Microchannel plate for surface-induced dissociation in mass spectrometry.

A new method for surface-induced dissociation of molecular ions, applied to tandem mass spectrometry, is achieved by collisions at a grazing angle on the inside channel surfaces of a microchannel plate. This technique, termed microchannel SID, is demonstrated by using both positive and negative parent ions in the energy range of 500-2000 eV. Fragmentation spectra of the pentapeptide leucine-enkephalin (555 daltons) at 500 eV show good sequence information with a net fragmentation efficiency of 14%.

Revision of the blocked N terminus of rat heart fatty acid-binding protein by liquid secondary ion mass spectrometry.

The primary structure of rat heart muscle fatty acid-binding protein was investigated by liquid secondary ion mass spectrometry. The protein was digested with trypsin, chymotrypsin, and Staphylococcus aureus V8 protease and the resulting peptides were separated by reverse phase high performance liquid chromatography. The masses of the protonated molecular ions (MH+) of the tryptic, chymotryptic, and S.

Evidence for isoaspartyl (deamidated) forms of mouse epidermal growth factor.

A variant form of mouse submaxillary gland epidermal growth factor (EGF) was identified by isocratic reversed-phase HPLC of EGF obtained by Bio-Gel P-10 column chromatography ("culture grade"). The variant form was essentially absent in preparations of EGF further purified by chromatography on DEAE-cellulose ("receptor-grade" EGF). The spectral properties and amino acid composition of the variant form (EGF-I) could not be distinguished from those of the intact polypeptide isolated by HPLC (alpha-EGF).