Identification of the catalytic nucleophile of the Family 31 alpha-glucosidase from Aspergillus niger via trapping of a 5-fluoroglycosyl-enzyme intermediate
Ss. Lee et al., Identification of the catalytic nucleophile of the Family 31 alpha-glucosidase from Aspergillus niger via trapping of a 5-fluoroglycosyl-enzyme intermediate, BIOCHEM J, 359, 2001, pp. 381-386
The mechanism-based reagent 5-fluoro-alpha -D-glucopyranosyl fluoride (5F a
lpha G1cF) was used to trap a glycosyl-enzyme intermediate and identify the
catalytic nucleophile at the active site of Aspergillus niger alpha -gluco
sidase (Family 31). Incubation of the enzyme with 5FaG1cF, followed by pept
ic proteolysis and comparative liquid chromatography/MS mapping allowed the
isolation of a labelled peptide. Fragmentation analysis of this peptide by
tandem MS yielded the sequence WYDMSE, with the label located on the aspar
tic acid residue (D). Comparison with the known protein sequence identified
the labelled amino acid as Asp-224 of the P2 subunit.