Tb3+离子发光探针研究Ca2+,La3+和Al3+与拟南芥钙调素的竞争结合

利用Tb3 离子的发光, 研究了Tb3 与拟南芥钙调素 (CaM)结合的荧光光谱及荧光滴定曲线特点, 然后利用Tb3 4*CaM系统在221 nm直接激发和280 nm敏化激发的光谱变化研究了Ca2 , La3 和Al3 与拟南芥钙调素 (CaM) 的竞争结合作用. 结果表明: Tb3 , La3 与钙调素的竞争结合能力强于Ca2 , 而Tb3 的竞争结合力又大于La3 , Ca2 与钙调素的结合力远大于Al3 . 竞争实验的结果从分子水平上揭示了Tb3 , La3 和Al3 等金属离子生物效应可能的分子机制.     

Raman spectroscopy of CaM2+Ge2O6 (M2+ = Mg,Mn, Fe,Co, Ni,Zn) clinopyroxenes

The Raman spectra of Ge‐clinopyroxenes CaM²⁺Ge₂O₆ (M²⁺ = Mg, Mn, Fe, Co, Ni, Zn), general formula M2M1T₂O₆, are reported for the first time. Their spectral features are discussed in comparison with corresponding Si‐pyroxenes. The vibrational wavenumbers of germanates may be roughly obtained by a scale factor of about ~0.8 by those of the corresponding silicates, due to the Ge‐Si mass difference. The main peaks in the germanate Raman spectra at ~850 and ~540 cm⁻¹ may be related to Ge‐O tetrahedral stretching and chain bending, respectively; minor peaks between 200 and 400 cm⁻¹ are ascribed to bending and stretching of the non‐tetrahedral cations. Within Ge‐pyroxenes, possible correlations between crystallographic parameters and the vibrational wavenumbers are investigated. The main stretching mode at ~850 cm⁻¹ shows wavenumber changes with M²⁺ substitutions, but no simple correlation can be found with M²⁺ cation mass or size. On the other hand, the chain bending wavenumber linearly decreases with increasing ionic radius of the M²⁺ cation: the expansion of the M1 polyhedron reduces the chain kinking angle and the Ge‐Ge distances correspondingly increase. Copyright © 2015 John Wiley & Sons, Ltd.     

硝酸铈对钙调素及调节蛋白Ca~(2 )-ATP酶基因表达的影响

运用逆转录聚合酶链式反应研究了硝酸铈对大白鼠肝脏CaMⅠ ,PMCA1b基因表达的影响。腹腔注射高、低浓度硝酸铈均不会引起CaMⅠ ,PMCA1b基因表达的变化 ,提示硝酸铈对钙调素、Ca2 ATP酶的影响可能仅处于转录后水平。     

HPGMR叶片中Ca2+/CaM依赖性蛋白激酶的初步研究

以 HPGMR农垦 5 8S为材料 ,研究了光周期处理前、后 Ca2 /Ca M依赖性蛋白激酶 (Ca2 /Ca M- PK)活性及其酶谱特征 .结果表明 :随着幼穗的发育 ,Ca2 /Ca M- PK活性均有提高 ,并且长日照和自然日照条件下的酶活提高程度大大高出短日照处理 .不同时期、不同处理的 Ca2 /Ca M- PK酶谱带数未见明显差异 ,但在总体上 ,不育植株 (L D和 ND)的酶带弱于可育植株 (SD)     

植物钙调素与Ce3+离子结合反应的荧光光谱法研究

水合Ce^3＋离子发射强荧光,而用Ce^3＋滴定植物钙调素（CaM）时,Ce^3＋离子荧光被完全淬灭,据此建立了测定Ce^3＋离子与植物钙调素结合位点数及逐级结合常数的方法。实验表明,Ce^3＋离子与植物钙调素的荧光激发光谱及发射光谱形状与光谱强度都有显著差别,前者的荧光强度远大于后者,故CaM存在时可以测定游离Ce^3＋的浓度。Ce^3＋离子荧光淬灭法测定结果说明,在0.5 mol·L^-1KCl溶液中,CaM有4个Ce^3＋离子结合位点。进一步通过Ce^3＋滴定植物钙调素的实验,并结合Excel规划求解法,计算出Ce^3＋与CaM的结合常数,K1=4.17×10^7,K2=1.26×10^7,K3=1.89×10^6,K4=2.04×10^6。     

水稻叶片Ca~(2 )/CaM依赖性蛋白激酶的纯化和活性测定

通过高速离心、( NH4) 2 SO4沉淀、琼脂糖凝胶过滤和 Ca M- sepharose4B亲和层析 ,从 HPGMR( 5 8S)叶片中初步纯化出 Ca2 / Ca M依赖性蛋白激酶 .纯化的 Ca2 / Ca M依赖性蛋白激酶经 SDS-聚丙烯酰胺凝胶线性梯度电泳 ,亚基分子量约为 5 5× 10 3.在 Ca2 / Ca M依赖性蛋白激酶的标准反应体系中 ,存在过量的 ATP,提取磷酸化反应剩余的 ATP,用叶绿体 Mg2 - ATP酶分解 ATP,最后用复合孔雀绿测定无机磷 ,从而来计算 Ca2 / Ca M依赖性蛋白激酶的活性 .实验结果表明 ,该酶活性是依赖 Ca2 和 Ca M的 ,并且 EGTA和 TFP对酶活性有明显的抑制作用     

离子选择电极法研究钙调素与重金属铅的结合平衡

用Pb2 选择电极法首次测定了CaM与Pb2 的结合常数,结果说明:Pb2 在CaM中约有10个结合位点,与文献报道的一致。其中包括4个强结合位点,结合常数在107量级,对应于Pb2 在CaM中的4个主结合位点;而其余的位点则结合常数较低,对应于Pb2 在CaM中的约6个辅助结合位点。逐级结合常数分别为:K1=2.62×107,K2=3.75×107,K3=1.03×107,K4=1.85×107,K5=2.53×106,K6=8.07×105,K7=3.36×105,K8=2.76×105,K9=2.22×105,K10=3.96×104。由于Pb2 与CaM的4个主结合位点的稳定常数比相应Ca2 的强几十到几百倍,因此Pb2 对Ca2 与CaM的竞争结合作用能够调节CaM的功能。     

Silicon nanowires as field-effect transducers for biosensor development: A review

The unique electronic properties and miniaturized dimensions of silicon nanowires (SiNWs) are attractive for label-free, real-time and sensitive detection of biomolecules. Sensors based on SiNWs operate as field effect transistors (FETs) and can be fabricated either by top–down or bottom–up approaches. Advances in fabrication methods have allowed for the control of physicochemical and electronic properties of SiNWs, providing opportunity for interfacing of SiNW-FET probes with intracellular environments. The Debye screening length is an important consideration that determines the performance and detection limits of SiNW-FET sensors, especially at physiologically relevant conditions of ionic strength (>100 mM). In this review, we discuss the construction and application of SiNW-FET sensors for detection of ions, nucleic acids and protein markers. Advantages and disadvantages of the top–down and bottom–up approaches for synthesis of SiNWs are discussed. An overview of various methods for surface functionalization of SiNWs for immobilization of selective chemistry is provided in the context of impact on the analytical performance of SiNW-FET sensors. In addition to in vitro examples, an overview of the progress of use of SiNW-FET sensors for ex vivo studies is also presented. This review concludes with a discussion of the future prospects of SiNW-FET sensors.     

Impedance Characterization of Adsorption Process of Calmodulin on Au Substrate and its Combination with Ca~(2+)

Recently, the adsorption behavior of protein on solid substrate has attracted much attention for the reason that adsorption on a substrate is the first key step for other further electrochemical investigation1. Meanwhile the free adsorption could provide a relative well-ordered structure, with which some fundamental study could be carried out conveniently2. As we know, the electrochemical impedance spectroscopy (EIS) method has become one of the powerful techniques to detect the change of i…