Different target surfaces for the analysis of peptides, peptide mixtures and peptide mass fingerprints by AP-MALDI ion trap-mass spectrometry.
The desorption/ionization behavior of individual peptides, an equimolare peptide mixture and a tryptic digest was investigated by AP-MALDI-IT-MS using four different target materials (gold-covered stainless steel (SS), titanium nitride-covered SS, hand-polished SS, and microdiamond-covered hardmetal) under identical conditions. Gold-covered as well as polished SS targets yielded comparable mass spectra for peptides and peptide mixture in the low pMol-range. The first target exhibited superior data down to the 10fMol-range. In contrast, titanium nitride-covered SS and microdiamond-covered hardmetal AP-MALDI-targets yielded poor sensitivity. These observations could be correlated with the surface roughness of the targets determined by 3D-confocal-white-light-microscopy. The roughest surfaces were found for titanium nitride-covered SS and microdiamond-covered hardmetal material showing both poor MS sensitivity. A less rough surface could be determined for the hand-polished SS target and the smoothest surface was found for the gold-covered target yielding the best sensitivity of all surfaces. These differences in the roughness having a strong impact on the ultimate sensitivity obtainable for peptide samples could be corroborated by electron microscopy. A peptide mixture covering a wide range of molecular weights and a tryptic protein digest (from 2-DE) exhibit the same behavior. This clearly indicates that the smooth gold-covered SS target is the surface of choice in AP-MALDI MS proteomics.
Pittenauer
Ernst
E
Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.
Kassler
Alexander
A
Haubner
Roland
R
Allmaier
Günter
G
D000808:Angiotensinogen / Q000737:chemistry; D001274:Atmospheric Pressure; D005345:Fibrinopeptide B / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D010449:Peptide Mapping; D010455:Peptides / Q000032:analysis*; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods
D010455:Peptides; D000808:Angiotensinogen; D005345:Fibrinopeptide B; D006046:Gold