Proanthocyanidins prevent tau protein aggregation and disintegrate tau filaments

Occurrence of neurofibrillary tangles of the tau protein is a hallmark of tau-related neurodegenerative diseases, i.e. Alzheimer's disease(AD) and frontotemporal dementia. The pathological mechanism underlying AD remains poorly understood, and effective treatments are still unavailable to mitigate the disease.Inhibiting of tau aggregation and disrupting the existing fibrils are key targets in drug discovery towards preventing or curing AD. In this study, grape seed proanthocyanidins(GSPs) was found to effectively inhibit the repeat domain of tau(tau-RD) aggregation and disaggregate tau-RD fibrils in a concentrationdependent manner by inhibiting β-sheet formation of tau-RD. In cells, GSPs relieved cytotoxicity induced by tau-RD aggregates. Molecular dynamics simulations indicated that strong hydrogen bonding,hydrophobic interaction and π-π stacking between GSPs and tau-RD protein were major reasons why GSPs had high inhibitory activity on tau-RD fibrillogenesis. These results provide preliminary data to develop GSPs into medicines, foodstuffs or nutritional supplements for AD patients, suggesting that GSPs could be a candidate molecule in the drug design for AD therapeutics.

Natural polyphenols effects on protein aggregates in Alzheimer＇s and Parkinson＇s prion-like diseases

Alzheimer＇s and Parkinson＇s diseases are the most common neurodegenerative diseases. They are characterized by protein aggregates and so can be considered as prion-like disease. The major components of these deposits are amyloid peptide and tau for Alzheimer＇s disease, α-synuclein and synphilin-1 for Parkinson＇s disease. Drugs currently proposed to treat these pathologies do not prevent neurodegenerative processes and are mainly symptomatic therapies. Molecules inducing inhibition of aggregation or disaggregation of these proteins could have beneficial effects, especially if they have other beneficial effects for these diseases. Thus, several natural polyphenols, which have antioxidative, anti-inflammatory and neuroprotective properties, have been largely studied, for their effects on protein aggregates found in these diseases, notably in vitro. In this article, we propose to review the significant papers concerning the role of polyphenols on aggregation and disaggregation of amyloid peptide, tau, α-synuclein, synphilin-1, suggesting that these compounds could be useful in the treatments in Alzheimer＇s and Parkinson＇s diseases.

A Rapid Electrophoresis Method on Agarose Gel to Characterise Dairy Protein Aggregates

Heat treatment of milk may cause whey proteins and caseins to form aggregates. These soluble and micellar aggregates and their other properties (size, composition, shape, etc.) can affect the techno-functionalities to the milk, conferring interesting or negative features depending on the application in dairy industries. In this study, we propose a new approach to characterise those protein aggregates. SDS-agarose electrophoresis is followed by the calculation of a retention factor (Rf) for each protein spot. Rf allows milk aggregates to be compared qualitatively under the same conditions. This method could be transposed to the dairy industry for a better knowledge of the milk subsequent to heat treatment.

RNA binding protein BOULE forms aggregates in mammalian testis

Amyloids have traditionally been considered pathologic protein aggregates which contribute to neurodegeneration.New evidence however increasingly suggests that non-pathological amyloids are formed in animals during normal development.Amyloid-like aggregate formation was originally thought to be a conserved feature of animal gametogenesis.This hypothesis was based on findings which suggest that regulated amyloid formations govern yeast meiosis by way of meiosis-specific RNA binding proteins.Additional support came from studies which demonstrate that DAZL,a mammalian gametogenesis-specific RNA binding protein,also forms SDS-resistant aggregates in vivo.Here,we report evidence of aggregated BOULE formations,another DAZ family protein,during sperm development.Data suggest that in mouse testis,BOULE forms SDS-resistant amyloid-like aggregates.BOULE aggregate formation correlates with dynamic developmental expression during spermatogenesis but disappeared in Boule knockout testis.We also mapped essential small region in vitro BOULE aggregations,immediately downstream DAZ repeats,and found that aggregations positively correlated with temperature.We also performed enhanced UV cross-linking immunoprecipitation on BOULE aggregates from mouse testes and found that aggregates bind with a large number of spermatogenesis-related mRNAs.These findings provide insight into the amyloidogenic properties of gametogenesis-specific RNA binding proteins as a conserved feature in mammalian reproduction.Further investigation is warranted to understand the functional significance of BOULE amyloid-like formation during mouse spermatogenesis.

<i>Saccharomyces cerevisiae</i>as a Model to Confirm the Ability of FTIR to Evaluate the Presence of Protein Aggregates

It is known that the presence of protein aggregates in biological samples is associated with natural aging processes and age-related diseases. The objective of this technical study was to evaluate the potential of Fourier Transform Infrared Spectroscopy to identify the presence of protein aggregates in Saccharomyces cerevisiae containing high levels of protein aggregates. We acquired ATR-FTIR spectra at mid-infrared range (between 4000 and 600 cm-1) and used multivariate analysis to analyze the data. Significant differences between spectra of wild type and mutant strains in the spectral range assigned to proteins were observed. In particular, an increase in β-sheet structures in mutant strains (spectral signals at 1683 and 1628 cm-1) was observed, indicating the putative presence of protein aggregates. These results prove the capacity of FTIR to evaluate changes in protein conformation, mainly protein aggregation, in a fast, simple and non-expensive way, producing insights on the possible application of this technique to the detection of protein aggregates in human biological samples.

Solution pH jump during antibody and Fc-fusion protein thaw leads to increased aggregation

Freeze-thaw cycles impact the amount of aggregation observed in antibodies and Fc-fusion proteins. Various formulation strategies are used to mitigate the amount of aggregation that occurs upon putting a protein solution through a freeze-thaw cycle. Additionally, low pH solutions cause native antibodies to unfold, which are prone to aggregate upon pH neutralization, There is great interest in the mechanism that causes therapeutic proteins to aggregate since aggregate species can cause unwanted immunogenicity in patients, Herein, an increase in aggregation is reported when the pH is adjusted from pH 3 up to a pH ranging from pH 4 to pH 7 during the thaw process of a frozen antibody solution, Raising the pH during the thaw process caused a significant increase in the percent aggregation observed. Two antibodies and one Fc-fusion protein were evaluated during the pH jump thaw process and similar effects were observed. The results provide a new tool to study the kinetics of therapeutic protein ag- gregation upon pH increase,

Multiple effects of polydopamine nanoparticles on Cu^(2+)-mediated Alzheimer's β-amyloid aggregation

Deposition of β-amyloid protein(Aβ) is the main hallmark of Alzheimer's disease(AD), and it has been well recognized that Cu^(2+)-mediated Aβ aggregation plays a crucial role in AD pathological processes.Cu^(2+)binding to Aβ can promote the production of reactive oxygen species(ROS) through Fenton-like reactions and produce more toxic Aβ-Cu^(2+)species under Cu^(2+)stimulation. Thus, the development of nanomaterials that can inhibit Cu^(2+)-mediated Aβ aggregation and degrade Aβ-Cu^(2+)complexes is considered an effective strategy for the prevention and treatment of AD. In this study, polydopamine nanoparticles(PDA NPs) were prepared and the results reveal that PDA NPs potently inhibit Cu^(2+)-mediated Aβaggregation and effectively reduce the formation of Aβ-Cu^(2+)complexes. In vitro experiments show that PDA NPs efficiently eliminate ROS generation catalyzed by Cu^(2+)or Aβ-Cu^(2+)complexes, thus rescuing cultured cells by reducing intracellular ROS levels. More importantly, PDA NPs can depolymerize Aβ-Cu^(2+)complexes, and the degradation of Aβ-Cu^(2+)complexes is promoted by near-infrared light irradiation due to their high photothermal conversion ability. In vivo studies reveal that PDA NPs significantly reduce the deposition of Aβ plaques in the presence of Cu^(2+)and extend the lifespan of AD nematodes from 11 to 14 d. Thus, the PDA NPs developed herein are multifunctional against Cu^(2+)-mediated Aβ aggregation for the potential prevention and treatment of AD.

Pyropia haitanensis polysaccharide extends lifespan by inhibiting protein aggregation in Caenorhabditis elegans

Pyropia haitanensis polysaccharide(LP)have been found for having many excellent functions such as anti-aging.Using Caenorhabditis elegans models,we evaluated the anti-aging activity of LP by observing the lifespan,reproduction,pharyngeal pumping,stress response,quantitative fluorescence of polyglutamic acid,and nuclear localization of DAF-16 of worms.The results reveal that LP could extend the adult lifespan of wild-type and polyQ nematodes,indicating a connection of its anti-aging benefit with the toxicity-suppressing effect.The number of polyglutamic acid aggregates in high concentration groups decreased by 24.39%(P<0.05)to the control.The high-dose group strongly induced DAF-16 nuclear translocation over intermediate and cytosolic localizations compared with the control(P<0.001).Therefore,we believe that LP could extend the lifespan and reduce the protein aggregation in C.elegans through nuclear DAF-16∷GFP expression.

Recombinant Human REG I<i>α</i>Aggregates <i>Staphylococcus aureus</i>—Exhibits a Lectin-Like Function

Staphylococcus aureus is pathogenic to humans with worldwide health care concern due to its ability to evade the immune system and develop resistance to multiple drugs. Reg family proteins are C-type lectins with antimicrobial properties. Bacterial aggregation through binding to microbial cell surface sugar and/or lipid moieties is key mechanism employed in the process. In the present study we have analysed the antimicrobial effect of human REG Iα on S. aureus. Aggregation of mid-log phase culture of S. aureus was observed in presence of purified recombinant REG Iα. Therefore REG Iα can be applied in eliminating S. aureus infections in humans.

Forward-Light-Scattering Characterization of Pre-Crystalline Aggregates in Crystallizing Lysozyme Solutions

We present a method to characterize lysozyme pre-crystalline aggregates using a forward-light-scattering technique, which is highly sensitive to protein aggregates. The static light scattering properties at small angles of crystallizing lysozyme aggregates are discussed, and related to the crystallization conditions based on the concentration of added precipitant NaCl. Lysozyme solutions that started to crystallize because of precipitant exhibited profiles of forward light scattering that could be fitted by non-integer power laws, which indicated fractal aggregations of lysozyme had formed. Pre-crystalline solutions, in which lysozyme crystals later grew, had dense structural fractal clusters with fractal dimensions of D > 1.5. In contrast, solutions with aggregates in which crystals did not grow, had forward-light-scattering profiles that deviated from a power law or had lower power values.

豆类蛋白聚集机制及调控措施研究进展

目前在食品加工、化学工业生产以及生物医药等领域普遍存在蛋白质聚集的现象。近年来,豆类蛋白生产规模不断扩大,其营养价值及经济效价优势显著。基于此,越来越多的学者对豆类蛋白聚集、解聚行为进行了深入探讨。但豆类蛋白在食品加工过程中会产生一些聚集行为,这是不可避免的现象。随着加工食品的手段越来越多样化,豆类蛋白的聚集行为对食品品质、口感、风味的影响也逐渐引起人们的重视。文章介绍了豆类蛋白聚集行为的产生机理,系统详尽地综述了调控豆类蛋白聚集行为的措施及对豆类蛋白聚集行为进行表征的方法。相信豆类蛋白在未来可以成为更好的蛋白质补充方式,有更加广泛的发展和应用空间,并希望为研究豆类蛋白聚集行为提供更多的理论支持。

碱提酸沉参数影响大豆分离蛋白变性、聚集和流变特性的研究进展

pH值、NaCl和温度是制备大豆分离蛋白的重要参数。pH值和NaCl通过改变蛋白质表面电荷和静电斥力影响其聚集程度;温度通过改变蛋白质表面疏水性和/或二硫键影响其聚集程度,三者进而改变其颗粒大小或致密程度,引起流变性和下游应用特性的变化。本文从相互作用、热稳定性、聚集程度及胶凝特性等方面综述了pH值、NaCl和温度对大豆分离蛋白及其组分glycinin和β-conglycinin的变性、聚集和流变特性的影响,探讨了可能的机理;梳理了蛋白质聚集度、凝胶链粗厚度、凝胶链曲直率、凝胶网络连续性与凝胶强度之间的关系;总结了pH值、NaCl和温度对蛋白质聚集影响的差异。旨在为通过制备参数调控大豆分离蛋白聚集程度提供帮助。

大豆分离蛋白制备过程中热处理及干燥方式对其热聚集行为和凝胶性能的影响

该研究以低温脱脂豆粕为原料,采用“碱溶酸沉”法收集大豆蛋白沉淀,对其进行分散、热处理和喷雾干燥或冷冻干燥制备获得大豆分离蛋白(SPI)。通过观察该产品的热聚集行为及其所成热致凝胶机械性能,考察热处理和干燥方式对所得产品凝胶性能的影响。结果表明,热处理使制得大豆分离蛋白多以聚集体的形式存在,导致其溶解性(pH值7.0)分别从79.9%和69.8%下降至35.2%和42.0%。相对于经过热处理制得的大豆分离蛋白,未经过热处理制得的大豆分离蛋白其差示扫描量热仪分析图存在78℃和98℃吸热峰;其分散液再次经历热处理后,分散液中蛋白的体积分数约从30%下降至20%,展现出进一步聚集并形成有序结构的趋势;对于质量分数为16%的喷雾干燥大豆分离蛋白(SD-SPI)和冷冻干燥大豆分离蛋白(FD-SPI)样品分散液所制备的凝胶,其断裂应力分别为10.80 kPa和12.50 kPa,显著高于对应HSD-SPI(经热处理)凝胶的3.69 kPa和HFD-SPI(经热处理)的4.36 kPa,但后两者硬度高于前两者。另一方面,干燥方式没有对所得大豆分离蛋白的凝胶性质产生显著的影响。可见,大豆分离蛋白制备过程中对大豆蛋白分散液进行升温热处理是影响所得蛋白产品溶解性、聚集行为和凝胶性能的关键步骤。寻找相应的替代工艺有望提高大豆分离蛋白的品质和功能特性,拓展其在食品工业尤其是植物基食品中的应用。

传统广式烤鸭烫皮工艺中蛋白质变性与品质关系分析

以樱桃谷鸭为原料,研究了烫皮过程温度变化和烫皮前后的水分、色泽、蛋白变性、显微结构等变化规律。结果表明:90~95℃,5 s的烫皮程度已达到传统烫皮感官要求,鸭皮表面温度到达80℃以上,皮内温度达到45℃以上;晾皮失水速度差异不显著(P>0.05),与鸭皮中的蛋白质变性程度测定(DSC)实验结果一致,显示该温度下蛋白发生变性、聚集。进一步探究90℃烫皮条件,结果表明,90℃烫皮7 s(90℃-7 s)晾皮3 h(含水量22.01%)比90℃烫皮9 s(90℃-9 s)晾皮4 h(含水量20.52%)膨化效果更好;DSC数据也显示90℃-7 s蛋白质热聚集程度大于烫皮5 s(P<0.05),90℃-9 s的样品蛋白质存在凝胶结构。综上所述,传统广式烤鸭鸭皮脆化与膨化的核心是控制烫皮后鸭皮中蛋白质处于变性聚集的状态及此状态下皮的水分含量,研究结果为探究传统广式烤鸭烫皮机理并为其烫皮工艺改良提供理论支持和技术参考。

不同筋力小麦面筋聚集特性及结构特性分析

通过分析面团质构特性、面筋蛋白聚集特性、面筋蛋白含量、分子量分布、二级结构以及微观结构,研究“郑麦103”、“郑麦136”、“新麦26”3种不同筋力小麦面筋蛋白聚集特性及结构特性并探讨其差异。结果表明:随着小麦筋力的增强,面团的硬度、弹性、内聚性、胶着性、咀嚼性和回复性升高,黏性降低。相比于“郑麦103”和“郑麦136”,“新麦26”的峰值形成时间较长、峰值扭矩较大且面筋蛋白聚集能较高,面筋蛋白含量更高。随着小麦筋力的增强,面筋蛋白各亚基含量及种类增多。与“郑麦103”和“郑麦136”相比,“新麦26”面筋蛋白的二级结构中β-折叠和β-转角含量增多,α-螺旋含量降低,无规则卷曲含量先减少再增加。小麦筋力越强,面筋蛋白网络结构连续性越好,包裹淀粉能力越强。综上所述,相比于“郑麦103”和“郑麦136”,“新麦26”面筋蛋白含量较高,面筋蛋白亚基种类较多,可促进面筋蛋白的聚集,面筋蛋白中增多的β-折叠结构促进面筋蛋白结构的稳定性,面筋网络结构的连续性增强,进而提高面团的强度和弹性。

肌萎缩侧索硬化症发病机制及药物研究进展

肌萎缩侧索硬化症(amyotrophic lateral sclerosis,ALS)是一种病因未明的运动神经元疾病,同时累及上、下运动神经元,患者表现出进行性加重的肌肉萎缩、无力、瘫痪,最终死于呼吸衰竭。ALS具有进展快、致死率高的特点,该疾病异质性强,发病机制研究不明确,缺乏有效的治疗药物。因此,探究ALS疾病病理机制、助力新药研发,解决未被满足的临床需求具有重大的科学价值及社会意义。该文针对ALS的发病机制及治疗药物的研究现状进行综述,希望为ALS药物研发提供思路。

各国对注射液不溶性微粒的监管要求及在生物技术药物的应用思考

目的:通过对比《中华人民共和国药典》2020年版(ChP 2020)、2023年美国药典(USP-NF2023)、欧洲药典11.0版(EP 11.0)、日本药典18版(JP 18)中注射剂不溶性微粒检测方法相关内容,分析不同药典对不溶性微粒的监管要求,供业界参考。以治疗性蛋白注射液为代表,结合目前各监管机构对注射液中不溶性微粒的要求,指出现有要求未能对此类生物技术药物中具有免疫原性潜力的小粒径(0.1~10μm)蛋白聚集体微粒进行控制,并从三方面提出建议以加强此类药物的质量控制,更好地保障患者的用药安全。方法:通过对比ChP 2020、USP-NF 2023、EP 11.0、JP 18中注射剂不溶性微粒检测的章节内容,对检测方法、限定标准和系统适用性检测等内容进行分析总结。通过收集归纳中、美、日、欧关于生物技术药物中不溶性微粒的药典要求和相关技术指导原则,明确目前不同机构对于生物技术药物中不溶性微粒的监管要求。结果与结论:(1)对于注射液中不溶性微粒检查方法,不同药典收载的方法均为光阻法和显微计数法,但是对各方法的适用条件的限定不同。此外,USP-NF 2023、EP 11.0和JP 18中提出的检测方法一致,Chp 2020主要在25 mL以下规格的供试品检测方面与其他三部药典有较大差异;在系统适用性检测方面,USP-NF 2023更为全面,Chp 2020在此方面要求较少;在微粒计数和限定标准方面,各药典一致;(2)对于生物技术药物,除Chp 2020外,其他药典均收载了生物技术药物不溶性微粒的检测方法,但是并未对0.1~10μm小粒径微粒进行计数和控制,仍然无法控制小粒径蛋白聚集体可能带来的免疫原性的危害;也未见各机构明确对生物技术药物中有免疫原风险的小粒径不溶性微粒的监管要求和标准。为此笔者分别在方法学研究方面、数据收集方面、研发技术要求方面提出三点建议,以更好地保障患者的用药安全。

Fluorogenic sensing of amorphous aggregates,amyloid fibers,and chaperone activity via a near-infrared aggregation-induced emission-active probe

The presence of protein aggregates in numerous human diseases underscores the significance of detecting these aggregates to comprehend disease mechanisms and develop novel therapeutic approaches for combating these disorders.Despite the development of various biosensors and fluorescent probes that selectively target amyloid fibers or amorphous aggregates,there is still a lack of tools capable of simultaneously detecting both types of aggregates.Herein,we demonstrate the quantitative discernment of amorphous aggregates by QM-FN-SO3,an aggregationinduced emission(AIE)probe initially designed for detecting amyloid fibers.This probe easily penetrates the membranes of the widely-used prokaryotic model organism Escherichia coli,enabling the visualization of both amorphous aggregates and amyloid fibers through near-infrared fluorescence.Notably,the probe exhibits sensitivity in distinguishing the varying aggregation propensities of proteins,regardless of whether they form amorphous aggregates or amyloid fibers in vivo.These properties contribute to the successful application of the QM-FN-SO3 probe in the subsequent investigation of the antiaggregation activities of two outer membrane protein(OMP)chaperones,both in vitro and in their physiological environment.Overall,our work introduces a near-infrared fluorescent chemical probe that can quantitatively detect amyloid fibers and amorphous aggregates with high sensitivity in vitro and in vivo.Furthermore,it demonstrates the applicability of the probe in chaperone biology and its potential as a high-throughput screening tool for protein aggregation inhibitors and folding factors.

维生素K治疗神经退行性疾病的分子机制与临床研究进展

目的 总结维生素K治疗神经退行性疾病的分子机制与临床研究进展。方法 采用文献分析法,检索PubMed和中国知网数据库中自建库起至2024年2月有关维生素K治疗神经退行性疾病的文献,以蛋白质错误折叠、线粒体功能障碍、氧化应激、神经炎症和铁死亡为切入点,梳理维生素K治疗神经退行性疾病的分子机制。结果与结论 维生素K通过影响蛋白聚集及自噬的调控,可改善线粒体功能,减少氧化应激、神经炎症、铁死亡等的发生,逆转细胞或动物模型的神经退行性疾病病理过程。

复合蛋白酶交联酶聚集体制备枸杞蛋白多肽

该研究利用交联酶聚体技术制备出复合蛋白酶交联酶聚体固定化酶,以酶活回收率为指标,通过单因素实验得到复合蛋白酶交联酶聚集体最佳制备条件:风味蛋白酶与木瓜蛋白酶比例为3∶1,沉淀剂硫酸铵浓度为60%,戊二醛浓度0.5%,交联时间为50分钟,交联pH为7.5。此时最大酶活回收率为80.32%。相比单一蛋白酶,复合蛋白酶交联酶聚集体具有更好的热稳定性和pH稳定性,同时表现出良好的连续多次水解枸杞蛋白的性能。以蛋白水解度为指标,优化后复合蛋白酶交联酶聚集体最佳水解条件为:温度为60℃,pH为6,酶浓度为10 mg/mL,水解时间为100 min,在此条件下枸杞蛋白水解度为41.21%,比游离复合蛋白酶提高了6.9%。