荧光光谱法研究荧光桃红与牛血清白蛋白的相互作用

分别用荧光光谱法、分光光度法研究了水溶液中荧光桃红(TCBF)与牛血清白蛋白(BSA)的结合反应。研究表明,BSA与TCBF的结合数为n=1.16。其平衡常数KA=6.95×106L/mol。根据F rster非辐射能量转移理论,求算了给体(BSA)受体(TCBF)间的距离r=1.79 nm和能量转移效率E=0.83。实验表明:荧光桃红与牛血清白蛋白的相互结合作用为单一的荧光静态猝灭过程。     

孔雀石绿与牛血清白蛋白作用的光谱研究

应用荧光及紫外光谱法研究了孔雀石绿(MG)与牛血清白蛋白(BSA)相互作用的光谱特性。测定了16℃、26℃、36℃三个温度下的结合常数KA(7.066×103、4.638×103、1.338×103)和结合位点数n(1.2、1.1、1.0)。结果表明:MG对BSA内源荧光的猝灭机理主要为静态猝灭;MG主要以范德华力与BSA相互作用;同步荧光技术研究了MG对BSA构象的影响,表明BSA的荧光主要源于色氨酸残基,MG对BSA的构象有影响;利用F ster偶极-偶极非辐射能量转移理论,计算了三个温度下MG与BSA的作用距离(r16℃=3.30,r26℃=3.314,r36℃=3.58nm),表明MG对BSA的荧光猝灭中存在能量转移。     

荧光光谱法研究左西孟旦与牛血清白蛋白的结合反应

用荧光光谱法、分光光度法研究了水溶液中左西孟旦与牛血清白蛋白(BSA)的相互结合反应。研究表明:左西孟旦对BSA的内源荧光有较强的猝灭作用且该猝灭作用属于静态荧光猝灭作用。得出了反应的结合常数(KA=1.48×106L/mol)和结合位点数(n=1.14)。根据Frster非辐射能量转移机理,求算了给体(BSA)与受体(左西孟旦)间距离r=2.9 nm和能量转移效率E=0.33。     

绞股蓝皂苷与牛血清白蛋白相互作用的荧光光谱研究

用荧光光谱技术研究了绞股蓝皂苷与牛血清白蛋白(BSA)在pH=7.40的Tris-HCl缓冲溶液中的相互作用;通过计算确定了绞股蓝皂苷与BSA的结合位点数和结合常数,利用热力学分析探讨了绞股蓝皂苷与BSA之间的结合方式;同时采用同步荧光技术考察了绞股蓝皂苷对BSA构象的影响.结果表明,绞股蓝皂苷对牛血清白蛋白的荧光猝灭过程为静态猝灭;二者主要靠疏水作用和静电引力结合.     

锌离子对缓冲液中槲皮素和牛血清白蛋白相互作用的影响

采用荧光光谱法和紫外光谱法研究了Zn2+离子对槲皮素(Qct)和牛血清白蛋白(BSA)在pH=7.4的Tris-HCl缓冲溶液中相互作用的影响;根据荧光猝灭双倒数图计算了Qct和BSA之间的结合常数和结合位点数.结果表明,Qct和Zn2+离子都可以使BSA的荧光强度发生猝灭;Qct和BSA之间的结合常数为3.17×107L.mol-1.s-1,结合位点数为1.32.定量计算表明,加入Zn2+离子后,Qct与BSA间的结合常数显著降低、结合位点数减小,表明Zn2+离子参与了Qct与BSA的结合过程.     

应用荧光光度法研究3,5-二溴水杨醛缩牛磺酸席夫碱与牛血清白蛋白相互作用

应用紫外分光光度法和荧光光度法研究了3,5-二溴水杨醛缩牛磺酸席夫碱(DSTSB)在pH3.2的介质中,与牛血清白蛋白(BSA)的相互作用(结合作用),考察了DSTSB对BSA构象的影响。讨论了DSTSB对BSA内源荧光的淬灭机理,测得猝灭常数Kq=2.1×1014L.mol-1.s-1,结合常数(KA=6.31×108L.mol-1)和结合点位数(n=1.1725)。依据Frester辐射能量转移理论确定了荧光给体-受体间距离(r=3.67nm)。     

邻苯二甲酸二乙酯与牛血清白蛋白相互作用的光谱学研究

采用荧光光谱法与紫外光谱法研究了邻苯二甲酸二乙酯(DEP)与牛血清白蛋白(BSA)之间的相互作用机制。荧光猝灭结果表明,在模拟生理条件(pH=7.4)下,DEP对BSA主要为静态猝灭过程;298 K时的结合常数与结合位点数分别为2.69×10~4 L·mol~(-1)和0.93;热力学参数焓变(ΔH)与熵变(ΔS)均为正数,说明DEP与BSA之间主要为疏水作用力。依据F?rster非辐射能量转移理论求得DEP与BSA之间的结合距离为2.12nm,两者之间极有可能发生非辐射能量转移,由紫外光谱、同步荧光光谱和三维荧光光谱实验结果可知DEP诱导BSA分子构象发生变化。     

小檗碱与牛血清白蛋白相互作用的光谱研究

利用紫外光谱和荧光光谱研究了中药有效成分小檗碱与牛血清白蛋白(BSA)的相互作用机制。利用荧光猝灭反应测得它们之间结合常数K=1.49×105L/mol,结合位点数n=9.77,依据F rster非辐射能量转移机制,测得供体 受体间结合距离R=3.09nm和能量转移效率E=0.443。认为小檗碱在BSA的位置阻断了酪氨酸残基与色氨酸残基之间的能量转移,导致BSA的荧光猝灭。     

荧光光谱法研究染料木苷与牛血清白蛋白的相互作用

采用荧光光谱法,在pH=7.4的磷酸盐缓冲溶液(PBS)中研究了染料木苷(Genistin,Ge)与牛血清白蛋白(BSA)的作用方式及作用机理.结果表明,Ge可静态猝灭BSA的内源荧光,二者之间的结合位点数为1.4,温度对结合常数影响不大,300K、306 K、310 K和313 K的结合常数平均为4.31×104 L...     

荧光光谱法结合多元曲线分辨-交替最小二乘法研究伞形花内酯与牛血清白蛋白的相互作用

在模拟人体生理条件下(pH=7.4), 用荧光光谱法结合多元曲线分辨-交替最小二乘法(MCR-ALS)研究伞形花内酯与牛血清白蛋白(BSA)的相互作用. 采用两种不同的试剂滴加模式对伞形花内酯与BSA的相互作用进行研究, 对经典的荧光光谱数据矩阵加以扩展, 增加了实验数据的信息量; 进而应用MCR-ALS对该扩展的荧光光谱矩阵进行迭代计算, 较好地分辨出作用过程中浓度变化趋势图, 并计算出伞形花内酯与BSA的表观结合常数和结合比. 通过同步荧光光谱法发现伞形花内酯对BSA的构象有一定的影响.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.