Matrix-assisted laser desorption/ionization, fast atom bombardment and plasma desorption mass spectrometry of polyethylene glycol esters of (2-benzothiazolon-3-yl)acetic acid.
ABSTRACT Fast atom bombardment (FAB), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and plasma desorption (PD) mass spectra of newly synthesized polyethylene glycols (PEGs), (M(w) 600-4000 Da) chemically modified with biologically active (2-benzothiazolon-3-yl)acetyl end-groups are described (products 1-6). The spectra were also used for the determination of the molecular mass characteristics (number average (M(n)) and weight average (M(w)) molecular masses) of the initial and modified PEGs. As expected, M(n) and M(w) of the modified samples are higher than those of the non-modified samples. However, it is shown that molecular mass dispersity (determined by the comparison of the polydispersity indices (PDI = M(w)/M(n)) of both types of PEGs) essentially do not change during this modification. The FAB mass spectra, together with molecular species, show the presence of abundant [M + Na](+) ions of product 1 and [M + Na + H](+) species of 2 and 3, and [M + Na + 2H](+) of product 4. Two main series of fragment ions, derived from the cleavage of the ether bonds, are observed. The number fractions of the molecular adduct ions and fragment adduct ions, determined from the FAB and PD mass spectra of the modified PEGs, are compared. The MALDI-TOF mass spectra of compounds 1-6 show the presence of two series of polymers. The most abundant peaks are due to [M + Na](+) and [M + K](+) ions originating from the polymers, in which the two terminal hydroxyl groups of PEGs are esterified with (2-benzothiazolon-3-yl)acetic acid. The less abundant peaks are due to the monosubstituted polymers.
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ABSTRACT: High molecular weight gangliosides (GD1a, GD1b, GT1a, and GT1b) and neutral glycosphingolipids (Forssman antigen, globoside, and CTH) containing various fatty acids were analyzed by positive and negative ion fast atom bombardment mass spectrometry (POS-FAB-MS and NEG-FAB-MS) without any derivatization. NEG-FAB-MS of the molecules gave intense peaks of the molecular ion species, (M-H)-, and many fragment ions useful for the elucidation of carbohydrate structure were also detected with significant intensity. The fragment ions were assessed to be cleaved at the glycosidic linkages sequentially from the non-reducing end with or without the ceramide portion and it was possible to distinguish structural isomers having different binding positions of sialic acid. All molecular ion species of neutral glycosphingolipids with various fatty acids were detected at intensities that were in accordance with the relative abundance of the fatty acids.Journal of Biochemistry 05/1984; 95(4):971-81. · 2.72 Impact Factor
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ABSTRACT: Conformational data for macromolecules in the gas phase have been obtained by the coupling of a matrix-assisted laser desorption ion source to an ion chromatograph. A series of polyethylene glycol (PEG) polymers "cationized" (converted to a cation) by sodium ions (Na(+)PEG9 to Na(+)PEG19) and a protonated neurotransmitter protein, bradykinin, were studied. Mobilities of Na(+)PEG9 to Na(+)PEG19 are reported. Detailed modeling of Na(+)PEG9 with molecular mechanics methods indicates that the lowest energy structure has the Na(+) ion "solvated" by the polymer chain with seven oxygen atoms as nearest neighbors. The agreement between the model and experiment is within 1 percent for Na(+)PEG9, Na(+)PEG13, and Na(+)PEG17, giving strong support to both the method and the deduced structures. Similar agreement was obtained in initial studies that modeled experimental data for arginine-protonated bradykinin.Science 04/1995; 267(5203):1483-5. · 31.03 Impact Factor
Article: A new transferrin in New Guinea.[show abstract] [hide abstract]
ABSTRACT: IN 1957 Smithies1, using the technique of starch-gel electrophoresis, described inherited variants of human beta-globulins. Smithies and Hiller2 established the identity of these beta-globulins with the iron-binding protein, trans-ferrin, and this was afterwards confirmed with iron-59 and autoradiography3. During the past few years widespread sampling of human populations has demonstrated the existence so far of 14 transferrins. In order of decreasing mobility in starch-gel electrophoresis these are4: B0, BO-1 B1, B1-2, B2, B3, C, D0, D4 (D0-1), Dmontreal Dchi, D1, D2, D3. The present communication reports another transferrin of the B series.Nature 06/1963; 198:589. · 38.60 Impact Factor