To further characterize the structure of DBE-mediated cross-links between AGT and DNA, the investigators incubated calf thymus DNA with AGT in the presence of DBE. They treated the reaction products with trypsin or proteinase K to reduce the AGT to a simple peptide and then heated the sample to remove labile adducts. Based on prior work, the researchers hypothesized that reductive desulfurization using Raney nickel would successfully cleave the bond between the cysteine-145 sulfur atom of AGT and the ethylene bridge of the cross-link. This hypothesis proved to be correct, and the result was DNA bearing only an ethyl group at the adduct site. With the peptide no longer attached, routine treatment with nucleases and phosphatases readily reduced the DNA to individual nucleosides, which could easily be analyzed by mass spectrometry (Figure 4). The results indicated the presence of N6-ethyl-dA, N2-ethyl-dG, and O6-ethyl-dG (Figure 2).
CORRECTION: This misconception is based on the idea of falsification, philosopher Karl Popper's influential account of scientific justification, which suggests that all science can do is reject, or falsify, hypotheses that science cannot find evidence that one idea over others. Falsification was a popular philosophical doctrine especially with scientists but it was soon recognized that falsification wasn't a very complete or accurate picture of how scientific knowledge is built. In science, ideas can never be completely proved or completely disproved. Instead, science accepts or rejects ideas based on supporting and refuting evidence, and may revise those conclusions if warranted by new evidence or perspectives.
Statistical hypothesis testing - Wikipedia
CORRECTION: This misconception likely stems from introductory science labs, with their emphasis on getting the "right" answer and with congratulations handed out for having the "correct" hypothesis all along. In fact, science gains as much from figuring out which hypotheses are likely to be wrong as it does from figuring out which are supported by the evidence. Scientists may have personal favorite hypotheses, but they strive to consider multiple hypotheses and be unbiased when evaluating them against the evidence. A scientist who finds evidence contradicting a favorite hypothesis may be surprised and probably disappointed, but can rest easy knowing that he or she has made a valuable contribution to science.