Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to reveal the substrate specificity of the peptidyl-cysteine decarboxylase EpiD.
The microbial flavoenzyme EpiD catalyzes the oxidative decarboxylation of peptidyl-cysteines to peptidyl-aminoenethiols. These unusual C-terminally modified peptides are intermediates in the biosynthesis of the tetracyclic peptide antibiotic epidermin, which belongs to the lantibiotics family. The peptide SFNSYCC represents the C-terminal partial sequence of the natural precursor peptide EpiA. EpiA is posttranslationally modified to form finally the lantibiotic epidermin. The substrate specificity of EpiD was investigated using high-resolution mass spectrometry and the heptapeptide library SFNSXCC. The enzymatic conversion of particular peptides can be observed by a mass loss of m/z 46. In contrast to the previously used triple quadrupole instrument, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was able to resolve and detect all precursor and converted peptides with identical nominal masses in a single measurement, avoiding the necessity to investigate single peptides. Furthermore, a new substrate SFNSCCC of the enzyme EpiD was detected within the reaction mixture.
Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
Dietmar G
DG
Schmid
Florian
F
Majer
Thomas
T
Kupke
Günther
G
Jung
D002262:Carboxy-Lyases; D017357:Cyclotrons; D005583:Fourier Analysis; D010088:Oxidoreductases / Q000032:analysis / Q000378:metabolism*; D019151:Peptide Library; D021241:Spectrometry, Mass, Electrospray Ionization; D013212:Staphylococcus epidermidis / Q000201:enzymology*; D013379:Substrate Specificity
D019151:Peptide Library; D010088:Oxidoreductases; C075971:epidermin decarboxylase; D002262:Carboxy-Lyases