N, C and Sn NMR and other spectroscopic studies of 8-quinolinol, its O- and N-methyl derivatives, and chelate di- and tri-organotin(IV) complexes

The nature of the 8-quinolinato ligand in various forms has been examined by ¹⁵N, ¹³C and ¹¹⁹Sn NMR spectroscopy, with evidence also from electronic spectroscopy. These forms include 8-quinolinol (HQ), 8-quinolinate, the 8-hydroxyquinolinium ion, O- and N-methyl derivatives, 8-methoxyquinoline (MeQ), the zwitterionic N-methylquinolinium-8-olate and the N-methylquinolinium ion, and the chelating ligand in organotin(IV) complexes. The ¹⁵N shift from MeQ to HQ affords a measure of the intramolecular hydrogen bonding in HQ. The ¹⁵N shifts and ²J(¹⁵N¹H) couplings afford criteria of chelation, and the O- and N-methyl compounds provide useful reference points for its assessment. Evidence for chelation is demonstrated in three groups of compounds, [SnR₂Q₂] (R = Me, Et, Buⁿ, Octⁿ or Ph), [SnR₃Q] (R = Me, Et, Buⁿ or Ph) and [SnR₂ClQ] (R = Me, Et, Buⁿ or Octⁿ), the ¹⁵N and ¹¹⁹Sn shielding increasing from the [SnR₃Q] to the [SnR₂Q₂] compounds.     

Preparation and enantiomer separation behavior of selectively methylated β-cyclodextrin-bonded stationary phases for high performance chromatography

Native and three selectively methylated β-cyclodextrin (β-CD)-bonded stationary phases without an unreacted spacer arm for liquid chromatography were prepared, where heptakis(2-O-methyl)-β-CD, heptakis(3-O-methyl)-β-CD and heptakis(2,3-di-O-methyl)-β-CD were used as the methylated β-CDs. The enantiomer separation abilities of the resulting β-CD stationary phases for 12 pairs of dansylamino acid enantiomers and six pairs of N-3,5-dinitrobenzoyl amino acid methyl esters as model solutes were investigated. The effects of pH and methanol content of the mobile phase on the retention and resolution were examined to optimize the mobile phase conditions. The optimum resolution for the dansylamino acids was achieved using a mobile phase consisting of 1.0% triethylammonium acetate buffer (pH 5.0)–methanol (v/v 4/6) on the β-CD stationary phase. Heptakis(3-O-methyl)- and heptakis(2,3-di-O-methyl)-β-CD-bonded stationary phases showed little enantiomer separation abilities for the dansylamino acids. The heptakis(2-O-methyl)-β-CD-bonded stationary phase exhibited no enantioselectivities for those solutes.

For the N-3,5-dinitrobenzoyl amino acid methyl esters, the optimum resolution was achieved using a mobile phase consisting of 1.0% triethylammonium acetate buffer (pH 5.0)–methanol (v/v 9/1) on a heptakis(2-O-methyl)-β-CD stationary phase. The heptakis(2,3-di-O-methyl)-β-CD-bonded stationary phases exhibited no enantioselectivities for the N-3,5-dinitrobenzoyl amino acid methyl esters. β-CD and heptakis(3-O-methyl)-β-CD-bonded stationary phases had no enantiomer separation abilities for those solutes except for the N-3,5-dinitrobenzoyl phenylalanine methyl ester.     

Influence of DFT-calculated electron correlation on energies and geometries of retinals and of retinal derivatives related to the bacteriorhodopsin and rhodopsin chromophores

DFT-calculations were performed on retinal in the all-trans, 1, 11-cis-12-s-cis, 2, and 11-cis-12-s-trans configuration, 3, and on the corresponding N-methyl Schiff base and protonated N-methyl Schiff base derivatives; for the latter, the corresponding 6-s-trans conformations and the 6-s-trans-13-cis-14-s-trans isomer which play a role in the bacteriorhodopsin photocycle were also studied. All geometries were fully optimized using the Becke- three-parameter Lee-Yang-Parr method in conjunction with the 6-31G^** basis set (B3LYP/6-31G^**). The stabilities in order of increasing energy are 1, 3 and 2 regardless of the type of substitution of the end group. While the energy of 3 relative to 1 is almost constant (5 ± 0.2 kcal mol⁻¹), the relative energy of 2 depends somewhat on the nature of the functional group: it is highest in the protonated Schiff base derivative 2-SBH + with its steric congestion along the C12-C13 bond. Comparison with results previously obtained on the basis of RHF/6-31G^** ab initio calculations reveals that the B3LYP method is more biased towards π-electron delocalization. This is indicated by the reduced degree of double bond fixation along the chromophore and also in the increased tendency towards planarization as manifest, e.g. by the change of the C5-C6-C7-C8 dihedral angle between the cyclohexene ring and the open chain double bond system.     

Electronic structure and conformational properties of (carboxy-alkenyl)-phosphonic acids

The general conformational properties and electronic structure of (carboxy-alkenyl)-phosphonic derivatives were determined at RHF/STO-3G^* level. In all the series, low rotation barriers were found for the two C=C/P=O conformers. In the compounds in which the interactions between the carboxylic and phosphonic moieties are smaller, the most stable conformers are the C=C/P=O s-cis ones. In most of the conformers, the C=C/C=O system presents the disposition s-cis. The Z-(2-carboxy-vinyl) and Z-(2-carboxy-propenyl) phosphonic acids present intramolecular hydrogen bonds, existing in at least four conformer with internal hydrogen bonds. These last compounds were more rigorously studied at RHF/3-21G^* and RHF/6-31G^** levels. The most stable conformer shows a trans structure for the C=C/P=O angle, with an intramolecular hydrogen bond located between the hydroxylic hydrogen of phosphonic group and the carbonyl oxygen of carboxylic moiety. A secondary conformer is found with a double intramolecular hydrogen bond between two hydroxylic hydrogens of the phosphonic moiety and the oxygen of carboxylic bond. Another secondary conformer appears with an intramolecular hydrogen bond between the oxygen of the phosphoryl bond and the hydroxylic hydrogen of the carboxylic group. A study of the topology of charge densities is carried out. This analysis reveals bonds with an ionic participation. A very weak π conjugation, variable with the conformers, is found in the C=C/P=O system, as well as a strongly polarized P=O partial triple bond. The intramolecular hydrogen bonds give rise to cyclic structures.     

Absence of phosphate hydrolysis in the nucleotide substitution reaction on cis-[Co(H2O)2(cyclen)] at physiological pH: Importance of hydrogen-bonding and conjugate base-catalysis

The use of classical Werner-type cis-[Co(Cl)₂(tetraamine)]⁺ (tetraamine = cyclen or tren) complexes for their complexation study of biologically relevant ligands has been pursued. These chlorocomplexes are found to be in the chloroaqua/chlorohydroxo forms under the physiological conditions used, their chloride substitution reactivity being dominated by conjugate base pathways, specially when tetraamine = cyclen. Further studies with nucleotides indicate that the substitution processes on cis-[Co(H₂O)₂(tetraamine)]³⁺, up to neutral pH, correspond to a simple reaction producing final stable phosphato bound mononucleotide complexes. These complexes are found to be an equilibrium mixture between monodentate O-phosphato and chelate O-phosphato-N-nucleotide forms. No evidence has been found for hydrolytic cleavage of the phosphato-nucleoside bond, as found in other systems with activated phosphates or higher pH values. A full kinetic profile of the process is proposed for the systems in the 2–7 pH range which is the same for chloride, nucleoside and nucleotide substitutions. The results are indicative of an important degree of outer-sphere hydrogen bonding between the cobaltocomplex and the entering biologically relevant ligands, as expected for these processes.     

A totally stereocontrolled route to N-methyl-γ-amino-β-hydroxy acids: Asymmetric synthesis of the amino acid component of hapalosin

A new approach to the synthesis of N-methyl-γ-amino-β-hydroxy acids, compounds that are essential components of several depsipeptides exhibiting highly interesting therapeutic profiles, is presented. Relevant steps in the synthetic sequence involve the totally stereoselective preparation of a protected aminoalkyl epoxide from a highly enantiopure 2,3-epoxy alcohol, efficient N-methylation and three-step conversion to the desired N-methyl amino acid. The method is exemplified by the enantioselective synthesis of (3R,4S)-4-(N-methylamino)-3-hydroxy-5-phenylpentanoic acid in two differently protected forms.     

Stereoselective synthesis of (1R,2S)-2-amino-1,3-diols from (R)-cyanohydrins

Vinyl substituted (1R,2S)-amino alcohols 5 were obtained by addition of vinyl magnesium bromide to the corresponding cyanohydrin O-trimethylsilyl ethers (R)-2. The O- and N-protected vinyl amino alcohols 6 were ozonized at −78°C in methanol yielding (1R,2S)-2-amino-1,3-diols7 in high enantiomeric and diastereomeric excesses. For purification, compounds 7 in some cases were acetylated to give the derivatives (1R,2S)-8. Racemic 6a was converted by oxidative ozonolysis at −78°C in methanolic NaOH solution to the corresponding methyl N-acetyl-β-hydroxy propanoate 9a. The configuration of (1R,2S)-8a was confirmed by x-ray crystallographic analysis.     

ortho-Selective ethylation of phenol with ethanol catalyzed by bimetallic mesoporous catalyst, CoAl-MCM-41

CoAl-MCM-41 (X) catalysts with X = n_Si/(n_Co + n_Al) various ratios were synthesized and ethylation of phenol with ethanol was studied in vapor-phase at temperatures between 250 and 450 °C. The products obtained were O-alkylated product (ethyl phenyl ether), C-alkylated products (2-ethylphenol and 4-ethylphenol), and C-/O-alkylated products (ethyl ethylphenyl ether). The phenol conversion increased significantly with reaction temperature over all the catalysts. The activity of the catalysts followed the order CoAl-MCM-41 (20) > CoAl-MCM-41 (50) > CoAl-MCM-41 (80). Selectivity between the C-alkylation and the O-alkylation depended on the factors such as acidity of the catalyst and the reaction temperature. CoAl-MCM-41 (20) catalyst displayed a phenol conversion of 40% and a selectivity of more than 80% for 2-ethylphenol under the optimized reaction condition. The ethanol to phenol ratios and the reactant flow rate are also influential for both activity and selectivity of CoAl-MCM-41 catalysts.     

Syntheses, crystal structures and electronic properties of a series of copper(II) complexes with 3,5-halogen-substituted Schiff base ligands and their solutions

We have systematically investigated the structural features, electronic properties, thermally-induced structural phase transitions and absorption spectra depending on the solvent for ten Cu(II) complexes with 3,5-halogen-substituted Schiff base ligands. Structural characterization of two new complexes, bis(N-R-1-phenylethyl- and N-R,S-2-butyl-5-bromosalicydenaminato-κ²N,O)copper(II), reveals that they afford a compressed tetrahedral trans-[CuN₂O₂] coordination geometry with trans-N–Cu–N = 159.4(2)° and trans-O–Cu–O = 151.7(3)° for the 1-phenylethyl complex and trans-N–Cu–N = 157.9(3)° and trans-O–Cu–O = 151.0(3)° for the 2-butyl one. All the complexes exhibit a structural phase transition by heating in the solid state regardless of their structures at room temperature. The absorption spectra of a series of ten complexes exhibit a slight shift of the d–d band at 16 000–20 000 cm⁻¹ and remarkable shift of the π–π* band at 24 000–28 000 cm⁻¹, which suggests that the dipole moment of the solvents presumably affects the conformation of the π-conjugated moieties of the ligands rather than the coordination environment. We have also attempted ‘photochromic solute-induced solvatochromism’ by a system of bis(N-R-1-phenylethyl-3,5-dichlorosalicydenaminato-κ²N,O)copper(II) and photochromic 4-hydroxyazobenzene in chloroform solution. We successfully observed a change of the d–d and π–π* bands of the complex in the absorption spectra caused by cis–trans photoisomerization of 4-hydroxyazobenzene.     

Synthesis and application of functional polyethylene graft copolymers by atom transfer radical polymerization

This investigation attempts to elucidate the copolymerization reaction ethylene and p-methylstyrene via the homogeneous metallocene catalyst, Et(Ind)₂ZrCl₂. With increasing of p-methylstyrene concentration, the poly[ethylene-co-(p-methylstyrene)] copolymer shows systematical decrease of melting temperature and crystallinity and increase of glass transition temperature. The benzylic protons of p-methylstyrene are ready for numerous chemical reactions, such as halogenation and oxidation, which can introduce functional groups at the p-methyl group position under mild reaction conditions. With the bromination reaction of poly[ethylene-co-(p-methylstyrene)], polyethylene graft copolymers, such as polyethylene-g-poly(methyl methacrylate) and polyethylene-g-polystyrene can be prepared via atomic transfer radical polymerization. The following selective bromination reaction of p-methylstyrene units in the copolymer and the subsequent radical graft-from polymerization were effective methods of producing polymeric side chains with well-defined structure. The products were characterized by nuclear magnetic resonance, gel-permeation chromatography, differential scanning calorimetry, and thermal gravimetric analysis. Additionally, the morphology of PE/PMMA and PE/PMMA/PE-g-PMMA blend are compared by using scanning electron microscope.     

基于多孔石墨化碳柱-四极杆-飞行时间质谱解析甜菜果胶精细结构

采用高温酸法提取甜菜果胶(SBP), 经强阴离子交换柱层析分离, 获得甜菜果胶水洗脱组分(SBPW)和盐洗脱组分(SBP3). 单糖组成分析和分子量表征结果表明, SBPW主要由半乳糖(Gal)、 阿拉伯糖(Ara)和半乳糖醛酸(GalA)组成, 分子量为1100； SBP3则以GalA为主, 分子量为41450. 通过顺序酶法降解, 应用多孔石墨化碳柱-四极杆-飞行时间质谱(PGC-Triple-Tof MS)联用技术分析鉴定了SBPW和SBP3寡糖的精细结构. 结果表明, SPBW的主链为[→4)-α-GalA-(1→2)-α-Rha-(1→]重复单元构成的Ⅰ型聚鼠李半乳糖醛酸(RG-Ⅰ果胶), 鼠李糖O-4位被中性糖侧链[α-(1→5)阿拉伯聚糖和β-(1→4)半乳聚糖]所取代. SBP3由α-1,4链接的聚半乳糖醛酸(HG)和RG-Ⅰ构成, HG和RG-Ⅰ通过α-1,4糖苷键直接相连, 并发现了α-GalA(1→2)α-Rha(1→4)α-Rha(1→4)α-GalA(1→2)α-Rha的新特征结构.     

New synthetic method to 1,2-benzisothiazoline-3-one- 1,1-dioxides and 1,2-benzisothiazoline-3-one-1-oxides from N-alkyl(o-methyl) arenesulfonamides

Various N-alkylsaccharins were easily prepared in moderate to good yields by the reaction of N-alkyl(o-methyl)arenesulfonamides with (diacetoxyiodo)benzene in the presence of iodine under irradiation with a tungsten lamp (W-hν). On the other hand, irradiation of N-alkyl(o- methyl)arenesulfonamide derivatives bearing various subslituents on the aromatic ring with a high- pressure mercury lamp (Hg-hν), in the presence of (diacetoxyiodo)benzene and iodine gave the corresponding N-alkyl-1,2-benzisothiazoline-3-one-1-oxide derivatives in moderate yields, together with N-alkyl-1,2-benzisothiazoline-3-one-1,1-dioxide (saccharin) derivatives.     

Hydrolysis of amide bond in histidine-containing peptides promoted by chelated amino acid palladium(II) complexes: dependence of hydrolytic pathway on the coordination modes of the peptides

Hydrolytic reactions between cis-[Pd( -Ala-N,O)Cl₂]⁻ and cis-[Pd( -Ala-N,O)(H₂O)₂]⁺, in which -Ala is alanine coordinated through N and O atoms, and N-acetylated peptides -histidylglycine (MeCO-His-Gly), glycyl- -histidine (MeCO-Gly-His), glycylglycyl- -histidine (MeCO-Gly-Gly-His) and glycyl- -histidylglycine (MeCO-Gly-His-Gly) were studied by ¹H NMR spectroscopy. All reactions were carried out in the pH range 2.0–2.5 and two different temperatures, 22 and 60°C. In the reactions of these two palladium(II) complexes with MeCO-His-Gly, complete hydrolysis of the amide bond involving carboxylic group of histidine occurs in less than 24 h. The cleavage is regioselective. With peptides containing free a carboxylic group of histidine, MeCO-Gly-His and MeCO-Gly-Gly-His, palladium(II) complex promote the cleavage of the MeCO–Gly and Gly–Gly amide bonds. No cleavage of the Gly–His amide bond was observed. The mechanism of these hydrolytic reactions involves release of -Ala ligand and aquation of the palladium(II) complex chelated to the substrate through the imidazole N-3 atom and deprotonated nitrogen atom of the amide bond involving amino group of histidine. This aqua complex represents a catalytically active form different from the initially added catalytically inactive complex. In the reactions of palladium(II) complexes with tripeptide MeCO-Gly-His-Gly, two amide bonds, MeCO–Gly and His–Gly, were cleaved. The mechanism of the cleavage of these amide bonds is correlated with two different palladium(II)–substrate catalytically active forms. These findings contribute to the better understanding of selective cleavage of peptides and proteins and must be taken into consideration in designing new reagents for this purpose.     

Photocatalytic removal of the insecticide fenitrothion from water sensitized with TiO2

The photocatalytic removal of the insecticide fenitrothion (IUPAC name: O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), C₉H₁₂NO₅PS, from water suspension of TiO₂, was investigated by following the disappearance of the original substance along with the formation and disappearance of intermediates via recording NMR (¹H and ³¹P) and UV spectra, as well as by pH measurements. Based on the obtained data, a possible reaction mechanism was proposed. It was found that ³¹P-NMR spectrometry can be successfully used to follow the kinetics of transforming organic into inorganic phosphorus in the course of the degradation (k_a=9.2×10⁻⁷ mol dm⁻³ min⁻¹, r=0.980 for the illumination period after 15 h). The rate of fenitrothion aromatic ring decomposition was followed by UV spectrometry during the illumination (k_a=3.1×10⁻⁶ mol dm⁻³ min⁻¹, r=0.989). The complete mineralization was attained after about 66 h of irradiation.     

Decontamination of Chemical Warfare Agents by Novel Oximated Acrylate Copolymer

A novel acrylate copolymer, polymethylacrylate-β-(bromoacetyl ethyl)ester-co-N,N-dimethylacrylamide[P(MABE-co-DMAA)] was synthesized by the copolymerization of N,N-dimethylacrylamide and methylacrylate-β-(bromoacetyl ethyl)ester. Subsequently, the copolymer was oximated by 4-pyridinium aldoxime(4-PAM), and was abbreviated as PAM-P(MABE-co-DMAA). A maximum oxime conversion of 53.7% was obtained. The as-prepared oximated copolymer PAM-P(MABE-co-DMAA) effectively decontaminated chemical warfare agents(CWAs) including methylphosphonofluoridate(sarin or GB), S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate (VX), and 2,2'-dichloroethyl sulfide(sulfur mustard, or HD). The detoxification rates were 90.6% for GB, 85.7% for VX, and 90.5% for HD. Chromogenic analysis, high performance liquid chromatography-mass spectrometry (HPLC/MS) and gas chromatography-mass spectrometry(GC/MS) were used to identify the decontamination products, and the decontamination mechanism was concluded to be a combination of nucleophilic substitution and a second order Beckmann rearrangement. Furthermore, the active decontamination materials, such as decontamination cloths and covers could be made from the oximated copolymer by virtue of its processability, as well as its strong ability to degrade CWA.     

Synthesis and coordination of 2-diphenylphosphinopicolinamide

The synthesis and coordination of 2-diphenylphosphinopicolinamide (dpppa 1) is reported. Coordination complexes with Pd, Pt, Ru, Rh, Ir and Au are described. The ligand behaves as a monodentate P donor in complexes such as [PtCl₂(dpppa-P₂)], [PdCl(allyl)(dpppa-P)], [RuCl₂(p-Cymene)(dpppa-P)], cis-[PtCl₂(dpppa-P)(PR₃)] and [AuCl(dpppa-P)]. Bidentate P, O coordination was accomplished by reaction of BuLi with [RuCl₂(p-Cymene)(dpppa-P)], to give [RuCl(p-Cymene)(dpppa-P,O). P,N donor behaviour was achieved by reaction of a monodentate complex with a halide abstractor [AgBF₄] generating [RuCl(p-Cymene)(dpppa-P,N)][ClO₄] and[RhCl(η⁵-C₅Me₅)(dpppa-P,N)][BF₄]. The X-ray structures of dpppa, dpppaO, dpppaS, four monodentate complexes and [RuCl(p-Cymene)(dpppa-P,O) are reported. All of the structures contain intramolecular N–HN hydrogen bonding.     

质谱法定量测定高密度脂蛋白结合蛋白的糖基化水平

采用质谱法对4种高密度脂蛋白(HDL)的结合蛋白重组人载脂蛋白血清淀粉样蛋白A(SAA)、 α1-抗胰蛋白酶(A1AT)、 α2-人体血清糖蛋白(A2HSG)和A载脂蛋白C3(Apo C3)从蛋白质含量(蛋白的绝对定量)、 位点特异性糖基化(糖肽的相对定量)及聚糖位点占有率等方面进行了研究. 利用四极杆-飞行时间质谱仪(Q-TOF)测量糖蛋白标样酶解产物的二级质谱碎片离子, 用Byonic软件发现了新的糖基化位点信息, 即增加了原位点处聚糖糖型的种类. 对于A2HSG, 新增了N-糖基化156位点上的4种糖型, N-糖基化176位点上的6种糖型, O-糖基化319位点的4种O-聚糖和O-糖基化346位点上的1种糖型. 对于Apo C3, 只有O-糖基化94一个位点, 在此位点上新增了9种糖型. 同时, 调整了用于定量蛋白的多肽, 使得定量更加准确. 采用三重四极杆串级质谱仪(UPLC-ESI-QQQ)研究了4种结合蛋白中多肽和糖肽的多反应监测(MRM)行为, 并重新计算了每种聚糖的位点占有率, 优化了现有的定量方法.     

Methylethers of cinchona alkaloids in Pt-catalyzed hydrogenation of ethyl pyruvate and ketopantolactone: Effect of stereochemical factors on the enantioselectivity

We studied the enantioselective hydrogenation of ethyl pyruvate (EP) and ketopantolactone (KPL) under mild experimental conditions (hydrogen pressure 1 bar, room temperature) on Pt-alumina catalyst modified with O-methyl derivatives of parent cinchona alkaloids (MeOCD, MeOCN, MeOQN, MeOQD) in two solvents with highly different polarities (AcOH, toluene). The best ee's were achieved (91–96%) using MeOCD and MeOQN modifiers in AcOH. Hydrogenation, especially in the presence of the chiral modifiers MeOCN and MeOQD in toluene proceeded with exceptionally low enantioselectivities (35–46% for EP and 2–4% for KPL) as compared to the already well-known Pt-MeOCD catalyst (ee%: 71–74 for EP, 38–48 for KPL). Results of the hydrogenations of the modifiers and studies on the hydrogenation of substrates using modifier mixtures suggested that the low ee are attributable to stereochemical reasons. Namely, it seems justified to suppose that the low ee observed is dependent on the various tilted adsorbed structures of the substrate and modifier 1:1 intermediate complex responsible for enantiodifferentiation.     

Thermal fragmentation and rearrangement of N-arylbenzamidoxime and O-phenylsulfonyloxime derivatives

Thermal fragmentation of N-arylbenzamide oximes I, II (Ar = Ph, p-tolyl) under nitrogen gives rise to benzanilide and 2-phenylbenzoxazole as the major products, in addition to benzonitrile, arylamines, phenols, benzoic acid, o- and p-aminophenols and benzimidazole derivatives. In the presence of naphthalene as radical scavenger, I gave - and β-naphthols beside the previous products. Also, heating N-arylbenzamide O-phenylsulfonyloximes III under reflux in boiling tetralin lead to the formation of benzonitrile, arylamines, diphenylamine, benzenesulfonic acid, diphenyl sulfone, 1-hydroxytetralin, -tetralone, and 1,1′-bitetralyl as the major products. Analogous results are obtained on heating III in the presence of isoquinoline as a radical trap which formed 1-phenylisoquinoline. The isolated products have been interpreted in terms of a free radical mechanism involving the homolysis of NO and/or CN bonds.     

人肝癌细胞HepG2与正常肝细胞L02的O-糖链的比较分析

以培养的原发性肝细胞癌HepG2细胞和正常肝细胞L02为研究对象, 用细胞裂解液提取总蛋白, 然后采用Carlson还原性β-消除法释放O-糖链, 以阳离子交换柱结合C₁₈柱纯化分离O-糖链, 用电喷雾电离质谱(ESI-MS)和串联质谱(MS/MS)对O-糖链进行序列鉴定, 以β-环糊精为内标对2种细胞系的O-糖链进行定量比较分析. 结果表明, 在肝癌细胞系HepG2中检测到10种O-糖链, 正常细胞系L02中检测到9种O-糖链, 其中9种O-糖链是2种细胞系中共有的, 但HepG2中存在癌细胞中特有的缩短的O-糖链N1A1(NeuAc-GalNAc, sialyl Tn 抗原). t检验结果表明, HepG2与L02相比, 在检测到的10种O-糖链中有5种的含量具有极显著性差异(P<0.01), 2种的含量具有显著性差异(P<0.05).