Spin-stretching of DNA and protein molecules for detection by fluorescenceand atomic force microscopy

We have developed a rapid and efficient way of stretching DNA and denatured protein molecules for detection by fluorescence microscopy and atomic forc e microscopy (AFM). In the described method, a viscous drag created by a tr ansient rotational now stretches randomly coiled DNA molecules or denatured proteins. Stretching is achieved by dispensing a droplet of sample solutio n containing DNA or denatured protein on a MgCl2-soaked mica surface. We pr esent fluorescent images of straightened RDNA molecules and AFM images of s tress-sheared, reduced von Willebrand factor as well as straightened RDNA. The described quick and reliable spin-stretching technique will find wide a pplications in the analysis of single biopolymer molecules.