Figure 3:

(a) Modeled structural overview of Cas9-sgRNA-dsDNA system. (b) Fine-tuned HNH active site overview. Residues Asp839, His840, Asp861 and Asn863 are shown as stick and colored by element (C: green; N: blue; O: red). The first shell water molecule is shown as stick, and the nucleophilic water is shown as ball and stick. Mg2+ is shown as orange sphere. The nucleic acid is shown as stick and colored by element (C: blue; N: blue; O: red; P: orange). This figure is generated by PyMol.21