Biopolym. Cell. 2002; 18(5):401-405.
Structure and Function of Biopolymers
Study of cruciform structure in supercoiled pUC8 plasmid DNA by atomic force microscopy and computer modelling
1, 2, 3Limansky A. P.
  1. Mechnikov Institute of Microbiology and Immunology AMS of Ukraine
    14, Pushkinska Str., Kharkiv, Ukraine, 61057
  2. Institute of Experimental and Clinical Veterinary Medicine, UAAS
    83, Pushkinska Str., Kharkov, Ukraine, 61023
  3. Department of Microbiology, Arizona State Univesity
    Tempe, AZ 85287-2701 USA


The cruciform structure in supercoiled pUCS plasmid DNA immobilized on aminomodified mica in buffer solution after sample drying was imaged by atomic force microscopy (APM). The cruciform structure was formed by 15 nucleotides inverted repeats as shown from AFM images of DNA. The computer modelling has revealed the cruciform structure to be formed by 11 nucleotides hairpins and 4 bases loops. Free energy of the hairpin was determined to be -17.8 kcal/mol.


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