人尿液N-糖蛋白/N-糖肽规模化富集鉴定

蛋白质的N-糖基化是真核细胞中一种重要的翻译后修饰,N-糖基化修饰在调控细胞黏附、迁移、信号转导及细胞凋亡等方面扮演着关键角色.蛋白质糖基化修饰的异常变化与多种重要疾病的发生相关.尿液具有蛋白质组复杂程度低和非入侵性等特点,适合大量及连续多时间点采样研究.但由于个体差异和生理条件的影响,尿蛋白丰度的生理波动较大.目前缺...     

基于质谱技术的贝伐珠单抗及其 糖基化修饰的表征、定量与药代动力学分析

利用基质辅助激光解析电离飞行时间质谱技术、SDS-聚丙烯酰胺凝胶电泳技术以及Shot-gun蛋白质组学策略对贝伐珠单克隆抗体药物及其糖基化修饰进行了全面表征,共发现17种糖型并确定了特征肽段序列.利用液相色谱-串联质谱联用技术,采用平行反应检测模式,通过测定单抗水解后产生的特征肽段,实现了对大鼠血浆样品中单抗药物含量的绝对定量分析,获得不同给药计量下的贝伐珠单抗的药物浓度-时间曲线,同时实现了对单抗糖基化修饰各糖型的相对定量分析.本实验首先建立标准工作曲线,对大鼠血浆样品中的贝伐珠单抗进行定量分析,在线性范围内,相关系数R2=0.998,定量限为66 fmol,线性关系良好.对大鼠血浆样品的测定结果表明,高、低计量给药的贝伐珠单抗药物浓度-时间曲线趋势基本一致,浓度均为直接下降,与理论趋势相符.但是大多数糖型呈现浓度先上升的现象,之后的代谢情况因糖型差异而有所不同.     

基于整体柱的糖基化蛋白质分离富集方法的研究进展

蛋白质糖基化作为一种重要的翻译后修饰,不仅可以反映机体的健康状况,还可以充当药物治疗的靶点。因此,阐明蛋白质糖基化的修饰规律对疾病的诊断和治疗具有重要意义。然而,生物样品中糖基化蛋白质相对丰度低,复杂程度高,动态范围宽,适宜的样品前处理步骤必不可少。近年来,整体柱因具备分离快速、灵敏、高效、生物兼容性好等优点,在糖基化蛋白质分离富集领域得到了广泛关注。本文对近年来基于整体柱的糖基化蛋白质分离富集方法的研究进展进行了评述,并对其未来发展趋势进行了展望。     

抗体药物偶联物

单克隆抗体(单抗)药物是发展最为迅速的一个领域,在过去25年间大约有近30个单抗药物面世,主要用于抗癌和炎症;最近一种新的抗体药物偶联物(antibody-drug conjugate,ADC)技术取得了极大的成功。ADC是通过一个特殊的化学单元将单抗和小分子药物连接起来,充分利用抗体原有的亲合性和选择性,以及小分子药物的强药效,来降低小分子药物的毒性或延长小分子化合物的半衰期。随着一些链接技术的成熟和ADC药物上市,未来ADC将成为治疗疾病的重要手段。为了成功研制出一个新的ADC,需要对单抗、小分子药物和链接进行不断优化。一些新技术的问世也将极大促进ADC的发展。     

完整糖基化肽段的富集与质谱解析新技术研究进展

蛋白质糖基化是生物体内最重要的翻译后修饰之一,在蛋白质稳定性、细胞内和细胞间信号转导、激素活化或失活和免疫调节等生理过程和病理进程中发挥重要作用.而异常的蛋白质糖基化往往和多种疾病的发生发展密切相关,目前应用于临床检测的多种肿瘤生物标志物大多属于糖蛋白或者糖抗原.因此在组学层次系统分析蛋白质糖基化的变化对阐明生物体内糖...     

化学生物学解析疾病中O-GlcNAc糖基化功能:研究工具与策略

O-连接β-N-乙酰葡糖胺(O-GlcNAc)糖基化是广泛存在于蛋白质丝/苏氨酸残基的翻译后修饰.这一动态、可逆单糖修饰以位点特异性方式影响底物蛋白的结构和生物学功能,参与调控几乎所有细胞生理过程和重大疾病的演进过程.随着研究深入,O-GlcNAc糖基化生物功能的系统解析需要更多特异、精准的研究工具和糖蛋白质组学研究策略.近年来,化学生物学领域开发了包括小分子糖探针、生物正交糖代谢标记物、化学酶法、特异性抗体和凝集素等多种O-GlcNAc糖基化分析工具和方法,以此为基础进一步发展了O-GlcNAc糖蛋白质组学研究策略.同时,借助高分辨质谱,大量蛋白质O-GlcNAc修饰位点得以鉴定,极大促进了位点特异性O-GlcNAc的生物功能研究.本文综述了近年来这一领域的研究进展,以期为更多化学工具的开发提供依据,为揭示O-GlcNAc糖基化在疾病演进中的功能提供新的研究思路和策略.     

基于三甲基苯磺酰羟胺消除反应的氧连接氮乙酰葡萄糖胺修饰肽段的精准鉴定

氧连接氮乙酰葡萄糖胺(O-GlcNAc)是一种重要的蛋白质翻译后修饰,它在维持机体正常的生命活动中发挥着重要作用.许多研究证实,O-GlcNAc糖基化修饰稳态的破坏与人类多种疾病的发生相关,大规模富集鉴定O-GlcNAc糖基化修饰蛋白有助于发现新的临床疾病诊断标志物.由于O-GlcNAc糖基化修饰丰度较低,形成的糖苷键...     

O-GlcNAcase抑制剂

O-连接的N-乙酰葡糖胺糖基化修饰 (O-GlcNAcylation) 是一种存在于蛋白质Ser/Thr上的翻译后修饰。与磷酸化相似,它参与细胞内的信号传递,并与神经退行性疾病、Ⅱ型糖尿病、癌症等许多疾病的发病机理密切相关。O-连接的N-乙酰葡糖胺水解酶 (O-GlcNAcase, OGA) 是生物体内唯一水解蛋白质O-GlcNAc修饰的糖苷酶。因此,研究高效、专一的OGA小分子抑制剂是调节细胞中蛋白质O-GlcNAc水平的有效策略,利于阿尔茨海默病等相关神经退行性疾病新型药物的开发。结合本实验室对OGA抑制剂的研究,本文介绍了OGA的结构、催化机理及目前OGA抑制剂的研究进展,讨论了各种抑制剂的构效关系,并对OGA抑制剂的研究前景进行了展望。     

4-巯基苯硼酸修饰二维二硫化钼纳米复合材料的制备及其用于N-糖肽特异性富集

蛋白质的N-糖基化修饰在多种生物过程中发挥着至关重要的作用,近年来的许多研究证实异常的蛋白质糖基化与多种疾病的发生发展密切相关,表明糖基化蛋白质具有较大的潜力成为新的生物标志物或者药物靶标。在样本的处理过程中,对N-糖基化肽段进行富集分离后再进行质谱分析已经成为糖蛋白质组学分析前的必要步骤。但是,由于复杂生物样本中N-糖基化肽段的丰度低和离子化效率差等问题,通过质谱鉴定N-糖肽仍然是一项艰巨的任务。研究通过将纳米金线(Au)、4-巯基苯硼酸(4-MPB)与超薄二维二硫化钼(2D-MoS₂)进行反应,成功制备了一种用于富集蛋白质N-糖基化肽段的新型功能纳米复合材料(MoS₂/Au/4-MPB)。二硫化钼纳米材料的层状结构可以为反应提供大量的可修饰位点,便于修饰纳米金线;功能基团4-巯基苯基硼酸对N-糖肽具有高度的选择性,可以对生物样品中N-糖基化肽段进行特异性富集。使用标准蛋白人免疫球蛋白G(IgG)和牛血清白蛋白(BSA)胰蛋白酶酶切产物对新型功能纳米材料的N-糖基化肽段的富集性能进行评估,其灵敏度达到5 fmol,选择性达到1∶1 000。...     

氧化石墨烯固定化凝集素的制备及在糖蛋白/糖肽富集中的应用

生物体内蛋白质的糖基化修饰调控着细胞识别、细胞黏附和迁移以及免疫应答等多种生理过程,并与多种人类重大疾病的发生、发展密切相关。因此对蛋白质糖基化修饰的鉴定,不仅能够为生物学机理研究提供重要信息,对疾病诊断标志物和治疗靶标的发现也至关重要。然而在复杂生物体系中,大多数糖蛋白为低丰度蛋白质,其含量与现有质谱仪器的检测灵敏度之间存在较大差距,所以对含有不同糖型结构的糖蛋白进行全面/高效的富集,是实现高灵敏度糖蛋白鉴定的必由之路。凝集素富集作为一种有效的糖蛋白富集方法,已在糖蛋白质组学研究中得到了广泛的应用。针对现有凝集素功能化材料存在负载量偏低以及富集效率有限等问题,我们制备了两种以氧化石墨烯(GO)为载体的新型固定化凝集素,利用GO比表面积大,功能基团含量高,分散性、化学稳定性好等特点,实现了高负载量的凝集素固定(GO-ConA 2.073 mg/mg, RSD=1.0%; GO-WGA 1.908 mg/mg, RSD=0.14%)。同时考察了材料的可重复使用性与稳定性:每隔3天测一次同一GO-lectin材料对对应糖蛋白的富集效果,可以看出材料合成两周内富集效果都>200 μg/mg。将该GO-lectin成功应用于糖蛋白、糖肽的选择性富集,在糖蛋白质组学研究中体现出良好的应用潜力。     

Chemoenzymatic glycoengineering of intact IgG antibodies for gain of functions

The fine structures of Fc N-glycans can modulate the effector functions of IgG antibodies. It has been demonstrated that lack of the core fucose on the Fc N-glycans leads to drastic enhancement of antibody-dependent cellular cytotoxicity (ADCC), while terminal α2,6-sialylation of Fc glycan plays a critical role for the anti-inflammatory activity of human intravenous immunoglobulin (IVIG). We describe in this paper a highly efficient chemoenzymatic method for site-selective Fc glycoengineering of intact monoclonal antibody and IVIG. Two new glycosynthase mutants (EndoS-D233A and D233Q) were generated by site-directed mutagenesis of EndoS (an endoglycosidase from Streptococcus pyogenes ) and were found to be capable of efficiently transferring predefined N-glycans from corresponding glycan oxazolines to the Fc-deglycosylated intact IgGs without product hydrolysis. As a model study, rituximab (a therapeutic monoclonal antibody) was successfully transformed from mixtures of G0F, G1F, and G2F glycoforms to well-defined homogeneous glycoforms, including a fully sialylated (S2G2F) glycoform that may gain anti-inflammatory activity, a nonfucosylated G2 glycoform that showed significantly enhanced FcγIIIa receptor-binding activity, and an azido-tagged glycoform that can be further transformed into other glycoforms. We also found that EndoS could selectively remove the Fc N-glycans in the presence of FAB glycosylation. This finding, coupled with the remarkable transglycosylation activity of the EndoS glycosynthase mutants, permitted a highly selective glycoengineering of the IVIG's Fc glycans into a fully sialylated Fc glycoform, which may possess significantly enhanced anti-inflammatory activity. The glycoengineering approach described here provides a general platform to modulate the effector functions of IgG antibodies, enabling the optimization of therapeutic efficacy and gain of new functions of monoclonal antibodies and IVIG.     

Impact of N-Linked Glycosylation on Therapeutic Proteins

Therapeutic proteins have unique advantages over small-molecule drugs in the treatment of various diseases, such as higher target specificity, stronger pharmacological efficacy and relatively low side effects. These advantages make them increasingly valued in drug development and clinical practice. However, although highly valued, the intrinsic limitations in their physical, chemical and pharmacological properties often restrict their wider applications. As one of the most important post-translational modifications, glycosylation has been shown to exert positive effects on many properties of proteins, including molecular stability, and pharmacodynamic and pharmacokinetic characteristics. Glycoengineering, which involves changing the glycosylation patterns of proteins, is therefore expected to be an effective means of overcoming the problems of therapeutic proteins. In this review, we summarize recent efforts and advances in the glycoengineering of erythropoietin and IgG monoclonal antibodies, with the goals of illustrating the importance of this strategy in improving the performance of therapeutic proteins and providing a brief overview of how glycoengineering is applied to protein-based drugs.     

毛细管电泳技术在单克隆抗体药物分析中的应用

单克隆抗体药物在生物制药行业占有重要地位,是生物医药领域发展的主要方向。因此,单克隆抗体药物的质量控制已成为全球生物制药企业及法规机构关注的热点,对单克隆抗体药物精确表征的需求日益增加。毛细管电泳技术具有分离效率高、分析速度快、分离模式多、样品用量少等特点,已成为单克隆抗体药物分析和质量控制的重要手段。该文对毛细管凝胶电泳、毛细管等电聚焦、毛细管区带电泳等模式在单克隆抗体药物的纯度分析、等电点测定、电荷异质性分析和N-寡糖分析的应用进行综述,以期为国内单克隆抗体研究开发和生产的企事业单位提供技术参考。     

Adsorption and recovery issues of recombinant monoclonal antibodies in reversed‐phase liquid chromatography†

The poor recovery of large biomolecules is a well‐known issue in reversed‐phase liquid chromatography. Several papers have reported this problem, but the reasons behind this behavior are not yet fully understood. In the present study, state‐of‐the‐art reversed‐phase wide‐pore stationary phases were used to evaluate the adsorption of therapeutic monoclonal antibodies. These biomolecules possess molar mass of approximately 150 000 g/mol and isoelectric points between 6.6 and 9.3. Two types of stationary phases were tested, the Phenomenex Aeris Widepore (silica based), with 3.6 μm superficially porous particles, and the Waters Acquity BEH300 (ethylene‐bridged hybrid), with 1.7 μm fully porous particles. A systematic investigation was carried out using 11 immunoglobulin G1, G2, and G4 antibodies, namely, panitumumab, natalizumab, cetuximab, bevacizumab, trastuzumab, rituximab, palivizumab, belimumab, adalimumab, denosumab, and ofatumumab. All are approved by the Food and Drug Administration and the European Medicines Agency in various therapeutic indications and are considered as reference antibodies. Several test proteins, such as human serum albumin, transferrin, apoferritin, ovalbumin, and others, possessing a molar mass between 42 000 and 443 000 g/mol were also evaluated to draw reliable conclusions. The purpose of this study was to find a correlation between the adsorption of monoclonal antibodies and their physicochemical properties. Therefore, the impact of isoelectric point, molar mass, protein glycosylation, and hydrophobicity was investigated. The adsorption of intact antibodies on the stationary phase was significantly higher than that of proteins of similar size, isoelectric point, or hydrophobicity. The present study also demonstrates the unique behavior of monoclonal antibodies, contributing some unwanted and unpredictable strong secondary interactions.     

Catching protein antigens by antibody affinity electrophoresis

A new kind of affinity electrophoresis called antibody affinity electrophoresis is a technique used to capture protein antigens based on their interactions with specific monoclonal or polyclonal antibodies incorporated in the polyacrylamide gel. Polyclonal anti-glutathione-S-transferase (anti-GST), monoclonal anti-bovine serum albumin (anti-BSA), and polyclonal anti-human alpha-lactalbumin are embedded in distinct areas of a 7.5% native polyacrylamide gel. Some of the embedded antibodies get covalently and/or noncovalently incorporated into the gel matrix network. Under electrophoresis conditions, these antibodies do not show significant electrophoretic mobility, as compared to their specific protein antigen analytes. We observed that electrophoretic migration of GST, BSA, and protein G ceases when they encounter anti-GST, anti-BSA, and immunoglobulin G, respectively.     

Inverse colloidal crystal membranes for hydrophobic interaction membrane chromatography

Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography.     

十二烷基硫酸钠毛细管电泳法分析非还原单克隆抗体药物纯度的前处理条件优化

十二烷基硫酸钠毛细管电泳法因具有快速、分辨率高的优势，已成为单克隆抗体纯度分析的主流方法。在非还原单克隆抗体纯度检测中，其样品前处理过程对于结果有显著影响。为优化样品前处理，考察了以碘乙酰胺和N-乙基马来酰亚胺为巯基封闭剂，在pH 6.0~9.0的样品缓冲液条件下，不同种类和批次的单抗的纯度。发现在两种巯基封闭剂中，高pH的样品缓冲液会影响巯基封闭的效果，产生较多的抗体片段；而在低pH条件下，抗体片段较少，单抗的纯度更高。因此在进行非还原单抗的纯度检测中，pH 6.0的样品缓冲液为最佳的前处理条件。     

Study of the separation of mouse monoclonal antibodies by pseudobioaffinity chromatography using matrix-linked histidine and histamine.

The selective retention of proteins on matrix-linked histidine has been shown to depend on chromatographic conditions: pH, temperature and ionic strength. An extension of this study to separate mouse monoclonal antibodies on histidyl-Sepharose is presented here; the roles of different functional groups such as imidazole, primary amine and carboxyl groups are elucidated by using histamine-Sepharose and histidine linked via the carboxyl group of the alpha-amino acid. We separated two monoclonal antibodies, immunoglobulin G1 (IgG1) from a culture supernatant and IgG2b from ascites fluid precipitated with 50% ammonium sulphate. The pseudoselective retention of monoclonal IgG1 on the three different matrices and IgG2b on histidyl-aminohexyl-Sepharose was achieved at pH 7.4. The purity of the final monoclonal antibody preparation determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis under reducing conditions proved the separation of the monoclonal antibodies (IgG1, IgG2b) from other contaminating proteins such as albumin and transferrin. Quantitation of the mouse monoclonal antibodies was carried out using enzyme-linked immunosorbent assay.     

Reversed-phase high-performance liquid chromatographic tryptic digest peptide map comparisons of monoclonal antibodies to human tumor necrosis factor.

An automatic computer technique was used to compare the retention times and ultraviolet spectra of sixty-two peaks in peptide maps of three monoclonal antibodies against human tumor necrosis factor (TNF) and one monoclonal antibody against recombinant factor VIII. The anti-TNF monoclonal, B6, which has an overlapping epitope with the anti-TNF monoclonal, A10G10, had a 90% peak match with A10G10. The anti-TNF monoclonal, A6, with a different epitope to TNF than A10G10, had only a 60% peak match. The A6 match to A10G10 was similar to the 50% peak match of the anti-factor VIII monoclonal with A10G10. The results of this study suggest that peptide mapping can be used as a quantitative characterization technique for comparing monoclonal antibodies.     

A New Alternative Tool to Analyse Glycosylation in Monoclonal Antibodies Based on Drop-Coating Deposition Raman imaging: A Proof of Concept

Glycosylation is considered a critical quality attribute of therapeutic proteins as it affects their stability, bioactivity, and safety. Hence, the development of analytical methods able to characterize the composition and structure of glycoproteins is crucial. Existing methods are time consuming, expensive, and require significant sample preparation, which can alter the robustness of the analyses. In this context, we developed a fast, direct, and simple drop-coating deposition Raman imaging (DCDR) method combined with multivariate curve resolution alternating least square (MCR-ALS) to analyze glycosylation in monoclonal antibodies (mAbs). A database of hyperspectral Raman imaging data of glycoproteins was built, and the glycoproteins were characterized by LC-FLR-MS as a reference method to determine the composition in glycans and monosaccharides. The DCDR method was used and allowed the separation of excipient and protein by forming a “coffee ring”. MCR-ALS analysis was performed to visualize the distribution of the compounds in the drop and to extract the pure spectral components. Further, the strategy of SVD-truncation was used to select the number of components to resolve by MCR-ALS. Raman spectra were processed by support vector regression (SVR). SVR models showed good predictive performance in terms of RMSECV, R²_CV.