Function of four tryptophan residues on <scp>Cel7A</scp> catalytic efficiency: Insight into cellulase screening strategy based on natural cellulose or cellulose analogs

There is a high level of conservation tryptophans within the active site architecture cellulase family, whereas function four in catalytic domain Cel7A unclear. By mutating tryptophan residues from Penicillium piceum (PpCel7A), binding affinity between PpCel7A and p-nitrophenol-D-cellobioside (pNPC) was reduced as determined by Michaelis–Menten constants, molecular dynamics simulations, fluorescence spectroscopy. Furthermore, variants showed cellobiohydrolase activity against cellulose analogs or natural cellulose. Therefore, it could be concluded played critical role substrate binding. Mutagenesis results indicated that W390 stacking interactions at -2 an essential facilitating distortion to -1 site. As soon altered, mutation would inevitably affect substrate. Interestingly, no clear relationship found pNPC Avicel. pNP contains many electrophilic groups may result overestimation constant comparison Consequently, screening improved using divert attention target direction for lignocellulose biorefinery. Clarifying mechanism diversity on give better insight into selecting strategy.