. $\endgroup$ Feb 17 at 18:01

2 Answers 2


I think @MaximilianPress was close. Chargaff certainly did early work on DNA structure, but he was not the one to identify that the genome of φX174 was circular. As far as I can tell, the actual peer reviewed publication was a pair of papers in Journal of Molecular Biology, written by R.L. Sinsheimer in 1959. I can access these articles through my institution, but I suspect that they are paywalled.

These two articles are in volume 1, issue 1 of the journal on pages 37-42 and 43-53 respectively. I've reproduced the citations with abstracts below. The first indicates some oddities in the DNA of the bacteriophage and the second confirms these oddities and provides the explanation (emphasis is mine to highlight the salient point).

Robert L. Sinsheimer, Purification and properties of bacteriophage φX174, Journal of Molecular Biology, Volume 1, Issue 1, 1959, Pages 37-IN5, ISSN 0022-2836, https://doi.org/10.1016/S0022-2836(59)80005-X. (https://www.sciencedirect.com/science/article/pii/S002228365980005X)

Abstract: Procedures are described for the isolation in pure form of the bacterial virus φX174. This virus is shown to have a particle weight of 6·2 × 106 and to contain 25% by weight of DNA. At neutral pH, the purified virus forms a discrete aggregate, probably a tetra-mer. This aggregate dissociates either upon dilution or at alkaline pH. Lysates produced by φX174 contain a second particle, antigenically related to the virus, but not infective and of lower sedimentation rate and lesser DNA content. The DNA of φX174 appears to have an unusual structure in that it reacts with formaldehyde (even before extraction from the virus) and in that the atomic efficiency of inactivation of the virus by decay of incorporated phosphorus-32, calculated by combining our data and that of Tessman, is 1·0.

Robert L. Sinsheimer, A single-stranded deoxyribonucleic acid from bacteriophage φX174, Journal of Molecular Biology, Volume 1, Issue 1, 1959, Pages 43-IN6, ISSN 0022-2836, https://doi.org/10.1016/S0022-2836(59)80006-1. (https://www.sciencedirect.com/science/article/pii/S0022283659800061)

Abstract: The deoxyribonucleic acid (DNA) of bacteriophage φX174 can be extracted by phenolic denaturation of the virus protein. The DNA thus obtained has a molecular weight of 1·7 × 106, indicating that there is one molecule per virus particle. This φX DNA does not have a complementary nucleotide composition. The ultraviolet absorption of this DNA is strongly dependent upon temperature in the range 20° to 60°C, and upon NaCl concentration in the range 10−3 to 10° M. This DNA reacts with formaldehyde at 37°C and is precipitated by plumbous ions. This evidence is interpreted to mean that the purine and pyrimidine rings are not involved in a tightly hydrogen-bonded complementary structure. Light scattering studies indicate that this DNA is highly flexible and that its configuration is strongly dependent upon the ionic strength of the solution. Upon treatment with pancreatic deoxyribonuclease, the weight-average molecular weight decreases in accordance with the function expected for a single-stranded molecule. It is concluded that the DNA of bacteriophage φX174 is single-stranded.

  • $\begingroup$ well done! this definitely the right answer. Somehow I got the author/date right but clicked on the wrong article? $\endgroup$ Feb 20 at 19:55
  • 1
    $\begingroup$ @MaximilianPress Thanks. Took a bit of digging to find them because they apparently aren't indexed on Pubmed - it only comes up with the symposium you found, which is odd as J Mol Biol isn't exactly an unknown journal with no publishing history. $\endgroup$
    – bob1
    Feb 20 at 20:09
  • $\begingroup$ yeah, that must be what happened to me! And then when I saw author-date matching in the reviews I assumed it was the same. I also think that the "cited by" PubMed feature got confused for similar reasons, and linked me out to the papers citing the right (JMB) paper by accident! What a tangled web we weave. $\endgroup$ Feb 20 at 21:05
  • $\begingroup$ Thank you. Sorry but I did not have much quotes to report. $\endgroup$
    – Gigiux
    Feb 28 at 16:20


please see @bob1's answer below.

Original answer

I suspect that this is the paper you are interested in but I can't find even an abstract of it due to the obscurity/loss of the journal.

In a different review paper, this 1959 Sinsheimer paper is described as such:

The first DNA molecule purified to homogeneity was the genome of bacteriophage ϕX174, reported by Sinsheimer in 1959 (12). Equilibrium buoyant density centrifugation of the ϕX virion yielded pure preparations from which the DNA could be easily isolated by phenol extraction. ϕX DNA turned out to be a single-stranded circular molecule that was estimated to be ∼5000 nt in length.

  • $\begingroup$ It’s not a journal but a symposium volume. Most big university libraries would have it secreted in the bowels of their archives. I’ll see if ours has it, just for fun. $\endgroup$
    – David
    Feb 17 at 23:00
  • $\begingroup$ @David thank you! that would be wonderful. $\endgroup$ Feb 17 at 23:19
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    $\begingroup$ I've found it in Google Books at books.google.co.uk/… If anyone has difficulty with this link I've taken screenshots and can mount a pdf on one of my websites. Chargaff wasn't present at that symposium, according to the list of participants at the end. I think the poster has probably got hold of the wrong end of the stick. Chargaff was interested in this because its base composition violated the so-called Chargaff Rule. However we now know that this reflects the base-pairing in dsDNA. I can post an answer if useful. $\endgroup$
    – David
    Feb 18 at 18:00

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