Atomic force and electron microscopy of high molecular weight circular DNA complexes with synthetic oligopeptide trivaline.

Abstract Intramolecular compact structures formed by high molecular weight circular superhelical DNA molecules due to interaction with synthetic oligopeptide trivaline (1) were studied by atomic force and electron microscopy. Three DNA preparations were used: plasmids pTbo1, pRX10 and cosmid 27877, with sizes 6120 bp, 10500 bp and 44890 bp respectively. Plasmid pTbo1 and pRX10 preparations along with monomers contained significant amount of dimers and trimers. Main structures in all preparations observed were compact particles, which coincide in their appearance and compaction coefficient (3,5–3,7) with triple rings described earlier. The size and structure characteristics of triple rings and other compact particles on atomic force images in general coincide with those obtained by EM (2). AFM (3) images allow to get additional information about the ultrastructural organization and arrangement of DNA fibers within the compact structures. Along with triple rings in pTbo1 and pRX10—TVP complexes significant ...