Cloning and expression of a single-chain catalytic antibody that acts as a glutathione peroxidase mimic with high catalytic efficiency

2001 ◽  
Vol 359 (2) ◽  
pp. 369-374 ◽  
Author(s):  
Xiaojun REN ◽  
Shujuan GAO ◽  
Delin YOU ◽  
Hualiang HUANG ◽  
Zi LIU ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Glutathione Peroxidase ◽  
Binding Site ◽  
Active Form ◽  
Catalytic Efficiency ◽  
Catalytic Antibodies ◽  
Rabbit Liver ◽  
Cloning And Expression ◽  
Single Chain ◽  
Variable Regions

Glutathione peroxidase (GPX) has a powerful role in scavenging reactive oxygen species. In previous papers we have developed a new strategy for generating abzymes: the monoclonal antibody with a substrate-binding site is first prepared, then a catalytic group is incorporated into the monoclonal antibody's binding site by using chemical mutation [Luo, Zhu, Ding, Gao, Sun, Liu, Yang and Shen (1994) Biochem. Biophys. Res. Commun. 198, 1240–1247; Ding, Liu, Zhu, Luo, Zhao and Ni (1998) Biochem. J. 332, 251–255]. Since then we have established a series of catalytic antibodies capable of catalysing the decomposition of hydroperoxides by GSH. The monoclonal antibody 2F3 was raised against GSH-S-2,4-dinitrophenyl t-butyl ester and exhibited high catalytic efficiency, exceeding that of rabbit liver GPX, after chemical mutation. To produce pharmaceutical proteins and to study the reason why it exhibits high catalytic efficiency, we sequenced, cloned and expressed the variable regions of 2F3 antibody as a single-chain Fv fragment (2F3-scFv) in different bacterial strains. The amounts of 2F3-scFv proteins expressed from JM109 (DE3), BL21 (DE3), and BL21 (coden plus) were 5–10%, 15–20% and 25–30% of total bacterial proteins respectively. The 2F3-scFv was expressed as inclusion bodies, purified in the presence of 8M urea by Co2+-immobilized metal-affinity chromatography (IMAC) and renatured to the active form in vitro by gel filtration. The binding constants of the active 2F3-scFv for GSH and GSSG were 2.46×105M−1 and 1.03×105M−1 respectively, which were less by one order of magnitude than that of the intact 2F3 antibody. The active 2F3-scFv was converted into selenium-containing 2F3-scFv (Se-2F3-scFv) by chemical modification of the reactive serine; the GPX activity of the Se-2F3-scFv was 3394units/μmol, which approaches the activity of rabbit liver GPX.

scholarly journals The human fibrinolytic system is a target for the staphylococcal metalloprotease aureolysin

2008 ◽  
Vol 410 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Nathalie Beaufort ◽  
Piotr Wojciechowski ◽  
Christian P. Sommerhoff ◽  
Grzegorz Szmyd ◽  
Grzegorz Dubin ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Active Form ◽  
Catalytic Efficiency ◽  
Plasminogen Activator Inhibitor ◽  
Opportunistic Pathogen ◽  
Fibrinolytic System ◽  
Growth Media ◽  
Single Chain ◽  
Plasminogen Activator Inhibitor 1 ◽  
Proteolytic Activation

The major opportunistic pathogen Staphylococcus aureus utilizes the human fibrinolytic system for invasion and spread via plasmin(ogen) binding and non-proteolytic activation. Because S. aureus secretes several proteases recently proposed as virulence factors, we explored whether these enzymes could add to the activation of the host's fibrinolytic system. Exposure of human pro-urokinase [pro-uPA (where uPA is urokinase-type plasminogen activator)] to conditioned growth media from staphylococcal reference strains results in an EDTA-sensitive conversion of the single-chain zymogen into its two-chain active form, an activity not observed in an aureolysin-deficient strain. Using purified aureolysin, we verified the capacity of this thermolysin-like metalloprotease to activate pro-uPA, with a 2.6×103 M−1·s−1 catalytic efficiency. Moreover, activation also occurs in the presence of human plasma, as well as in conditioned growth media from clinical isolates. Finally, we establish that aureolysin (i) converts plasminogen into angiostatin and mini-plasminogen, the latter retaining its capacity to be activated by uPA and to hydrolyse fibrin, (ii) degrades the plasminogen activator inhibitor-1, and (iii) abrogates the inhibitory activity of α2-antiplasmin. Altogether, we propose that, in parallel with the staphylokinase-dependent activation of plasminogen, aureolysin may contribute significantly to the activation of the fibrinolytic system by S. aureus, and thus may promote bacterial spread and invasion.

scholarly journals Characterization of a Monoclonal Antibody and Its Single-Chain Antibody Fragment Recognizing the Nucleoside Triphosphatase/Helicase Domain of the Hepatitis C Virus Nonstructural 3 Protein

2000 ◽  
Vol 7 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Zhu-Xu Zhang ◽  
Una Lazdina ◽  
Margaret Chen ◽  
Darrell L. Peterson ◽  
Matti Sällberg
Keyword(s):  
Monoclonal Antibody ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Antibody Fragment ◽  
Expression Vectors ◽  
Helicase Domain ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Variable Regions

ABSTRACT We have produced a murine monoclonal antibody (MAb), ZX10, recognizing the NTPase/helicase domain of the hepatitis C virus (HCV) nonstructural 3 protein (NS3), from which we designed a single-chain variable fragment (ScFv). The ZX10 MAb recognized a discontinuous epitope of the NTPase/helicase domain, of which the linear sequence GEIPFYGKAIPL at residues 1371 to 1382 constitutes one part. cDNAs from variable regions coding for the heavy and light chains were cloned, sequenced, and assembled into the NS3-ScFv, which was inserted into procaryotic and eucaryotic expression vectors.Escherichia coli-expressed NS3-ScFv inhibited the binding of the ZX10 MAb to NS3, confirming a retained specificity. However, the ability to bind the peptide 1371–1382 had been lost. In vitro-translated NS3-ScFv and HCV NS3/NS4A were coprecipitated by antibodies to HCV NS4A, confirming the in vitro activity of the NS3 ScFv. Thus, we have designed a functional NS3 NTPase/helicase domain-specific ScFv which should be evaluated further with respect to disturbing enzymatic functions of the NS3 protein.

scholarly journals Generation and functional characterization of a single-chain variable fragment (scFv) of the anti-FGF2 3F12E7 monoclonal antibody

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rodrigo Barbosa de Aguiar ◽  
Tábata de Almeida da Silva ◽  
Bruno Andrade Costa ◽  
Marcelo Ferreira Marcondes Machado ◽  
Renata Yoshiko Yamada ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Functional Characterization ◽  
Single Chain Variable Fragment ◽  
Single Chain ◽  
Variable Regions ◽  
Recombinant Scfv ◽  
Antitumor Potential ◽  
Single Chain Variable Fragments ◽  
Binding Determinants

AbstractSingle-chain variable fragments (scFvs) are small-sized artificial constructs composed of the immunoglobulin heavy and light chain variable regions connected by a peptide linker. We have previously described an anti-fibroblast growth factor 2 (FGF2) immunoglobulin G (IgG) monoclonal antibody (mAb), named 3F12E7, with notable antitumor potential revealed by preclinical assays. FGF2 is a known angiogenesis-associated molecule implicated in tumor progression. In this report, we describe a recombinant scFv format for the 3F12E7 mAb. The results demonstrate that the generated 3F12E7 scFv, although prone to aggregation, comprises an active anti-FGF2 product that contains monomers and small oligomers. Functionally, the 3F12E7 scFv preparations specifically recognize FGF2 and inhibit tumor growth similar to the corresponding full-length IgG counterpart in an experimental model. In silico molecular analysis provided insights into the aggregation propensity and the antigen-recognition by scFv units. Antigen-binding determinants were predicted outside the most aggregation-prone hotspots. Overall, our experimental and prediction dataset describes an scFv scaffold for the 3F12E7 mAb and also provides insights to further engineer non-aggregated anti-FGF2 scFv-based tools for therapeutic and research purposes.

scholarly journals The V1V2 Region of HIV-1 gp120 Forms a Five-Stranded Beta Barrel

2015 ◽  
Vol 89 (15) ◽  
pp. 8003-8010 ◽  
Author(s):  
Ruimin Pan ◽  
Miroslaw K. Gorny ◽  
Susan Zolla-Pazner ◽  
Xiang-Peng Kong
Keyword(s):  
Crystal Structure ◽  
Monoclonal Antibody ◽  
Binding Site ◽  
Phase Iii ◽  
Antigenic Structure ◽  
Variable Regions ◽  
Beta Barrel ◽  
Integrin Binding Site ◽  
Hiv 1 ◽  
V1v2 Region

ABSTRACTThe region consisting of the first and second variable regions (V1V2) of gp120 plays vital roles in the functioning of the HIV-1 envelope (Env). V1V2, which harbors multiple glycans and is highly sequence diverse, is located at the Env apex and stabilizes the trimeric gp120 spike on the virion surface. It shields V3 and the coreceptor binding sites in the prefusion state and exposes them upon CD4 binding. Data from the RV144 human HIV-1 vaccine trial suggested that antibody responses targeting the V1V2 region inversely correlated with the risk of infection; thus, understanding the antigenic structure of V1V2 can contribute to vaccine design. We have determined a crystal structure of a V1V2 scaffold molecule (V1V2ZM109-1FD6) in complex with 830A, a human monoclonal antibody that recognizes a V1V2 epitope overlapping the integrin-binding motif in V2. The structure revealed that V1V2 assumes a five-stranded beta barrel structure with the region of the integrin-binding site (amino acids [aa] 179 to 181) included in a “kink” followed by an extra beta strand. The complete barrel structure naturally presents the glycans on its outer surface and packs into its core conserved hydrophobic residues, including the Ile at position 181 which was highly correlated with vaccine efficacy in RV144. The epitope of monoclonal antibody 830A is discontinuous and composed of three segments: (i) Thr175, Tyr177, Leu179, and Asp180at the kink overlapping the integrin-binding site; (ii) Arg153and Val154in V1; and (iii) Ile194at the C terminus of V2. This report thus provides the atomic details of the immunogenic “V2i epitope.”IMPORTANCEData from the RV144 phase III clinical trial suggested that the presence of antibodies to the first and second variable regions (V1V2) of gp120 was associated with the modest protection afforded by the vaccine. V1V2 is a highly variable and immunogenic region of HIV-1 surface glycoprotein gp120, and structural information about this region and its antigenic landscape will be crucial in the design of an effective HIV-1 vaccine. We have determined a crystal structure of V1V2 in complex with human MAb 830A and have shown that MAb 830A recognizes a region overlapping the α4β7 integrin-binding site. We also showed that V1V2 forms a 5-stranded beta barrel, an elegant structure allowing sequence variations in the strand-connecting loops while preserving a conserved core.

scholarly journals Mechanism of SARS-CoV-2 polymerase stalling by remdesivir

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Goran Kokic ◽  
Hauke S. Hillen ◽  
Dimitry Tegunov ◽  
Christian Dienemann ◽  
Florian Seitz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Binding Site ◽  
Molecular Mechanism ◽  
Active Center ◽  
Rna Synthesis ◽  
Active Form ◽  
Nucleoside Triphosphate ◽  
Rna Dependent Rna Polymerase ◽  
Cryo Electron Microscopy

AbstractRemdesivir is the only FDA-approved drug for the treatment of COVID-19 patients. The active form of remdesivir acts as a nucleoside analog and inhibits the RNA-dependent RNA polymerase (RdRp) of coronaviruses including SARS-CoV-2. Remdesivir is incorporated by the RdRp into the growing RNA product and allows for addition of three more nucleotides before RNA synthesis stalls. Here we use synthetic RNA chemistry, biochemistry and cryo-electron microscopy to establish the molecular mechanism of remdesivir-induced RdRp stalling. We show that addition of the fourth nucleotide following remdesivir incorporation into the RNA product is impaired by a barrier to further RNA translocation. This translocation barrier causes retention of the RNA 3ʹ-nucleotide in the substrate-binding site of the RdRp and interferes with entry of the next nucleoside triphosphate, thereby stalling RdRp. In the structure of the remdesivir-stalled state, the 3ʹ-nucleotide of the RNA product is matched and located with the template base in the active center, and this may impair proofreading by the viral 3ʹ-exonuclease. These mechanistic insights should facilitate the quest for improved antivirals that target coronavirus replication.

scholarly journals Single Chain Variable Fragment Fused to Maltose Binding Protein: A Modular Nanocarrier Platform for the Targeted Delivery of Antitumorals

2021 ◽  
Author(s):  
Francisco J. Reche-Perez ◽  
Simona Plesselova ◽  
Eduardo De los Reyes-Berbel ◽  
Mariano Ortega-Muñoz ◽  
F. Javier Lopez-Jaramillo ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Targeted Delivery ◽  
Specific Binding ◽  
Protein A ◽  
Antibody Fragments ◽  
Single Chain Variable Fragment ◽  
Single Chain ◽  
Binding Properties ◽  
Single Chain Variable Fragments ◽  
Selective Delivery

The use of the specific binding properties of monoclonal antibody fragments such as single-chain variable fragments (ScFv) for the selective delivery of antitumor therapeutics for cancer cells is attractive due...

scholarly journals A scDb-based trivalent bispecific antibody for T-cell-mediated killing of HER3-expressing cancer cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nadine Aschmoneit ◽  
Sophia Steinlein ◽  
Lennart Kühl ◽  
Oliver Seifert ◽  
Roland E. Kontermann
Keyword(s):  
T Cell ◽  
Binding Site ◽  
Cancer Cell ◽  
Cancer Progression ◽  
T Cell Activation ◽  
Cell Activation ◽  
Egf Receptor ◽  
Bispecific Antibodies ◽  
Target Cells ◽  
Single Chain

AbstractHER3 is a member of the EGF receptor family and elevated expression is associated with cancer progression and therapy resistance. HER3-specific T-cell engagers might be a suitable treatment option to circumvent the limited efficacy observed for HER3-blocking antibodies in clinical trials. In this study, we developed bispecific antibodies for T-cell retargeting to HER3-expressing tumor cells, utilizing either a single-chain diabody format (scDb) with one binding site for HER3 and one for CD3 on T-cells or a trivalent bispecific scDb-scFv fusion protein exhibiting an additional binding site for HER3. The scDb-scFv showed increased binding to HER3-expressing cancer cell lines compared to the scDb and consequently more effective T-cell activation and T-cell proliferation. Furthermore, the bivalent binding mode of the scDb-scFv for HER3 translated into more potent T-cell mediated cancer cell killing, and allowed to discriminate between moderate and low HER3-expressing target cells. Thus, our study demonstrated the applicability of HER3 for T-cell retargeting with bispecific antibodies, even at moderate expression levels, and the increased potency of an avidity-mediated specificity gain, potentially resulting in a wider safety window of bispecific T-cell engaging antibodies targeting HER3.

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