Measurement of unimolecular decay in peptides of masses greater than 1200 units by a reflecting time-of-flight mass spectrometer.
Daughter ions from decomposition of [M + H]+ parent ions have been observed in a time-of-flight mass spectrometer fitted with an ion mirror. Unit mass resolution is obtained for parent ions of masses up to several thousand u when the mirror voltage is set at a value determined by the usual velocity-focusing criterion for parent ions. Under this condition the daughter-ion resolution in the low-mass range suffers. Considerable improvement is obtained when the daughter-ion spectrum is examined in several segments, with the mirror voltage optimized for each segment. The daughter-ion spectrum from decay of metastable [M + H]+ parent ions in Substance P is measured using this technique. Reasons are suggested for differences between the spectrum obtained and a spectrum for the same compound recently obtained using a tandem double-focusing instrument.
Tang
X
X
Physics Department, University of Manitoba, Winnipeg, Canada.
Ens
W
W
Mayer
F
F
Standing
K G
KG
Westmore
J B
JB
D004723:Endorphins / Q000737:chemistry*; D004743:Enkephalin, Leucine / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D011498:Protein Precursors / Q000737:chemistry*; D013373:Substance P / Q000737:chemistry*
D004723:Endorphins; D011498:Protein Precursors; D013373:Substance P; D004743:Enkephalin, Leucine; C025681:alpha-neoendorphin