新型HIV-1蛋白酶抑制剂的合成

HIV-1蛋白酶为成熟病毒颗粒的正常组装提供必需的结构蛋白和功能蛋白,因此,HIV-1蛋白酶抑制剂可有效阻止病毒的进一步感染。然而,耐药性一直是抗HIV药物面临的一个关键科学问题,设计一类具有新型骨架特征的HIV-1蛋白酶抑制剂不失为一种好的解决方案。以Darunavir为先导化合物,运用骨架跃迁和拼合等药物设计策略,设计合成了3个结构新颖的化合物,均未见文献报道,目标化合物经~1HNMR、~(13)CNMR和MS确证。     

Bioorthogonal Chemistry Enables Single-Molecule FRET Measurements of Catalytically Active Protein Disulfide Isomerase

Folding of newly synthesized proteins in the endoplasmic reticulum is assisted by several families of enzymes. One such family is the protein disulfide isomerases (PDIs). PDIs are oxidoreductases, capable of forming new disulfide bonds or breaking existing ones. Structural information on PDIs unbound and bound to substrates is highly desirable for developing targeted therapeutics, yet it has been difficult to obtain by using traditional approaches because of their relatively large size and remarkable flexibility. Single-molecule FRET (smFRET) could be a powerful tool to study PDIs’ structure and dynamics under conditions relevant to physiology, but its implementation has been hindered by technical challenges of position-specific fluorophore labeling. We have overcome this limitation by site-specifically engineering fluorescent dyes into human PDI, the founding member of the family. Proof-of-concept smFRET measurements of catalytically active PDI demonstrate, for the first time, the feasibility of this approach, expanding the toolkit for structural studies of PDIs.     

Pharmacokinetic Parameters of HIV-1 Protease Inhibitors

Since the beginning of the HIV epidemic, research has been carried out to control the virus. Understanding the mechanisms of replication has given access to the various classes of drugs that over time have transformed AIDS into a manageable chronic disease. The class of protease inhibitors (PIs) gained notice in anti-retroviral therapy, once it was found that peptidomimetic molecules act by blocking the active catalytic center of the aspartic protease, which is directly related to HIV maturation. However, mutations in enzymatic internal residues are the biggest issue for these drugs, because a small change in biochemical interaction can generate resistance. Low plasma concentrations of PIs favor viral natural selection; high concentrations can inhibit even partially resistant enzymes. Food-drug/drug-drug interactions can decrease the bioavailability of PIs and are related to many side effects. Therefore, this review summarizes the pharmacokinetic properties of current PIs, the changes when pharmacological boosters are used and also lists the major mutations to help understanding of how long the continuous treatment can ensure a low viral load in patients.     

Design,Synthesis and X-Ray Structural Studies of Potent HIV-1 Protease Inhibitors Containing C-4 Substituted Tricyclic Hexahydro-Furofuran Derivatives as P2 Ligands

The design, synthesis, X-ray structural, and biological evaluation of a series of highly potent HIV-1 protease inhibitors are reported herein. These inhibitors incorporate novel cyclohexane-fused tricyclic bis-tetrahydrofuran as P2 ligands in combination with a variety of P1 and P2′ ligands. The inhibitor with a difluoromethylphenyl P1 ligand and a cyclopropylaminobenzothiazole P2′ ligand exhibited the most potent antiviral activity. Also, it maintained potent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The corresponding inhibitor with an enantiomeric ligand was significantly less potent in these antiviral assays. The new P2 ligands were synthesized in optically active form using enzymatic desymmetrization of meso-diols as the key step. To obtain molecular insight, two high-resolution X-ray structures of inhibitor-bound HIV-1 protease were determined and structural analyses have been highlighted.     

Design and Evaluation of Novel HIV-1 Protease Inhibitors Containing Phenols or Polyphenols as P2 Ligands with High Activity against DRV-Resistant HIV-1 Variants

With the increasing prevalence of drug-resistant variants, novel potent HIV-1 protease inhibitors with broad-spectrum antiviral activity against multidrug-resistant causative viruses are urgently needed. Herein, we designed and synthesized a new series of HIV-1 protease inhibitors with phenols or polyphenols as the P2 ligands and a variety of sulfonamide analogs as the P2′ ligands. A number of these new inhibitors showed superb enzymatic inhibitory activity and antiviral activity. In particular, inhibitors 15d and 15f exhibited potent enzymatic inhibitory activity in the low picomolar range, and the latter showed excellent activity against the Darunavir-resistant HIV-1 variant. Furthermore, the molecular modeling studies provided insight into the ligand-binding site interactions between inhibitors and the enzyme cavity, and they sparked inspiration for the further optimization of potent inhibitors.     

Potential Resistance of SARS-CoV-2 Main Protease (Mpro) against Protease Inhibitors: Lessons Learned from HIV-1 Protease

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome 2 (SARS-CoV-2), has been one of the most devastating pandemics of recent times. The lack of potent novel antivirals had led to global health crises; however, emergence and approval of potent inhibitors of the viral main protease (Mpro), such as Pfizer’s newly approved nirmatrelvir, offers hope not only in the therapeutic front but also in the context of prophylaxis against the infection. By their nature, RNA viruses including human immunodeficiency virus (HIV) have inherently high mutation rates, and lessons learnt from previous and currently ongoing pandemics have taught us that these viruses can easily escape selection pressure through mutation of vital target amino acid residues in monotherapeutic settings. In this paper, we review nirmatrelvir and its binding to SARS-CoV-2 Mpro and draw a comparison to inhibitors of HIV protease that were rendered obsolete by emergence of resistance mutations, emphasizing potential pitfalls in the design of inhibitors that may be of important relevance to the long-term use of novel inhibitors against SARS-CoV-2.     

应用毕赤酵母表达中国株HIV-1核心蛋白Gag

目的 构建含HIV-1Gag全长基因的重组酵母表达质粒pPICGAG，并在毕赤酵母中进行表达。方法用Not I和XhoI将含HIV－1 Gag全长基因的质粒pKSGAG双酶切后，克隆到酵母表达载体pPIC9中，构建了重组表达质粒 pPICGAG。pPICGAG用 SacI线性化后，电转化毕赤酵母 GS115，PCR鉴定阳性酵母转化子，并分别将PCR阳性的酵母转化子在BMGY和BMMY培养基中进行诱导表达，表达产物进行SDS-PAGE电泳分析。结果 酵母转化子的整合率为72．7％。SDS-PAGE结果显示表达蛋白的相对分子质量为55000左右，与预计计算的值相同。Western blot结果显示表达蛋白能与单克隆抗体发生特异性反应。结论 在毕赤酵母中成功地表达了HIV-1核心蛋白Gag，且表达的蛋白具有良好的反应原性和特异性。     

Potent HIV-1 Protease Inhibitors Containing Carboxylic and Boronic Acids: Effect on Enzyme Inhibition and Antiviral Activity and Protein-Ligand X-ray Structural Studies

We report the synthesis and biological evaluation of phenylcarboxylic acid and phenylboronic acid containing HIV-1 protease inhibitors and their functional effect on enzyme inhibition and antiviral activity in MT-2 cell lines. Inhibitors bearing bis-THF ligand as P2 ligand and phenylcarboxylic acids and carboxamide as the P2′ ligands, showed very potent HIV-1 protease inhibitory activity. However, carboxylic acid containing inhibitors showed very poor antiviral activity relative to carboxamide-derived inhibitors which showed good antiviral IC₅₀ value. Boronic acid derived inhibitor with bis-THF as the P2 ligand showed very potent enzyme inhibitory activity, but it showed lower antiviral activity than darunavir in the same assay. Boronic acid containing inhibitor with a P2-Crn-THF ligand also showed potent enzyme K_i but significantly decreased antiviral activity. We have evaluated antiviral activity against a panel of highly drug-resistant HIV-1 variants. One of the inhibitors maintained good antiviral activity against HIV_DRV^R_P20 and HIV_DRV^R_P30 viruses. We have determined high resolution X-ray structures of two synthetic inhibitors bound to HIV-1 protease and obtained molecular insight into the ligand-binding site interactions.     

HIV-1C亚型调控蛋白Nef在大肠杆菌中的表达

目的表达人免疫缺陷病毒1型C亚型调控蛋白Nef,为研制HIV疫苗寻找新的途径。方法通过PCR扩增,获得HIV-1C亚型Nef基因片段,并将其克隆到原核表达载体pGEX-5X-1中,转化大肠杆菌BL21(DE3),IPTG诱导表达后,以SDS-PAGE和Westernblot分析表达产物。结果表达产物是相对分子质量为50000的GST融合蛋白,且能与p27单克隆抗体发生特异性反应。结论重组Nef蛋白在大肠杆菌中得到了有效表达。     

人类免疫缺陷病毒1型C亚型核心蛋白(Gag)在大肠杆菌中的表达

目的表达人免疫缺陷病毒1型C亚型核心蛋白Gag,为HIV感染的诊断和疫苗的研制奠定基础。方法通过PCR扩增获得HIV1gag基因片段,并将其克隆到原核表达载体pGEX5X1的tac启动子下游,构建重组表达质粒,转化大肠杆菌BL21(DE3),IPTG诱导表达,以SDSPAGE和Westernblot分析验证其表达产物。结果表达产物是相对分子质量为82000的GST融合蛋白,且能与抗p24单克隆抗体发生特异性反应。结论重组Gag蛋白在大肠杆菌中得到了有效表达,且具有良好的抗原性,可进一步用于HIV感染及动物免疫等方面的研究。     

PEG相转移催化法合成1-羟甲基苯并三氮唑

研究了在相转移催化剂聚乙二醇(PEG)存在下,苯并三氮唑和甲醛进行亲核加成制备1-羟甲基苯并三氮唑的合成条件。讨论了聚乙二醇分子量、反应物物质的量比、反应温度、反应时间等因素对目标产物收率的影响,得出适合的操作条件为:n(苯并三氮唑):n(甲醛):n(PEG-1000)=1:2:0.01、反应温度25℃、反应时间0.5 h、产品收率达98%。该合成方法具有反应时间短、操作简便、能耗小、溶剂量少等优点。     

HIV-1 Gag蛋白在重组痘苗病毒中的高效表达及其特性分析

在构建3株人Ⅰ型免疫缺陷病毒（HIV－1）Gag基因重组痘苗病毒的基础上,实现了Gag蛋白的高效表达,3株重组病毒在感染细胞中表达量分别为14．7、6．0和4.5μg／106细胞／20h,接近杆状病毒的表达水平。表达的重组蛋白可形成病毒样粒子（VLP）,并可诱导小鼠产生抗HIV抗体。     

表达HIV-1 gp160膜蛋白靶细胞的制备及鉴定

目的获得表达INV-1 gp160膜蛋白的靶细胞,用于HIV-1特异性细胞毒性淋巴细胞(CTL)和抗HIV-1重组毒素细胞杀伤活性检测。方法采用PCR方法,从质粒pJen 10中扩增HIV-1 gp160基因,插入pGEM-T载体,测序后克隆入pIRESl neo载体中构建成重组质粒pIRE160,酶切鉴定正确后,转染人肝癌细胞(SMMG-7721),CA18加压筛选至细胞不再死亡为止,并采用Western blot和间接免疫荧光法对制备的靶细胞进行检测。结果HIV-1 gp160在SMMC7721表面表达,并裂解为gp120和gp41蛋白。结论已成功得到稳定表达HIV-1 gp160的靶细胞,且表达的蛋白具有良好的特异性。     

相转移催化合成1-羟基苯并三氮唑

研究了在相转移催化剂聚乙二醇(PEG)800存在下,邻硝基氯苯和水合肼反应生成1-羟基苯并三氮唑的工艺过程。讨论了催化剂种类、原料摩尔比、反应温度、反应时间、搅拌速度等因素对目的产品收率的影响,得出适合的操作条件为:n(邻硝基氯苯)∶n(水合肼)∶n(PEG-800)=1∶4∶0.03、反应温度110℃、反应时间5h、搅拌速度500r/min,产品收率达98.1%。该合成方法具有工艺原料摩尔比小、反应时间短、操作简便、能耗小等优点。     

HIV-1 Tat Protein Enters Dysfunctional Endothelial Cells via Integrins and Renders Them Permissive to Virus Replication

Previous work has shown that the Tat protein of Human Immunodeficiency Virus (HIV)-1 is released by acutely infected cells in a biologically active form and enters dendritic cells upon the binding of its arginine-glycine-aspartic acid (RGD) domain to the α5β1, αvβ3, and αvβ5 integrins. The up-regulation/activation of these integrins occurs in endothelial cells exposed to inflammatory cytokines that are increased in HIV-infected individuals, leading to endothelial cell dysfunction. Here, we show that inflammatory cytokine-activated endothelial cells selectively bind and rapidly take up nano-micromolar concentrations of Tat, as determined by flow cytometry. Protein oxidation and low temperatures reduce Tat entry, suggesting a conformation- and energy-dependent process. Consistently, Tat entry is competed out by RGD-Tat peptides or integrin natural ligands, and it is blocked by anti-α5β1, -αvβ3, and -αvβ5 antibodies. Moreover, modelling–docking calculations identify a low-energy Tat-αvβ3 integrin complex in which Tat makes contacts with both the αv and β3 chains. It is noteworthy that internalized Tat induces HIV replication in inflammatory cytokine-treated, but not untreated, endothelial cells. Thus, endothelial cell dysfunction driven by inflammatory cytokines renders the vascular system a target of Tat, which makes endothelial cells permissive to HIV replication, adding a further layer of complexity to functionally cure and/or eradicate HIV infection.     

Chemical Synthesis of Integral Membrane Proteins: Methods and Applications

The development of efficient chemical methods for total synthesis or semisynthesis of integral membrane proteins is an important challenge at the interface between chemistry and biology. This review outlines the recent advances in the synthesis of integral membrane proteins, with particular focus on the methods for difficult peptide synthesis, purification, and enhancement of peptide solubility under the ligation conditions. The applications of these methods to the synthesis of integral membrane proteins with one or multiple transmembrane domains are also described.     

Chemical synthesis and expression of the HIV-1 Rev protein

The HIV-1 Rev protein is responsible for shuttling partially spliced and unspliced viral mRNA out of the nucleus. This is a crucial step in the HIV-1 lifecycle, thus making Rev an attractive target for the design of anti-HIV drugs. Despite its importance, there is a lack of structural, biophysical, and quantitative information about Rev. This is mainly because of its tendency to undergo self-assembly and aggregation; this makes it very difficult to express and handle. To address this knowledge gap, we have developed two new highly efficient and reproducible methods to prepare Rev in large quantities for biochemical and structural studies: 1) Chemical synthesis by using native chemical ligation coupled with desulfurization. Notably, we have optimized our synthesis to allow for a one-pot approach for the ligation and desulfurization steps; this reduced the number of purification steps and enabled the obtaining of desired protein in excellent yield. Several challenges emerged during the design of this Rev synthesis, such as racemization, reduced solubility, formylation during thioester synthesis, and the necessity for using orthogonal protection during desulfurization; solutions to these problems were found. 2) A new method for expression and purification by using a vector that contained an HLT tag, followed by purification with a Ni column, a cation exchange column, and gel filtration. Both methods yielded highly pure and folded Rev. The CD spectra of the synthetic and recombinant Rev proteins were identical, and consistent with a predominantly helical structure. These advances should facilitate future studies that aim at a better understanding of the structure and function of the protein.     

蛋白酶产生菌LN02发酵玉米黄粉蛋白的条件优化

通过单因素实验和正交实验初步优化了蛋白酶产生菌LN02发酵玉米黄粉蛋白的条件。结果表明,菌株LN02发酵玉米黄粉蛋白的最佳条件为：初始pH值5.5、装液量60 mL/250 mL三角瓶、发酵温度35℃、发酵时间5 d。