Distinguishing N- and C-terminus ions for mass spectrometry sequencing of proteins without prior degradation.
Identifying complementary pairs of fragment ions, b-type vs y-type, is a key step in mass spectral sequencing of proteins without degradation prior to ionization. Observations that b-type ions tend to be less stable than y-type have been extended to carbonic anhydrase (29 kDa) as a model protein. Infrared multiphoton dissociation (IRMPD) of 24+, 27+, 30+ molecular ions shows y-type ions from complementary pairs require, on average, 27% longer irradiation times for onset of abundance decrease, while in nozzle/skimmer dissociation of all charge states, y-type ions require a 20% higher potential difference. In some cases, b-ion dissociation appears to accompany its formation, as its rate of increase with increasing energy deposition is far less than that of its y-complement.
Aaserud
D J
DJ
Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
Little
D P
DP
O'Connor
P B
PB
McLafferty
F W
FW
D000107:Acetylation; D000596:Amino Acids / Q000032:analysis*; D002256:Carbonic Anhydrases / Q000737:chemistry* / Q000528:radiation effects; D008401:Gas Chromatography-Mass Spectrometry; D011506:Proteins / Q000737:chemistry* / Q000528:radiation effects; D017421:Sequence Analysis / Q000379:methods*
D000596:Amino Acids; D011506:Proteins; D002256:Carbonic Anhydrases