9604566 Hansma This research on atomic force microscopy (AFM) of biomaterials is being carried out on two classes of biomaterials: 1) DNA and DNA-protein complexes, and 2) Synaptic vesicles. More specifically, 1) the research on DNA and DNA protein complexes includes: a) unzipping DNA--pulling apart the 2 strands of the double helix in such a way that the base pairs have the possibility of separating one by one, and, b) imaging individual enzyme molecules in action on DNA. The first enzyme to be imaged in action on DNA will be E. coli RNA polymerase (RNAP), because it is active even when bound to a hard surface. The template for this enzyme will be a 42-base circular DNA molecule, because it replicates continuously, so that active enzyme molecules can be imaged for several minutes or more with the AFM. 2) For the research on synaptic vesicles, synaptic vesicles from the electric organ of Torpedo californica and from rat brain will be probed by imaging and force mapping in aqueous buffer and by phase mode imaging in air to investigate vesicle fusion, to measure the elasticities of the vesicles (Young's Moduli) and to probe the adhesive properties of the inner and outer surfaces of the vesicle membranes. The main objective of this research is to extend the capabilities of the atomic force microscopy (AFM) and probing biomaterials. The research on imaging enzyme molecules in action on DNA will yield information about the motion of individual enzyme molecules in the presence and absence of a substrate. The research on unzipping DNA will provide valuable information about the forces between the two strands of DNA. It is possible that sequence-specific information about DNA can be obtained in this way. The ability to visualize and probe individual synaptic vesicles in physiological solutions will complement the genetic and biochemical advances that have been made in this field. The AFM is just beginning to realize its potential as a valuable tool for biological research. This research also educates students in the use of the AFM, a new microscope that is becoming increasingly useful.
