Fig. 4

Functional analysis of key residues in loops 3, 4, and 6. a Measurements of the catalytic activity relative to WT TfCel5A and substrate binding affinity of loop 3 and 4 mutants. b Measurements of the catalytic activity relative to WT TfCel5A and substrate binding affinity of loop 5, 6, and 7 mutants. c Hydrogen bonding interaction between the active site residues and the O3ʹ-hydroxyl group of the sugar at the − 1 subsite. d Hydrogen bonding interaction between the active site residues and the O2ʹ-hydroxyl group of the sugar at the − 1 subsite