Application of matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in determining arginine esterase from snake venom

Using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The homogeneities and molecular weights of three arginine esterases from snake venom, which possessing therapeutic use in myocardial infarction, were determined and compared, MALDI-TOF-MS is possessed of high accuracy, high sensitivity and rapidity. MALDI-TOF-MS and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) can provide complementary and confirmatory results information. MALDI-TOF-MS can be directly used as an important method for the purification of snake venom complexes successfully.

NMR relaxation studies of GdDTPA in human serum albumin solution

The water relaxation enhancement behavior of GdDTPA in human serum albumin (HSA) solution has been studied. The results indicate that GdDTPA can integrate noncovalently with HSA, mainly in forms of (GdDTPA)HSA and (GdDTPA),HSA, for which the apparent equilibrium constants are 0.05 mM(-1) and 0.02 mM(-2), respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.

The NMR-spectroscopic and X-ray crystal-structural characterization of two Cp*Ir halfsandwich complexes containing the 1,2-dicarba-closo-dodecaborane-1,2-diselenolato ligand

The reaction of [Cp*IrCl2](2) with dilithium 1,2-orthocarborane-1,2-diselenolate 3 leads to the green 16-electron diselenolene complex [Cp*Ir{Se2C2(B10H10)}] (4) which takes up two-electron ligands such as trimethylphosphane to give the 18-electron diselenolate derivative [Cp*Ir(PMe3)-{Se2C2(B10H10)}] (5). The molecular structures of 4 and 5 were determined by X-ray crystal structure analysis. The Se-77-nuclear shielding in 4 is lower by almost 500 ppm relative to that in 5.

The application of matrix-assisted laser desorption jonization mass spectrometry in enzymes of Agkistrodon blomhoffii Ussurensis venom analysis

The matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) spectra of four enzymes (PLA, AEase, Fibrolase, L-a.a. oxidase) in Agkistrodon blomhoffii Ussurensis venom, were given and interpreted. The experiment data showed that MALDI-TOF-MS can be used directly in enzyme analysis with high sensitivity and rapidity. In addition, the results were better than those from sodium dodecyl sulfate-polyacrylamide.

Studies on electrospray mass spectrometry of some narcotic drugs

Using electrospray ionization (ESI) and tandem mass spectrometry techniques, the protonic positions in protonated molecular ions of some narcotic drugs were studied, The data of ESI/MSn experiments of morphine and deuterium-loaded morphine were first discussed. The protonic position was considered to locate on oxygen atom of cyclic ether in morphine molecular, Compared with the same and different: ions among morphine, codeine, acetylcodeine and dihydrocodeine, the protonic positions in protonated molecular ions of these compounds were further determined. The fragmentation mechanism of morphine in ESI/MSn: experiments was also repored in the paper, and there were similar dehydrolysis mechanism in gas phase or in liquid phase for morphine.

Quantitative analysis of pethidine using liquid secondary ion and tandem mass spectrometry

A method for the quantatitive determination of pethidine in human urine by liquid secondary ion and tandem mass spectrometry is presented. Quantification was carried out by using ketamine as internal standard. It was found that the collision-induced dissociation (CID) spectrum of the [M + H](+) ion of pethidine exhibited a prominent daughter ion at mit 220 and ketamine also yielded the same daughter ion at nit 220, For ((quadrupole)) quantitative analysis, the first quadrupole mass filter was set to transmit mit 220 and a narrow-range magnet scan yielded a spectrum of parents, including mit 238 and 248, corresponding to ketamine and pethidine, respectively. Copyright (C) 1999 John Wiley & Sons, Ltd.

Mass spectrometry study combined with theoretical calculation on the unimolecular fragmentation of tetrahydroimidazole-substituted methylene beta-diketones

Studies of low-energy collision-induced dissociation and isotopic labeling on ionized tetrahydroimidazole-substituted methylene P-diketones by tandem mass spectrometry showed that their unimolecular fragmentations may involve the reactions of intermediate ion/neutral complexes and multistep rearrangements. The corresponding mechanisms were proved by semiemipirical calculations of PM3 and AM1 methods.

配合物Ru(dcbpy)(phen)_2(PF_6)_2的2D-NMR分析

用一维ＮＭＲ方法研究了新型电化学发光探针Ru(dcbpy)(phen)2(PF6)2的立体结构，借助二维1H-1HCOSY和1H-13ccosy实验技术对其氢谱和碳谱进行了完全的归属，并给出了其氢谱和碳谱的化学位移值。

Gd(DTPA-BIN)的热力学性质及与牛血清白蛋白作用的NMR研究

报道了一种新合成的DTPA酰胺类衍生物DTPA－BIN的质子解离过程，其质子化常数总和与稳定性大于DTPA－BMA并采用核磁共振弛豫分析法研究了Gd（DTPA、BIN）在水溶液和牛血清白蛋白溶液中的诱导弛豫增强性质．Gd（DTPA－BIN）配合物在水溶液中弛豫效率为3.28mmol－1·L-1。牛血清白蛋白分子可以与Gd（DTP－BIN）配合物非共价地结合，这种非共价结合体的旋转相关时间明显长于自由配合物，使Gd（DTPA－BIN）在蛋白质溶液中弛豫效率增高．本文结果表明弛豫增强方法可以用来研究顺磁性金属配合物与蛋白质之间的相互作用情况.

联萘衍生物的NMR表征Ⅱ.2,2′-(3,4-四酸二酐)二苯甲酰氧基-1,1′联萘

用一维 1HNMR、13CNMR方法研究了2,2′-(3,4 -四酸二酐)二苯甲酰氧基 -1,1′联萘的结构 ,并通过二维1H - 1H同核相关、13C - 1H异核相关及13C - 1H异核远程相关谱进一步地确定其1H谱和13C谱中各谱峰的归属 ,为同类化合物的表征提供了依据。

利用~1H-NMR计算环化氯丁橡胶的环化度和溶剂参与量

对环化氯丁橡胶的1H -NMR谱进行了归属 ,并推导出计算环化氯丁橡胶 (CR)的环化度和溶剂参与量的公式。

Intensity exaggeration of endohedral metallofullerenes in laser-desorption-ionization time-of-flight mass spectrometry

The laser-desorption-ionization time-of-flight mass spectrometry and desorption-electron-ionization mass spectrometry were employed for the characterization of metallofullerenes extract. it was found that the relative intensities of metallofullerenes in this positive-ion, negative-ion LD-TOF MS and DEI MS were much different. This phenomenon should have relationship with the peculiar ionization energies and electron affinities of metallofullerenes.

Detection of specific noncovalent protein-fullerenols complexes by matrix-assisted laser desorption ionization mass spectrometry

Matrix-assisted laser desorption ionization (MALDI) mass spectrometry is difficult for the characterization of noncovalent complexes hitherto because of the limitations in acidic matrix, sample preparation, laser-induced polymerization and adduct formation with matrix. Under our experimental conditions, sinapinic acid is used as a matrix, the specific noncovalent interactions of protein with fullerenols were observed by MALDI mass spectrometry. Some mass spectrometric features, such as mass shifts, broad adduct peaks and stoichiometries, showed that the specific non-covalent complexes between protein and fullerenols have been formed at a ratio of 1 : 4 for hemoglobin-fullerenols or 1 : 1 for myoglobin-fullerenols. The results implied that fullereneols could be used to protect partly hemoglobin from decomposition in acidic media, and therefore, it is possible to realize the molecular weight determination of a quaternary protein by MALDI mass spectrometry via the addition of specific organic compound in the matrix.

NMR studies of Gd(DTPA-BIN) in human serum albumin solution

Stable gadolinium complexes, such as Gd(DTPA) and Gd(DOTA), are usually used as the contrast agents for magnetic resonance imaging(MRI). Reported here are the enhanced relaxation properties of a novel gadolinium complex, diethylene-triaminopentaacetate Lis (isoniazid) [Gd(DTPA-BIN)], in aqueous and in human serum albumin(HSA) solution, which indicates that (1) two Gd(DTPA-BIN) can integrate non-covalently with one HSA with an equilibrium constant of 0. 02 mmol(-2) . L-2 ; (2) the relaxivities are 3. 28 and 4. 92 mmol(-1) . L . s(-1) for the free Gd(DTPA-BIN) and the [Gd(DTPA-BIN)](2), HSA conjugator, respectively; (3) the rotational correlation time of protein conjugator is notably higher than that of the free complex, The above results may imply that Gd(DTPA-BIN) has a higher tissue selectivity than that of its parent Gd(DTPA).

Electrospray ionization mass spectrometry of cyclodextrin complexes with amino acids in incubated solutions and in eluates of gel permeation chromatography

1:1 complexes of beta-cyclodextrin (CD) with three amino acids (Gly, Phe and Trp) have been detected as ions in the gas phase using infusion positive and negative ion electrospray ionization mass spectrometry (ESI-MS). In contrast with the positive ion ESI mass spectra of simple aqueous solutions, the aggregates and adducts usually formed in the ESI process did not appear in the positive ion ESI spectra of solutions buffered with ammonium acetate (NH4Ac), even at higher analyte concentrations, These studies suggest that addition of buffer and/or use of a low analyte concentration should be used to overcome formation of aggregates and metal ion adducts in such mass spectrometry studies. Also, the deprotonated complexes are dissociated by collision induced dissociation (CID) to form an abundant product ion, the deprotonated CD, requiring transfer of a proton to the amino acid carboxyl group, To understand formation of complexes in the gas phase, gel permeation chromatography (GPC) was used to separate free amino acids (AAs) from complexes in an incubated solution. The ESI mass spectra of the GPC fractions show the presence of 1:1 complexes of both CD-aromatic amino acids and CD-aliphatic amino acids. Compared with CD-aliphatic amino acid complexes, CD-aromatic amino acid complexes appear to be destabilized in the gas phase, possibly because the hydrophobic interaction which binds the aromatic group of amino acids in the CD cavity in solution may become repulsive when solvent evaporates from the droplets during the electrospray process, whereas those complex ions formed as proton bound dimers are stabilized by electrostatic forces, the major binding force for such complexes in the gas phase. In addition, the GPC technique coupled with off-line ESI-MS can rapidly separate CD complexes by size, and provides some information on the character of the complexes in solution. (C) 1998 John Wiley & Sons, Ltd.