2.3 Computaional prediction for Sucrose isomerase
thermostability
As starting point, the structure of WT and other mutants were modeled
using the SI from Erwinia rhapontici NX5 (PDB: 4hph.1.A) as
template with 74.10% sequence identity by SWISS-MODEL
(https://www.swissmodel.expasy.org).[27]MolProbity[28] and
PROCHECK[29] were applied for model evaluation,
and evaluation results of WT are presented as Ramachandran plot (Fig
S1). To identify the hot-spots for site-directed mutagenesis based on
the ΔΔG change, FoldX 3.0 algorithm was utilized to estimate the folding
free energy of SI. A standardized script written in python was performed
to change all positions of the protein sequence to other 19 amino acids.
The relative folding free energy changes
(ΔΔG = ΔGMut − ΔGWT) was calculated
after each residue was mutated into the other amino acids.