extensive homology stimulates the catenation of circular single-stranded dna and superhelical dna , whereas little reaction occurs between these forms of the closely related dnas of phages phi x174 and g4 , indicating that , in conjunction with topoisomerase i , reca protein can discriminate perfect or nearly perfect homology from a high degree of relatedness .
C0012935
single-stranded dna
C0012854
dnas