OBSERVATION OF GEOMETRIC STRUCTURE OF COLLAGEN MOLECULES BY ATOMIC-FORCE MICROSCOPY

Atomic force microscopy was used to study the geometric structure of c ollagen fibrils and molecules of rat calcanean tendon tissues. The aut hors found that the diameter of the fibrils ranged from 124 to 170 nm, and their geometric form suggested a helical winding with spectral pe riod from 59.4 to 61.7 nm, close to the band dimensions reported by el ectron microscopy. At high magnification, the surface of these bands r evealed images that probably correspond to the almost crystalline arra y of collagen molecules, with the triple helix structure almost visibl e. The typical helix width is 1.43 nm, with main periods of 1.15 and 8 .03 nm, very close to the dimensions reported by X-ray diffraction.