THE CYCLIC HELIX AND CYCLIC COIL FORMS OF POLYOMA VIRAL DNA.

The DNA extracted from polyoma virus exhibits certain properties which have not been reported for other viral base-paired DNA’s.1 The DNA renatures monomolecularly. The loss of helical configuration does not impair biological activity. Heating at 100° for 10–20 min followed by rapid cooling does not reduce the infective titer. Dulbecco has given evidence suggesting that a fraction of the polyoma DNA molecules are cyclic.2 This form would in part account for the above properties.

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