<p>Only the guanidinium group of Arg38 (in blue) is visible in this orientation. DNA is shown in grey. In this model the hydrogen bonds between the arginine guanidinium group and the minor groove of DNA are maintained, whereas the methyl group (in red) has an external position. In the side facing DNA there is no room for the methyl group, without disturbing the guanidinium-DNA hydrogen bonds.</p
