Fig. 10

This shows some unusual H-bonding with respect to residue Arg-10 (a) in Orthorhombic RNase A and (ii) in 3RN3 [5]. Glu-2 forms 2 side-chain-side-chain H-bonds to Arg-10 in both structures. Ala-6 and Lys-7 each form a main-chain–main-chain H-bond to Arg-10. Asn-34 forms a main-chain-side-chain H-bond. Arg-33 forms a side-chain-main-chain H-bond and three main-chain-side-chain bonds. A total of nine inter residue H-bonds. Arg-10 which is a component residue towards the end of α-helix I (residues 3–13) interestingly does not form any H-bonds with solvent molecules. b In 3RN3 similar H-bonds form between Arg-33 and Asn-34 with Arg-10. Ala-6 does not interact with Arg-10 but both Glu-2 and Lys-7 do form H-bonds with Arg-10 which are not the same as those in Orthorhombic RNase A. In 3RN3 two water molecules form H-bonds with Arg-10 and one water molecule H-bonds to Orthorhombic RNase A Asn-34. Drawn with Biovia [19]