Simplified quantitative electron microscopy of biopolymers

Abstract

Abstract Shape and molecular weight of DNA can be obtained with a new method involving spontaneous surface adsorption of DNA or of other macromolecules from a solution which contains formaldehyde and a critical amount of cytochrome c. Subsequent transfer to specimen grids and electron microscopy shows individual molecules suitable for quantitative evaluation. Adsorption of DNA and fd bacteriophages is proportional to (time) 0.75 . Contour lengths of double‐stranded DNA are not influenced by formaldehyde. A modification of this method requires only 2 × 10 −5 μg DNA.