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A 'top-down' protein separation and identification methodology makes use of ion parking approach to facilitate the gas-phase concentration and purification of precursor ions from a complex protein mixture. Dissociation of the ions using a quadrupole ion trap and matching up with the ion spectra database identify the proteins in the mixture.

An examination of the gas-phase ion-molecule reactions of neutral alanylglycine with the acylium ions RCO+ (R=CH3, CD3, C6H5, C6F5 and (CH3)2N) is presented.

The implementation and results from a novel strategy for peptide sequence and modification analysis (femtosecond laser-induced ionization/dissociation (fs-LID)) involving the use of ultrashort laser pulses for energy deposition and nonergodic dissociation in a quadrupole ion trap mass spectrometer are presented. The studies have shown that fs-LID is a viable alternate ion activation strategy for peptide sequence and modification analysis.

A study demonstrates that dihydroneopterin aldolase (DHNA) catalyzes the conversion of 7,8-dihydroneopterin to 6-hydroxymethyl-7,8-dihydropterin in the folate biosynthetic pathway. The conserved tyrosine residue plays only a minor role in the formation of the enol reaction intermediate but a critical role in the protonation of the enol intermediate to form 6-hydroxymethyl-7,8-dihydropterin.