Early Study Measures DNA Flexibility to Improve Gene-Cloning Methods

This 1985 paper by Legerski and colleagues, published in the Journal of Molecular Biology, is a work of molecular biophysics and enzymology, not a biological or skin-related study. It used an enzyme called T4 ligase, which joins DNA pieces together, to study how flexible double-stranded DNA is in solution.

Using electron microscopes to examine DNA molecules produced by cutting a bacterial plasmid (pBR322) with the enzyme EcoRI and rejoining the pieces, the researchers calculated a value called the "statistical segment length" — a measure of DNA stiffness — of about 1030 Angstroms, with a margin of roughly 116 Angstroms, at 12 degrees Celsius. They then used this number, together with an existing mathematical model (the Jacobson-Stockmayer theory), to predict how efficiently DNA pieces of different shapes and ends would join together inside a test tube.

The paper's practical output is a set of tables meant to help researchers design better cloning experiments with five different types of DNA vectors used in genetic engineering. As an abstract-only chemistry and physics paper, it says nothing about biological effects, disease, or any therapeutic use, and the findings apply strictly to the test-tube joining reactions studied.