Keywords: برچسب زدن ایزوتوپ پایدار; E. coli; Escherichia coli; NMR; nuclear magnetic resonance; PEP; phosphoenolpyruvate; scFv; single chain Fv; BPTI; bovine pancreatic trypsin inhibitor; LYZ; lysozyme C; MWCO; molecular weight cut-off; GSH; reduced glutathione; GSSG; oxidized glutathione;