Fig. 4

Structure analysis of the mutant κ-carrageenase S190R. (a) The three-dimensional structure of S190R. The catalytic triad was represented by yellow sticks and the mutation site was represented by a green stick. (b) Overlapping schematic diagram of the overall 3D models for S190R and Cgk-K142. The yellow model represented the S190R, the blue model represented Cgk-K142, and the catalytic triads of S190R and Cgk-K142 were represented by the yellow and blue sticks, respectively. (c) Overlapping schematic diagram of the important residues for S190R and Cgk-K142. The important residues of S190R and Cgk-K142 were represented by the yellow and blue sticks, respectively. (d) The model of the mutant κ-carrageenase S190R. The “finger” regions around the catalytic channel were numbered from F1 to F6. The catalytic triad E162-D164-E167 was marked in the form of yellow sticks