'DNA snapback' peptides.

Thermal denaturation studies show that 10-15% of the calf thymus DNA in the heat denatured (Tyr-Gly-Tyr-Gly-Tyr)-DNA complex renatures spontaneously after colling. The double-strandness of this DNA was verified by its resistance to single-strand Neurospora endonuclease and by its elution profile on hydroxypatite columns. The renatured DNA isolated by the latter technique was found to contain 56% GC compared to the 41% GC content of the whole thymus DNA. Alternating tryptophanyl-glycyl and histidyl-glycyl peptides also catalyze the same renaturation. A linear correlation was found between the thermal stabilization afforded to the DNA by the various peptides and their ability to "catalyze" DNA strand renaturation.