Non-covalent interaction between almond protein and sinapic acid: impact on protein structure and antioxidant activity

Plant phenolic acids are good sources of antioxidants and sinapic acid(SA)is one of them that can be applied in protein-based food system.However,little research is available regarding interactions between almond protein(AP)and SA.In this study,structure-affinity interaction between SA and AP,structure and antioxidant activity of proteins were investigated.Different mathematical models showed that Ka of binding SA and AP were 3.27×10^4 L/mol and 3.08×10^4 L/mol.CD(Circular dichroism)spectroscopy and FT-IR(Fourier transform infrared)spectroscopy showed that the amount of random coil andα-helix decreased whileβ-sheet increased in AP-SA complex.In combination,the interaction model of AP-SA complex was static quenching and attributed to hydrophobic interaction.Further,AP-SA complex exerted better DPPH radical scavenging ability(36.97±0.78%),ABTS+radical scavenging ability(47.26±0.45%),and higher ORAC value(2.41±0.23 M trolox/g)compared to AP.In the further,SA can be applied in protein matrix to improve film stability,gel strength and restraining fat oxidation degradation.

Effects of 4PU-30 on leaf senescence and degration of protein and nucleic acid in rice

4PU—30[N—phenyl—’N—(2—chloro—4—pyridyl) urea] is a new type of plant growth regulator with cytokinin properties. It has been confirmed to delay rice leaf senescence effectively. In order to elucidate the physiological role of 4PU—30 in delaying senescence, the changes of protein, nucleic acid contents, and the related activities of degradative enzymes were studied. Shanyou 63, an indica hybrid rice was used for this experiment. In the in vitro experiment, two full—developed leaves from the top during heading stage were collected and cut into 5.0cm segments, They were floated on the surface of distilled water containing 0.1mg/14PU—30 and incubated in darkness at 30 C. The leaves floated on distilled water were used as control.It was observed that chlorophyll content in controlled leaves declined rapidly started from the second day and dropped by 93.4% on the 6th day while that in leaves treated with 4PU—30 declined by 41.4% only. During senescence, specific activities of hemoglobin—digesting

Evaluation on performance of MM/PBSA in nucleic acid-protein systems

The molecular mechanics/Poisson-Boltzmann surface area(MM/PBSA) method has been widely used in predicting the binding affinity among ligands,proteins,and nucleic acids.However,the accuracy of the predicted binding energy by the standard MM/PBSA is not always good,especially in highly charged systems.In this work,we take the protein-nucleic acid complexes as an example,and showed that the use of screening electrostatic energy(instead of Coulomb electrostatic energy) in molecular mechanics can greatly improve the performance of MM/PBSA.In particular,the Pearson correlation coefficient of dataset Ⅱ in the modified MM/PBSA(i.e.,screening MM/PBSA) is about 0.52,much better than that(<0.33)in the standard MM/PBSA.Further,we also evaluate the effect of solute dielectric constant and salt concentration on the performance of the screening MM/PBSA.The present study highlights the potential power of the screening MM/PBSA for predicting the binding energy in highly charged bio-systems.

Interaction of Immune System Protein with PEGylated and Un-PEGylated Polymeric Nanoparticles

Biodegradable Nanoparticles (NPs) are under intense investigation due to their potential application in targeted drug delivery. Upon their entry to the biological system, they encounter the immune system, which limits their availability at the intended site. Most importantly, the innate immune system is the one that acts as the first line of defense against foreign materials. It can be activated by collectin proteins which recognize the structural pattern of polysaccharide on the surface of microorganisms. NPs may interact with these proteins in a similar way, and the interaction may lead to beneficial outcomes in vaccine delivery. On the other hand, in targeted drug delivery, it is desirable for the NPs not to be recognized as foreign material as this may lead to their fast elimination from the system through mechanism such as opsonization. We investigated the interaction of PEGylated and un-PEGylated PLGA NPs with Recombinant Human Mannose-Binding Protein (HMBP) in an effort to understand the effect of surface modification on their binding to the protein. Results show that both PLGA-COOH and PLGA-PEG-NH2 bind to HMBP as studied using dynamic light scattering (DLS), fluoresce and UV-vis spectroscopy. However, their binding is shown to have different effect on the structure of the protein. Study done using fluorescence spectroscopy displayed a decrease in fluorescence emission of the protein upon binding to PLGA-COOH. On the other hand the fluorescence emission of the protein increased upon binding to the PLGA-PEG-NH2 indicating conformational changes in the protein structure.

Cold Acclimation-Induced Changes in Total Soluble Protein, RNA, DNA, RNase and Freezing Resistance in Populus tomentosa Cuttings

The changes in the contents of total soluble protein and RNA, the activity of RNase in leaves and branches of Populus tomentosa cuttings at various periods (viz: cold acclimation, deacclimation, chilling stress and the recovery after chilling stress), and the survival rate and the freezing resistance of cuttings during cold acclimation at -3℃ were investigated. Results showed that cold acclimation not only increased the contents of total soluble protein and RNA, the survival rates and the freezing resistance of cuttings, decreased the activity of RNase, but also reduced the declining degree of total soluble protein and RNA contents, and the increasing level of RNase caused by chilling stress as compared with the controls. In addition, cold acclimation augmented the increase in the level of total soluble protein and RNA, and facilitated the decrease of RNase during the recovery periods. Further analysis found that the DNA content of all treatments kept relative stability at various periods. The changes in total soluble protein, RNA and RNase were closely related to the freezing resistance of cuttings. It appears that the increase of RNA content caused by cold acclimation induced decrease of RNase activity may be involved in the accumulation of total soluble protein and the induction of freezing resistance of cuttings.

Gene environment interaction in periphery and brain converge to modulate behavioral outcomes:Insights from the SP1 transient early in life interference rat model

It is generally assumed that behavior results from an interaction between susceptible genes and environmental stimuli during critical life stages.The present article reviews the main theoretical and practical concepts in the research of gene environment interaction,emphasizing the need for models simulating real life complexity.We review a novel approach to study gene environment interaction in which a brief post-natal interference with the expression of multiple genes,by hindering the activity of the ubiquitous transcription factor specificity protein 1(Sp1) is followed by later-in-life exposure of rats to stress.Finally,this review discusses the role of peripheral processes in behavioral responses,with the Sp1 model as one example demonstrating how specific behavioral patterns are linked to modulations in both peripheral and central physiological processes.We suggest that models,which take into account the tripartite reciprocal interaction between the central nervous system,peripheral systems and environmental stimuli will advance our understanding of the complexity of behavior.

Nimbolide inhibits tumor growth by restoring hepatic tight junction protein expression and reduced inflammation in an experimental hepatocarcinogenesis

BACKGROUND Altered tight junction(TJ)proteins are correlated with carcinogenesis and tumor development.Nimbolide is a tetranotriterpenoid that has been shown to have antioxidant and anti-proliferative properties;however,its anticancer effects and molecular mechanism in hepatocellular carcinoma(HCC)remains obscure.AIM To investigate the effect of nimbolide on TJ proteins,cell cycle progression,and hepatic inflammation in a mouse model of HCC.METHODS HCC was induced in male Swiss albino mice(CD-1 strain)by a single intraperitoneal injection of 100 mg/kg diethylnitrosamine(DEN)followed by 80 ppm N-nitrosomorpholine(NMOR)in drinking water for 28 wk.After 28 wk,nimbolide(6 mg/kg)was given orally for four consecutive weeks in DEN/NMOR induced HCC mice.At the end of the 32nd week,all the mice were sacrificed and blood and liver samples were collected for various analyses.Macroscopic examinations of hepatic nodules were assessed.Liver histology and HCC tumor markers such as alpha-fetoprotein(AFP)and glypican-3 were measured.Expression of TJ proteins,cell proliferation,and cell cycle markers,inflammatory markers,and oxidative stress markers were analyzed.In silico analysis was performed to confirm the binding and modulatory effect of nimbolide on zonula occludens 1(ZO-1),nuclear factor of kappa light polypeptide gene enhancer in B-cells(NF-κB),and tumor necrosis factor alpha(TNF-α).RESULTS We found nimbolide treatment at a concentration of 6 mg/kg to HCC mice reduced hepatic tumor size by 52.08%and tumor volume(P<0.01),and delayed tumor growth in HCC mice with a concomitant reduction in tumor markers such as AFP levels(P<0.01)and glypican-3 expression(P<0.05).Furthermore,nimbolide treatment increased tight junction proteins such as ZO-1 and occludin expression(P<0.05,respectively)and reduced ZO-1 associated nucleic acid binding protein expression(P<0.001)in HCC mice liver.Nimbolide treatment to HCC mice also inhibited cell proliferation and suppressed cell cycle progression by attenuating proliferating cell nuclear antigen(P<0.01),cyclin dependent kinase(P<0.05),and CyclinD1(P<0.05)expression.In addition,nimbolide treatment to HCC mice ameliorated hepatic inflammation by reducing NF-κB,interleukin 1 beta and TNF-αexpression(P<0.05,respectively)and abrogated oxidative stress by attenuating 4-hydroxynonenal expression(P<0.01).Molecular docking studies further confirmed that nimbolide interacts with ZO-1,NF-κB,and TNF-α.CONCLUSION Our current study showed for the first time that nimbolide exhibits anticancer effect by reducing tumor size,tumor burden and by suppressing cell cycle progression in HCC mice.Furthermore,nimbolide treatment to HCC mice ameliorated inflammation and oxidative stress,and improved TJ proteins expression.Consequently,nimbolide could be potentially used as a natural therapeutic agent for HCC treatment,however further human studies are warranted.

Ultrasensitive detection of DNA and protein markers in cancer cells

Cancer cells differ from normal cells in various parameters, and these differences are caused by genomic mutations and consequential altered gene expression. The genetic and functional heterogeneity of tumor cells is a major challenge in cancer research, detection, and effective treatment. As such, the use of diagnostic methods is important to reveal this heterogeneity at the single-cell level. Droplet microfluidic devices are effective tools that provide exceptional sensitivity for analyzing single cells and molecules. In this review, we highlight two novel methods that employ droplet microfluidics for ultrasensitive detection of nucleic acids and protein markers in cancer cells. We also discuss the future practical applications of these methods.

Fasciculation and elongation zeta proteins 1 and 2: From structural flexibility to functional diversity

Fasciculation and elongation zeta/zygin(FEZ) proteins are a family of hub proteins and share many characteristics like high connectivity in interaction networks, they are involved in several cellular processes, evolve slowly and in general have intrinsically disordered regions. In 1985, unc-76 gene was firstly described and involved in axonal growth in C. elegans, and in 1997 Bloom and Horvitz enrolled also the human homologues genes, FEZ1 and FEZ2, in this process. While nematodes possess one gene(unc-76), mammalians have one more copy(FEZ1 and FEZ2). Several animal models have been used to study FEZ family functions like: C. elegans, D. melanogaster, R. novergicus and human cells.Complementation assays were performed and demonstrated the function conservation between paralogues. Human FEZ1 protein is more studied followed by UNC-76 and FEZ2 proteins, respectively. While FEZ1 and UNC-76 shared interaction partners, FEZ2 evolved and increased the number of protein-protein interactions(PPI) with cytoplasmatic partners. FEZ proteins are implicated in intracellular transport, acting as bivalent cargo transport adaptors in kinesinmediated movement. Especially in light of this cellular function, this family of proteins has been involved in several processes like neuronal development,neurological disorders, viral infection and autophagy. However, nuclear functions of FEZ proteins have been explored as well, due to high content of PPI with nuclear proteins, correlating FEZ1 expression to Sox2 and Hoxb4 gene regulation and retinoic acid signaling. These recent findings open new avenue to study FEZ proteins functions and its involvement in already described processes.This review intends to reunite aspects of evolution, structure, interaction partners and function of FEZ proteins and correlate them to physiological and pathological processes.

Prediction of Protein-Protein Interactions by a Novel Model Based on Domain Information

Domain-based protein-protein interactions( PPIs) is a problem that has drawn the attentions of many researchers in recent years and it has been studied using lots of computational approaches from many different perspectives. Existing domain-based methods to predict PPIs typically infer domain interactions from known interacting sets of proteins. However,these methods are costly and complex to implement. In this paper, a simple and effective prediction model is proposed. In this model,an improved multiinstance learning( MIL) algorithm( MilCaA) is designed that doesn't need to take the domain interactions into consideration to construct MIL bags. Then, the pseudo-amino acid composition( PseAAC) transformation method is used to encode the instances in a multi-instance bag and the principal components analysis( PCA) is also used to reduce the feature dimension. Finally, several traditional machine learning and MIL methods are used to verify the proposed model. Experimental results demonstrate that MilCaA performs better than state-of-the-art techniques including the traditional machine learning methods which are widely used in PPIs prediction.

Thermodynamics of the long range assembly of safranine T on molecular surfaces of nucleic acids

By making use of the fluorescence quenching properties of safranine T(ST) in its long range assembly on the molecular surfaces of nucleic acids, the assembly number and constant of ST with calf thymus DNA, fish sperm DNA and yeast RNA were determined at 12℃. The corresponding free energy change, enthalpy change and entropy change of the long range assembly were calculated at the same temperature. It was found the assembly complexes are very stable and the assembly is a spontaneous process characterized an entropy increase.

抑制LncRNA PANDA表达对人心脏瓣膜间质细胞钙化的改善作用及其机制

目的观察抑制长链非编码RNA PANDA(LncRNA PANDA)表达对人心脏瓣膜间质细胞(hVICs)钙化的影响,并探讨其机制是否与核酸转录因子YA(NF-YA)、凋亡相关蛋白Bax、锚定蛋白2(Notch2)、骨形态发生蛋白2(BMP-2)有关。方法将体外培养的hVICs分为三组,正常对照组加入间质细胞培养基+10%胎牛血清,培养7 d;钙化组加入钙化诱导液,培养7 d。PANDA-siRNA组加入钙化诱导液培养3 d后,采用Lipofectamine^(TM)3000转染试剂盒转染PANDA-siRNA,再培养4 d。取各组分组培养7 d的细胞,采用实时荧光定量PCR法检测LncRNA PANDA相对表达量,光学显微镜观察细胞形态,Western blotting法检测NF-YA、Bax、Notch2、BMP-2蛋白相对表达量,ELISA法检测细胞上清液BMP-2水平。结果PANDA-siRNA组、正常对照组、钙化组细胞LncRNA PANDA相对表达量及上清液BMP-2蛋白水平均依次升高,组间两两比较P均<0.05。PANDA-siRNA组细胞结构清晰,呈条索状生长,生长稍缓慢;钙化组细胞成骨样改变,细胞聚集,呈网状结构;正常对照组细胞贴壁生长,生长迅速。与正常对照组比较,钙化组细胞NF-YA、Bax、Notch2、BMP-2蛋白相对表达量均升高,PANDA-siRNA组均降低(P均<0.05)。结论诱导钙化后的hVICs LncRNA PANDA表达升高,抑制LncRNA PANDA表达可减轻其成骨样改变,其机制可能与降低NF-YA、Bax、Notch2、BMP-2表达有关。

脂肪酸结合蛋白5结合Vimentin蛋白在肝癌中的作用机制

目的 筛选和验证与脂肪酸结合蛋白5(FABP5)结合的互作蛋白,同时研究FABP5与候选蛋白的调控关系,进一步探讨FABP5在肝癌中的作用机制。方法 采用免疫沉淀联合串联质谱分析方法(IP-MS)筛选出与FABP5相互结合的蛋白;通过免疫共沉淀实验(Co-IP)从外源性和内源性层面验证FABP5与候选互作蛋白的结合关系;利用RT-qPCR、Western blot和免疫荧光法观察敲低FABP5对肝癌细胞中波形蛋白(Vimentin)转录和翻译水平的影响;通过鬼笔环肽染色实验观察过表达FABP5对肝癌细胞骨架的影响。结果 IP-MS鉴定出336个与FABP5相互结合的潜在靶蛋白,结合文献,挑选出5个与肿瘤相关的候选蛋白,分别为PRDX1、PRSS3、PKM、HSP90AA1和Vimentin蛋白。通过外源性和内源性Co-IP实验证实FABP5与Vimentin蛋白存在结合关系。敲低FABP5对肝癌细胞中Vimentin mRNA的表达没有显著作用,但可抑制Vimentin蛋白的表达,而过表达FABP5会影响肝癌细胞的骨架。结论 FABP5促进肝癌细胞的迁移和侵袭,其机制可能与FABP5结合调控Vimentin蛋白和影响细胞骨架重塑有关,有望成为抗肝癌的潜在靶点,为肝癌的治疗提供新的思路。

酚酸与蛋白质和碳水化合物相互作用及对面包面团的影响研究进展

近年来,研究人员常利用食品各组分之间的相互作用调节其感官性状和功能特性。酚酸、蛋白质和碳水化合物三者在面食制品中广泛存在并发挥着重要作用。目前为止,研究主要集中在酚酸-蛋白质和酚酸-碳水化合物的相互作用,以及二者相互作用在食品加工、机体保健等方面的应用。酚酸、蛋白质、碳水化合物所构成的三元体系中伴随着复杂的相互作用,这些相互作用能够赋予面食制品不同的感官性状和功能特性。本文主要介绍了酚酸、蛋白质和碳水化合物三者间的相互作用及其影响面包面团感官特性和功能特性等的研究进展,以期为酚酸、蛋白质和碳水化合物组成的三元体系在面食制品中的应用提供理论指导。

微波条件下大豆蛋白-绿原酸复合物的理化及结构特性

为探究微波条件下绿原酸对大豆蛋白理化性质和结构特性的影响,采用微波处理大豆蛋白-绿原酸复合物,分析其溶解度、持水性、乳化性、持油性和起泡性的变化,进而对其晶体结构进行表征并观察颗粒形态。结果表明:添加绿原酸使大豆蛋白的溶解度、持油性、起泡性降低,分别为290.55μg/mL,269.70%,143.67%,而泡沫稳定性和乳化性升高,分别为21.67%和43.00%;在功率700 W下微波处理5 min,可使大豆蛋白-绿原酸复合物的溶解度、持油性、泡沫稳定性和乳化性升高,分别达到368.00μg/mL,402.51%,156.30%和52.67%,而持水性降低至432.88%。大豆蛋白-绿原酸复合物结构分析结果显示,衍射峰强度和结晶度下降,并出现新的衍射峰,粒径明显减小,表面粗糙,凹凸不平,结构向内部卷曲,且受微波作用影响明显。结论:微波处理可在一定程度上抵消因多酚加入而引起的蛋白质溶解性和持油性的降低,微波条件下加入绿原酸能有效改善大豆蛋白的起泡性和乳化性能。

基于IP联合蛋白质组学探讨ENG互作蛋白在bEnd.3细胞中的作用

目的本研究拟筛选并验证在脑微血管内皮细胞(bEnd.3)中Endoglin(ENG)的互作蛋白及其作用。方法采用蛋白质组学和生物信息学技术鉴定并富集ENG互作蛋白,对这些互作蛋白进行亚细胞定位、GO功能注释、IPR注释和蛋白互作网络等分析。将以上分析筛选出的ENG互作蛋白,采用免疫共沉淀(IP)实验、细胞免疫荧光(IF)和蛋白免疫印迹(WB)技术进行验证和对比,探究ENG互作蛋白在棕榈酸(PA)、基因沉默和过表达ENG处理bEnd.3细胞中的表达变化及作用。结果通过蛋白质组学分析,bEnd.3细胞中ENG互作蛋白在亚细胞定位分析中细胞骨架相关成分呈现出较高的占比;通过GO注释和IPR注释进一步发现,是细胞骨架中的中间纤维和微丝蛋白呈现较高的富集状态。ENG与细胞骨架蛋白互作热力图结果显示,与对照组相比,PA处理的bEnd.3细胞中微丝蛋白Filamin B(Flnb)数值显著降低。IP和IF结果显示,bEnd.3细胞中ENG与Flnb存在蛋白互作和共定位情况。WB结果显示,bEnd.3细胞在PA处理条件下,ENG和Flnb蛋白表达均下降;在ENG沉默条件下,Flnb蛋白随ENG表达的减少而降低;在ENG过表达条件下,Flnb蛋白随ENG表达的增加而升高。结论ENG互作蛋白广泛参与到多种相关的生物途径以及信号通路之中,ENG在bEnd.3细胞中与Flnb蛋白存在相互作用且二者具有共定位现象,ENG还能够调控PA处理的bEnd.3细胞Flnb蛋白表达水平。

基于多光谱技术分析绿原酸与肌原纤维蛋白相互作用的初步研究

本研究以高白鲑肌原纤维蛋白(Myofibrillar Protein,MP)为研究对象,探究不同浓度(6、30、150、300μmol/g)绿原酸(Chlorogenic Acid,CA)与MP相互作用的结构变化及结合性质。在25℃下孵育形成不同CA-MP复合物,通过测定复合物的理化性质(总巯基,表面疏水性),二级,三级结构变化(傅里叶红外光谱、同步荧光、三维荧光),结合性质(紫外光谱,荧光猝灭及热力学参数)分析CA-MP复合物相互作用情况。结果表明,在300μmol/g CA存在下,蛋白总巯基含量和表面疏水性分别骤降25.65%,40.26%(P<0.05);蛋白质二级结构随之展开,α-螺旋含量下降至11.73%,造成蛋白结构稳定性降低;同步荧光与三维荧光光谱表明CA对蛋白荧光具有猝灭作用,且色氨酸比酪氨酸的猝灭效果高7.90%。紫外光谱和荧光猝灭证实CA-MP形成复合物且二者的结合为静态猝灭,热力学参数进一步验证二者相互作用的主导力为疏水作用力。本研究旨在为多酚与高白鲑MP相互作用提供有价值的信息,为后续对不同结构多酚与高白鲑肌球蛋白的相互作用机制提供研究基础。

Amino acids essential for the interaction between cellular heat shock protein 90 and a Kaposi's sarcoma-associated herpesvirus-encoded protein kinase ORF36

Dear Editor,Protein-protein interactions（PPIs）often play important roles in biological processes（Zhang et al.,2016）.The split Renilla luciferase complementation assay（SRLCA）is one of the methods in studying PPIs.SRLCA is based on the complementation of the N-terminal domains of Renilla luciferase（LN）and C-terminal domains of Renilla luciferase （LC） non-functional halves of Renilla luciferase fused to possibly interacting proteins and emit luminescence （Deng et al., 2011; Jiang et al., 2010） （Supplementary Figure S1A）.

CRISPR/Cas12a技术在动物疫病检测方面的应用

CRISPR/Cas系统是由簇状规则间隔的短回文重复序列(CRISPR)和CRISPR相关蛋白(Cas)组成的一种基因编辑技术,可以特异地切割和识别靶标核酸基因。该技术具有检测速度快、灵敏度高和特异性强的优势,因此被广泛应用于动物疫病检测领域。本文就CRISPR/Cas12a结合等温核酸扩增技术和可视化技术在动物疫病检测中的应用进行综述,并对其应用前景进行展望,以期为我国的养殖业和进境动物疫病的监测提供技术支撑。

植物酚酸与面筋蛋白相互作用及其对面团品质的影响研究进展

针对近年来有关植物酚酸与面筋蛋白相互作用研究取得的进展,特别是对不同结构的植物酚酸与面筋蛋白的相互作用机制、影响因素以及相互作用对面团品质的影响进行了综述,以期为面制品的发展提供参考。