Electrostatic surface comparison between AA9 and AA10 lytic polysaccharide monooxygenases. The images show the protein surface containing the active site as presented to the substrate. The yellow circles indicate the location of the catalytic residues and bound Cu2+. (a) The AA9 family has a strip of positively charged surface sandwiched in an overall negatively charged surface (shown in red). (b) In the AA10 family, a patch of positively charged surface (shown in blue) is adjacent to the active site. (c) Superposition and inset showing the active site residues of AA9 from Hypocrea jecorina (pdb id: 2VTC), Thielavia terrestris (pdb id: 3EII), Thermoascus aurantiacus (pdb id: 3ZUD), and Neurospora crassa (pdb id: 4EIS and 4EIR) in ribbon representation and colored with respect to secondary structure (helix-red; strand-yellow; loop-green). The residues involved in the active site are shown as sticks and colored blue for H. jecorina, magenta for T. terrestris, orange for T. aurantiacus, and light brown and gray for N. crassa. The divalent metal atoms (Ni, Zn, Cu) are shown as spheres. The active site residues labeled in the inset are colored the same as the intact structures. (d) Superposition and inset showing the active site residues of AA10 from Serratia marcescens (pdb id: 2BEM), Vibrio cholerae (pdb id: 2XWX), Burkholderia pseudomallei (pdb id: 3UAM), and Enterococcus faecalis (pdb id: 4A02) shown in ribbon representation and colored with respect to secondary structure. The residues (inset) involved in the active site are shown as sticks and colored green for S. marcescens, blue for V. cholerae, magenta for B. pseudomallei, and orange for E. faecalis.