Human Topoisomerase Ⅰ, Tubulin And DNA Studied By Atomic Force Microscopy

1,Imaging and Studying Human TopoisomeraseⅠon Mica Surfaces in Air and in Liquid by Atomic Force McroscopyThe topography of human topoisomeraseⅠ(TOPOI) on mica surfaces in air and in liquid has been studied by atomic force microscopy (AFM). After adsorption of the low concentration (0.3U/μl) TOPOI on mica surfaces for 2 hours, and then imaged in liquid and in air by AFM, well-separated single TOPOI was observed. The comparison of the results between scanning in liquid and in air was done, the sizes of TOPOI scanned in liquid and in air were different. After adsorption of the high concentration (4U/μl) TOPOI on mica surfaces for 1.5 hours, TOPOI monolayer can be formed.The produced TOPOI monolayer on mica was flat and exhibited good stability.2,Imaging Human TopoisomeraseⅠcombined with DNA on Mica Surfaces by Atomic Force MicroscopyDivalent cation Ni2+ has been used to immobilize the DNA molecules. The topography of DNA molecules has been observed by AFM. When using high DNA concentration for AFM imaging, DNA networks and DNA molecule films can be formed. After topoisomeraseⅠcombined with DNA, TOPOI and DNA can both absorbed on mica surfaces.3,Studies of the Tubulin PolymerizationThe tubulin polymerization has been studied by atomic force microscopy (AFM) and UV. The topography of microtubule absorbed on APTES-mica surfaces has been observed by AFM in liquid. The kinetic curves of the tubulin polymerization have been detected by UV.4,Imaging and Studying DNA on HOPG by Atomic Force MicroscopyThe adsorption of Humic acid on HOPG surfaces has been studied by Atomic Force Microscopy(AFM) and Fourier transform infrared spectrometer(FTIR).After the detection of FTIR, Humic acid has definitely adsorbed on HOPG surfaces.The topographies of Humic acid, HA in the acidic or alkaline conditions and the admixture of HA and salt on HOPG surfaces have been studied by AFM. The influences of salt and acidic or alkaline conditions have been studied. HA molecular film can be formed on HOPG surfaces. As a template, DNA molecule can be adsorbed on humic acid film. The DNA absorbed on HA molecular film has been observed by AFM.