乙基罗丹明B-磷钒钼杂多酸-PVA体系超高灵敏显色反应的研究及应用

研究了乙基罗丹明B 磷钒钼杂多酸 PVA体系超高灵敏显色反应的适宜条件、灵敏度和选择性 ,及在实际工作中的应用。缔合物的最大吸收波长为 5 86nm ,表观摩尔吸光系数为 1.4×10 5L·mol- 1·cm- 1。方法用于钢铁、化学试剂和铬铁矿等中痕量磷的直接测定 ,结果满意     

New palladium (II) complexes containing phosphine‐nitrogen ligands and their use as catalysts in aminocarbonylation reaction

Aminocarbonylation of aryl halides, homogeneously catalysed by palladium, is an efficient method that can be employed for obtaining amides for pharmaceutical and synthetic applications. In this work, palladium (II) complexes containing P^N ligands were studied as catalysts in the aminocarbonylation of iodobenzene in the presence of diethylamine. Two types of systems were used: a palladium (II) complex formed in situ; and one prepared prior to the catalytic reaction. In general, the palladium complexes studied achieved high conversions in an average reaction time of less than 2 hr, which is less than that for the standard system (Pd (II)/PPh₃) used. The pre‐synthesized complexes were faster than their in situ counterparts, as the latter require an induction time to form the Pd/P^N species. The structure and electronic properties of the ligand P^N can influence both the activity and the selectivity of the reaction, stabilizing the acyl‐palladium intermediates formed in a better manner.     

Fibrous and helical calcite crystals induced by synthetic polypeptides containing o-phospho-L-serine and o-phospho-L-threonine

The modification of CaCO(3) crystal growth by synthetic L-Ser(PO(3)H(2)) and L-Thr(PO(3)H(2)) containing polypeptides is described. The amino acids Gly, L-Glu, L-Asp, L-Ser, L-Ala, and L-Lys induced rhombohedral calcite with a rough surface. Dipeptides, Xaa-L-Ser(PO(3)H(2)) (Xaa = Gly, L-Glu, L-Asp, L-Ser, L-Ala and L-Lys) induced vaterite crystals in the lower [Ca(2+)]. On the other hand, L-Ser(PO(3)H(2))-containing polypeptides formed spherical vaterite and fibrous calcite. The characteristic helical calcite was found in the presence of copoly[L-Ser(PO(3)H(2))(75)L-Asp(25)] or poly[L-Ser(PO(3)H(2))(3)-L-Asp]. Fibrous calcite, spherical vaterite, and helical calcite crystals were subjected to XRD and EDX analysis. XRD revealed the specific faces of these crystals. EDX spectra and surface analysis visualized the localization of the polypeptides and CaCO(3) components. Together with TEM and SAED data, we propose hypothetical growth mechanisms for the fibrous and helical calcite crystals.     

Synthesis of collagen-like sequential polypeptides containing O-phospho-L-hydroxyproline and preparation of electrospun composite fibers for possible dental application

A synthetic route is described for collagen-like polypeptides constructed from O-phospho-L-hydroxyproline [Hyp(PO(3)H(2))] residues. Using the synthetic polypeptides and a natural protein, gelatin, fine fibers and their network structures (ESNWs) were prepared via electrospinning. The composite ESNWs can induce the mineralization of calcium phosphate. The phosphoryl groups of the Hyp(PO(3)H(2)) residues affect both the crystalline phase and amount of the calcium phosphate, depending on the chemical structure in the repeating sequence. The composite ESNWs can be developed as a biocompatible replacement of the extracellular matrix of hard tissues, and thus can be applied as dental materials for restoration of dental cavities or as a sealant for pits and fissures.     

磷钨酸催化合成丙烯酸丁酯

用磷钨酸为催化剂 ,由丙烯酸和丁醇直接酯化合成了丙烯酸丁酯。研究了醇 /酸比、酯化时间、催化剂用量、带水剂用量对酯化率的影响 ;选择了最佳反应条件 ,重复反应酯化率达到 95 %以上。     

Phospho‐l‐tyrosine‐agarose chromatography: Adsorption of human IgG and its proteolytic fragments

The behavior of human immunoglobulin G (IgG) and antigen‐binding fragment (Fab fragment) adsorption onto phospho‐l ‐tyrosine immobilized on agarose (P‐Tyr‐agarose) was evaluated by pseudoaffinity chromatography. The effects of buffer systems MES, MOPS, Bis–Tris, Tris–HCl and sodium phosphate (NaP) and pH on IgG adsorption were studied and high purity values were obtained (96%, based on ELISA analysis of albumin, transferrin and immunoglobulins A, G and M) when IgG was purified from human plasma diluted in 10 mmol L^?1 NaP buffer at pH 6.0. The capture of IgG by the P‐Tyr‐agarose was also promising, since 91% of the IgG was adsorbed when plasma was diluted in 25 mmol L^?1 MES buffer at pH 5.5, recommending its use for IgG depletion from human plasma under this condition. The experimental data on IgG adsorption kinetics were in agreement with the pseudo‐second‐order model. The adsorption isotherm data were well described by the Langmuir–Freundlich model with the value of parameter n being <1 (0.72), indicating negative cooperativity. Selectivity was achieved on P‐Tyr‐agarose from digested human IgG in HEPES 25 mmol L^?1 buffer at pH 7.0 where Fab fragments were obtained in eluted fractions without Fc fragments (but with uncleaved IgG) with 86.2% recovery.     

Large‐volume sample stacking with polarity switching for monitoring of nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) reactions by capillary electrophoresis

Nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) is a membrane glycoprotein involved in the hydrolysis of extracellular nucleotides. Its main substrate is ATP yielding AMP and pyrophosphate. NPP1 has been proposed as a novel drug target, for diabetes type 2 and the treatment of calcium pyrophosphate dihydrate deposition disease leading to inflammatory arthritis. The monitoring of NPP1 reactions is difficult because its velocity is very slow requiring highly sensitive analytical procedures. In this study, a method of large‐volume sample stacking with polarity switching was developed, and separations were optimized. Large sample volumes were loaded by hydrodynamic injection (5 psi, 13 s) followed by removal of a large plug of sample matrix from the capillary using polarity switching (?10 kV). The stacked analytes were subsequently separated in phosphate buffer (100 mM, pH 9.2) at 20 kV. The validated method was found to be linear (R² = 0.9927) in the concentration range of 0.05–50 μM of AMP, with high accuracy and precision. The determined LOD and LOQ of AMP were 18 nM and 60 nM, respectively. Compared to a previously reported CE procedure using sweeping technique, a fivefold improvement of sensitivity was achieved. Moreover, the new technique was faster, and reproducibility of migration times was improved (RSD value = 1.2%). Importantly, adenine nucleotide analogs and derivatives tested as NPP1 inhibitors could be completely separated from the substrate ATP and the enzymatic product AMP. The method was applied to NPP1 inhibition assays investigating nucleotide‐derived inhibitors in the presence of ATP.     

Preparation and adsorption properties of phospho‐L‐glutamic acid on hydroxyapatite

Phospho‐L‐glutamic acid was successfully prepared by the phosphorylation of glutamic acid, and its adsorption on synthetic hydroxyapatite (HAP) was studied together with glutamic. The adsorption behaviors of both adsorbates were adequately described by a Langmuirian model. From the comparison between two different adsorbates, the results of the investigation indicated that the phosphate group in phospho‐L‐glutamic acid can greatly enhanced the adsorption affinity for HAP, the improvement of which was achieved through replacing the same group on the surface of HAP and interacting with the surface calcium ion of HAP by electrostatic attraction. The results obtained laid the solid foundation for further research on the regulating function of phosphorylated amino acids with hydroxyapatite biological composites. Copyright © 2010 John Wiley & Sons, Ltd.     

对叔丁基杯[8]芳烃/12-钨(钼)磷(硅)杂多酸超分子包合物的合成与性质

用自识别自组装法合成了三种新型对叔丁基杯[8]芳烃/12-钨(钼)磷(硅)杂多酸超分子包合物,C88H115～116O8[XM12-040](X=P,Si;M=w,Mo),用元素分析,IR,UV,1H NMR,31P NMR,ESR,XPS,Fluorescence光谱进行了表征.结果表明,对叔丁基杯[8]芳烃主体化合物与12-钨(钼)磷(硅)杂多酸客体分子发生了主-客体包合反应,生成了稳定的发光包合物.     

Random and sequential copolypeptides containing O-phospho-L-threonine and L-aspartic acid; roles in CaCO3 biomineralization

The present study describes the synthesis of novel polypeptides containing O-phospho-L-threonine [Thr(PO(3)H(2))] and L-aspartic acid. Random copolypeptides copoly[Thr(PO(3)H(2))(X)Asp(Y)] (X:Y = 25:75, 50:50, 75:25), were conventionally prepared by copolymerization of Thr(PO(3)Ph(2)) N-carboxyanhydride (NCA) and Asp(OBzl) NCA followed by deprotection of the phenyl and benzyl groups by catalytic hydrogenolysis over PtO(2). Polycondensation of the protected peptide p-nitrophenyl esters [Thr(PO(3)Ph(2))](Z)-Asp(OBzl)-ONp and subsequent deprotection yielded the sequential polypeptides poly[Thr(PO(3)H(2))(Z)-Asp] (Z = 1-4). By using the synthetic polypeptides, their effects on the growth of CaCO(3) crystals were examined. In the poly[Thr(PO(3)H(2))(Z)-Asp]/CaCO(3) systems, brushlike calcite and spherical vaterite were formed, with the former being found at [Ca(2+)]/[Res] ratios of > or =180, > or =140, > or =120, and > or =100 for Z = 1, 2, 3, and 4, respectively. These results indicate that an increase of Thr(PO(3)H(2)) residues in the repetitive unit induces the characteristic brushlike calcite, a fact indicating that Thr(PO(3)H(2)) residues can modify the CaCO(3) crystal morphology.