Structural characterization of actinomycin D using multiple ion isolation and electron induced dissociation

Area of Science:

• Analytical Chemistry
• Natural Product Chemistry
• Biochemistry

Background:

• Non-ribosomal peptides exhibit significant structural diversity due to their enzymatic biosynthesis.
• Standard peptide sequencing methods are often insufficient for these complex molecules.
• Actinomycin D is a representative non-ribosomal peptide with a complex structure.

Purpose of the Study:

• To investigate the structural elucidation of non-ribosomal peptides using advanced mass spectrometry techniques.
• To compare the efficacy of collision activated dissociation (CAD) and electron induced dissociation (EID) for actinomycin D.
• To develop an accurate internal calibration method for fragment ions.

Main Methods:

• Utilized Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometry.
• Employed tandem mass spectrometry techniques: collision activated dissociation (CAD) and electron induced dissociation (EID).
• Combined EID with multiple ion isolation for enhanced fragmentation and calibration.

Main Results:

• Electron induced dissociation (EID) provided more comprehensive structural data for actinomycin D compared to CAD.
• Fragmentation of sodium and lithium adducts with EID yielded additional structural insights.
• Multiple ion isolation with EID improved product ion intensity and enabled accurate internal calibration (<0.3 ppm uncertainty).

Conclusions:

• The combination of multiple ion isolation and EID in FTICR mass spectrometry is a powerful approach for detailed structural analysis of non-ribosomal peptides.
• This method offers high accuracy for fragment ion calibration.
• It significantly enhances the structural information obtainable from complex natural products like actinomycin D.