The maintainence of DNA methylation patterns by the Dnmt1 DNA Methyltransferase is essential for human cells. In a publicationin "FEBS Letters", a journal published by the Federation of European Biochemical Societies, we studied how Dnmt1 intacts with DNA by experimental investigation of the importance of individual atoms of the DNA for DNA recognition. Our results show that a large conformational change of the DNA, which is visible in the crystal structure of the Dnmt1-DNA complex, is not improtant for catalytic activity of Dnmt1. These unexepcted data underscore the importance of detailed biochemical studies to understand the molecular function of biomolecules.