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Atomic force microscopy analysis of intermediates in cobalt hexammine-induced DNA condensation.

Authors
  • Liu, D
  • Wang, C
  • Li, J
  • Lin, Z
  • Tan, Z
  • Bai, C
Type
Published Article
Journal
Journal of biomolecular structure & dynamics
Publication Date
Aug 01, 2000
Volume
18
Issue
1
Pages
1–9
Identifiers
PMID: 11021648
Source
Medline
License
Unknown

Abstract

The packaging pathway of cobalt hexammine-induced DNA condensation on the surface of mica was examined by varying the concentration of Co(NH3)6(3+) in a dilute DNA solution and visualizing the condensates by atomic force microscopy (AFM). Images reveal that cobalt hexammine-induced DNA condensation on mica involves well-defined structures. At 30 microM Co(NH3)6(3+), prolate ellipsoid condensates composed of relatively shorter rods with linkages between them are formed. At 80 microM Co(NH3)6(3+), the condensed features include toroids with average diameter of approximately 240 nm as well as U-shaped and rod-like condensates with nodular appearances. The results imply that the condensates, whether toroids, U-shaped or rod-like structures have similar intermediate state which includes relatively shorter rod-like segments. The average size of the condensed toroids after incubated at room temperature for 5 h (approximately 240 nm) is much larger than that incubated for 0.5 h (approximately 100 nm). The results indicate that the condensation of DNA by Co(NH3)6(3+) is a kinetic-controlled process.

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