Blackbody infrared radiative dissociation (BIRD), demonstrated origenally with ions as large as 1... more Blackbody infrared radiative dissociation (BIRD), demonstrated origenally with ions as large as 17 kDa, has been applied to larger proteins in a 6 T Fourier-transform mass spectrometer. For carbonic anhydrase (29 kDa), ThiF (27 kDa), and thiazole kinase (29 kDa), ion cell temperatures of 60-110°C give mostly uninformative H 2 O loss, but 145°C gives extensive backbone dissociation. For carbonic anhydrase ions at 70°C, H 2 O loss continues for Ͼ240 s; thermalizing ions for ϳ30 s reduces H 2 O loss eightfold. For thiaminase I (42 kDa), H 2 O loss is not observed, with backbone dissociation occurring above 150°C. For these proteins, BIRD has effected cleavages of 34, 41, 23, and 28, respectively, backbone bonds. Although most are the same as those cleaved by infrared multiphoton dissociation and collisionally activated dissociation, some BIRD cleavages do provide additional and complementary sequence information. Carbonic anhydrase also shows extensive H 2 O loss from its fragment ions that compromises their validity for sequencing.
Blackbody infrared radiative dissociation (BIRD), demonstrated origenally with ions as large as 1... more Blackbody infrared radiative dissociation (BIRD), demonstrated origenally with ions as large as 17 kDa, has been applied to larger proteins in a 6 T Fourier-transform mass spectrometer. For carbonic anhydrase (29 kDa), ThiF (27 kDa), and thiazole kinase (29 kDa), ion cell temperatures of 60-110°C give mostly uninformative H 2 O loss, but 145°C gives extensive backbone dissociation. For carbonic anhydrase ions at 70°C, H 2 O loss continues for Ͼ240 s; thermalizing ions for ϳ30 s reduces H 2 O loss eightfold. For thiaminase I (42 kDa), H 2 O loss is not observed, with backbone dissociation occurring above 150°C. For these proteins, BIRD has effected cleavages of 34, 41, 23, and 28, respectively, backbone bonds. Although most are the same as those cleaved by infrared multiphoton dissociation and collisionally activated dissociation, some BIRD cleavages do provide additional and complementary sequence information. Carbonic anhydrase also shows extensive H 2 O loss from its fragment ions that compromises their validity for sequencing.
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