J. Mass Spectrom. Soc. Jpn., 48(3), 179-186, 2000
We evaluated applicability of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to protein identification across species. Nano-electrospray FT-ICR MS enabled acquisition of accurate mass spectra of protein digests at a picomole level sensitivity. Peptide mass maps with a ppm level accuracy were routinely obtained by spraying whole protein digests without internal mass calibrant. The accurate peptide mass maps allowed narrowing of database search-windows for peptide-mass fingerprinting and the search noise was substantially reduced. This method of protein identification was applied to a rat liver protein, which had not been sequenced previously but had been biochemically characterized as an aldehyde oxidase. The rat liver protein was successfully correlated to human and bovine counterparts across the species boundaries by peptide-mass fingerprinting with an accurate tryptic mass map. Identity of the rat protein was further confirmed by accurate fragment-ion masses obtained by hexapole-storage-assisted capillary-skimmer dissociation of a peptide mixture.
J. Mass Spectrom. Soc. Jpn., 48(2), 187-210, 2000
Proteomics is an effective approach for understanding of biology with the global change in protein expression as visualized by two-dimensional gel electrophoresis and characterized by mass spectrometry. For proteomics to be widely adopted, a robust technology must be established that allows the large-scale discovery research needed for an exhaustive approach to protein science. And a drastic increase in the rapidity and sensitivity of protein identification is needed for proteome analysis. In this paper, I summarize methodology of rapid and micro amino acid sequencing and recent trends toward automation in instrumentation and software for protein identification by mass spectrometry.
J. Mass Spectrom. Soc. Jpn., 48(2), 211-220, 2000
ESI/MS of the noncovalently and covalently bound complexes of drugs with protein is useful to study on pharmacological effect or toxicological symptom of drugs because of solving the problem with far greater easier by MS than any other method. ESI/MS shows that protein folding of FKBP generates a native three-dimensional structure with multiple charged ions (+6
+8) at pH 6.8 from a denature linear one-dimensional structure with multiple charged ions (+10+20) at pH 3.0. The noncovalently bound complex of FKBP-FK506 (12.6 kd) is observed a little in mixed solution of FK506 (0.8 kd) and FKBP (11.8 kd) at pH 3 or pH 6.8 by ESI/MS and its deconvoluted MS. But much amount of FKBP-FK506 (12.6 kd) generate during folding of FKBP after the pH of the solution containing FKBP and FK506 changes from pH 3.0 to pH 6.8. Drug A is a large ring compound with aminal bond and produced the covalent complex with human serum albumin (DA=HSA) that was measured easily by LC/ESI/MS and its deconvoluted mass. The stoichiometry of ratio (Drug : HSA) was shown by molecular ions at m/z 67,610 (1 : 1 DA=HSA complex), 68,792 (2 : 1 DA=HSA complex), 70,187 (3 : 1 DA=HSA complex). The main metabolites acyl glucronides of Drug B and C produced the covalent binding complex with HSA (DB=HSA and DC=HSA) that were easily measured by post-averaging scan of LC/ESI/MS and its deconvoluted MS. These data are useful to improve the post candidate and decide stop and continue of development.
J. Mass Spectrom. Soc. Jpn., 48(2), 221-227, 2000
We developed an assay method that utilizes ESI and ion trap mass spectrometry to rapidly determine the binding nature of drugs with oligodeoxynucleotides and to assess their relative affinities, stoichiometries and specificities in non-covalent interactions. Selectivity experiments show that the drugs H2TMpyP and CuTMpyP bind via mixed modes, whereasFeTMpyP and MnTMpyP interact by groove binding only. Competitive binding experiments show that the order for the drugs with duplex 5'ATATAT3' was H2TMpyP-CuTMpyP
FeTMpyP-MnTMpyP. We also investigated the gas-phase stability of duplex oligodeoxynucleotides and the non-covalent complexes by monitoring the dissociation profiles of those non-covalent associations as a function of collision energy in the ion-trap mass spectrometer. We defined a half-wave collision energy which corresponds to the collision energy (in percentage of the maximum tickling voltage) at which the relative abundance of the complex ion had dropped to 50% and used this as an estimate of the gas-phase stability. The gas-phase stability of double-stranded oligonucleotide correlates with the number of H-bonds within the duplex. The noncovalent complexes of the drugs (Distamycin A, Actinomycin D, and Mn(III)TMpyP) and the duplex oligonucleotides are more stable in the gas phase than the duplexes themselves.
J. Mass Spectrom. Soc. Jpn., 48(2), 231-237, 2000
FAB mass spectrometry coupled with the host-guest complexation method was used to distinguish some amino sugars (1-8) including glucosamine, galactosamine, and mannosamine, etc. The method characteristically used a 1 : 1 mixture of the chiral crown ether host whose enantiomer was isotopically labeled. Diastereomer differentiation of a given amino sugar salt (G+) was simply measured with a given host pair (A or B) (HRRRR : HSSSS-d6=1 : 1) from the peak intensity ratio of the two diastereomeric host-guest complex ions as I [(HRRRR+G)+] / I [(HSSSS-d6+G)+]
IRIS (abbreviation). The stereoisomer differentiation was performed by the IRIS values in the range from 0.4 to 2.0 (for the use of the host pair A) and from 0.4 to 3.4 (for the use of the host pair B). The five underivatized amino sugar hydrochloride salts (1-5) were successfully differentiated using the present chiral recognition FAB mass spectrometry. The stereoisomer-(13C)-labeled guest method was also presensed to evaluate their relative complexation abilities.
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