Effects of extracellular calmodulin on pollen germination and tube growth

The effects of calmoddin (CaM) antagonist W7-agarose, anti-CaM serum and exogenous purified CaM on pollen germination and tube growth ofForsythia suspensu were studied. The pollen germination and tube growth were inhibited or completely stopped by CaM antagonist W7-agarose. The addition of exogenous purified CaM stimulated pollen germination and tube growth, whereas the same amount of bovine serum albumin (BSA) had no effect. The inhibitory effects caused by W7-agarose and anti-CaM serum could be reversed completely by the addition of exogenous purified CaM. The tube growth of germinated pollen was also inhibited or completely stopped by W7-agarose. The results suggest that endogenous extracellular CaM initiates pollen germination and tube growth, whereas exogenous CaM enhances the above processes.     

铕对小麦根细胞钙调素及NAD激酶的影响研究

研究了Eu对小麦根细胞内钙调素的含量和活性以及对受钙调素调控的专一性酶NAD激酶的影响。结果表明，Eu^3＋有类似Ca^2＋的作用，影响受Ca^2＋浓度调控的信号系统关键蛋白——钙调素的活性和含量变化。从而引起钙调素调控酶NAD激酶的活性改变，最终影响细胞内生理生化过程。认为稀土离子对生物体的Hormesis效应町能与稀土离子对细胞信号传递系统的影响有关，稀土离子可能通过影响细胞信号系统来调节细胞内的各种生理生化变化，形成稀土元素生物效应的多样性特征。     

Binding Sites of La~(3 ) on Camodulin

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CHARMM36 all‐atom additive protein force field: Validation based on comparison to NMR data

Protein structure and dynamics can be characterized on the atomistic level with both nuclear magnetic resonance (NMR) experiments and molecular dynamics (MD) simulations. Here, we quantify the ability of the recently presented CHARMM36 (C36) force field (FF) to reproduce various NMR observables using MD simulations. The studied NMR properties include backbone scalar couplings across hydrogen bonds, residual dipolar couplings (RDCs) and relaxation order parameter, as well as scalar couplings, RDCs, and order parameters for side‐chain amino‐ and methyl‐containing groups. It is shown that the C36 FF leads to better correlation with experimental data compared to the CHARMM22/CMAP FF and suggest using C36 in protein simulations. Although both CHARMM FFs contains the same nonbond parameters, our results show how the changes in the internal parameters associated with the peptide backbone via CMAP and the χ₁ and χ₂ dihedral parameters leads to improved treatment of the analyzed nonbond interactions. This highlights the importance of proper treatment of the internal covalent components in modeling nonbond interactions with molecular mechanics FFs. © 2013 Wiley Periodicals, Inc.     

Application of plug–plug technique to ACE experiments for discovery of peptides binding to a larger target protein: A model study of calmodulin‐binding fragments selected from a digested mixture of reduced BSA

To discover peptide ligands that bind to a target protein with a higher molecular mass, a concise screening methodology has been established, by applying a “plug–plug” technique to ACE experiments. Exploratory experiments using three mixed peptides, mastoparan‐X, β‐endorphin, and oxytocin, as candidates for calmodulin‐binding ligands, revealed that the technique not only reduces the consumption of the protein sample, but also increases the flexibility of the experimental conditions, by allowing the use of MS detection in the ACE experiments. With the plug–plug technique, the ACE–MS screening methodology successfully selected calmodulin‐binding peptides from a random library with diverse constituents, such as protease digests of BSA. Three peptides with K_d values between 8–147 μM for calmodulin were obtained from a Glu‐C endoprotease digest of reduced BSA, although the digest showed more than 70 peaks in its ACE–MS electropherogram. The method established here will be quite useful for the screening of peptide ligands, which have only low affinities due to their flexible chain structures but could potentially provide primary information for designing inhibitors against the target protein.     

不同pH值对Au/CaM膜结合Ca2+的电化学行为研究

采用交流阻抗的方法,在包含1 mmol/L Fe(CN)63-/4-的0.15 mol/L的NaCl溶液中,研究了Au/CaM膜在不同的酸碱环境下结合Ca2 的电化学行为.结果表明:在pH为6.5的环境下Au/CaM膜结合Ca2 的能力要比在pH为4.5环境下的强.     

Au/CaM自组装膜方波伏安法表征

采用方波伏安法,在包含1 mmol/L[Fe(CN)6]3-/[Fe(CN)6]4-的0.15 mol/L的NaCl溶液中,对Au/CaM膜的电化学行为进行了初步表征。由方波伏安电流响应图可知:CaM可以在Au基底自组装成膜,[Fe(CN)6]3-/[Fe(CN)6]4-在Au/CaM膜电极上发生的是电化学不可逆反应过程。     

钙调蛋白抑制剂预测模型研究

选用30个结构多样的caM抑制剂分子作为数据集,采用多元线性回归(MLR)方法及主成分回归分析(PCA)方法对每个化合物的194个分子参数进行回归分析,分别建立了各自的最优预测模型.结果表明:多元线性回归分析方法所建模型与主成分回归所建模型相对比,发现逐步筛选法为最优建模方法?该方法所建模型统计结果良好(R2=0.952,SEE为0.289),应用于检验集时结果也比较令人满意(R2=0.941,SEP为0.295),模型表现出较强的可靠性和预测性.