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Spiegelberg D, Stenberg J, Richalet P, Vanhove M. K D determination from time-resolved experiments on live cells with LigandTracer and reconciliation with end-point flow cytometry measurements. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:979-991. [PMID: 34302187 PMCID: PMC8448686 DOI: 10.1007/s00249-021-01560-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 06/16/2021] [Accepted: 07/01/2021] [Indexed: 11/30/2022]
Abstract
Design of next-generation therapeutics comes with new challenges and emulates technology and methods to meet them. Characterizing the binding of either natural ligands or therapeutic proteins to cell-surface receptors, for which relevant recombinant versions may not exist, represents one of these challenges. Here we report the characterization of the interaction of five different antibody therapeutics (Trastuzumab, Rituximab, Panitumumab, Pertuzumab, and Cetuximab) with their cognate target receptors using LigandTracer. The method offers the advantage of being performed on live cells, alleviating the need for a recombinant source of the receptor. Furthermore, time-resolved measurements, in addition to allowing the determination of the affinity of the studied drug to its target, give access to the binding kinetics thereby providing a full characterization of the system. In this study, we also compared time-resolved LigandTracer data with end-point KD determination from flow cytometry experiments and hypothesize that discrepancies between these two approaches, when they exist, generally come from flow cytometry titration curves being acquired prior to full equilibration of the system. Our data, however, show that knowledge of the kinetics of the interaction allows to reconcile the data obtained by flow cytometry and LigandTracer and demonstrate the complementarity of these two methods.
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Affiliation(s)
- Diana Spiegelberg
- Department of Surgical Sciences, Uppsala University, 751 85, Uppsala, Sweden
| | - Jonas Stenberg
- Ridgeview Instruments AB, Skillsta 4, 740 20, Vänge, Sweden.,A3P Biomedical AB, Vallongatan 1, 752 28, Uppsala, Sweden
| | | | - Marc Vanhove
- Marc Vanhove Consultancy, 4100, Boncelles, Belgium. .,Oxurion N.V., Gaston Geenslaan 1, 3001, Leuven, Belgium.
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2
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Huetter J, Gritzan U, Gutcher I, Doecke WD, Luetke-Eversloh MV, Golfier S, Roider HG, Frisk AL, Hunter J, Pow A, Drake A, Levine Z, Levy O, Azulay M, Barbiro I, Cojocaru G, Vaknin I, Kreft B, Roese L. Characterization of BAY 1905254, an Immune Checkpoint Inhibitor Targeting the Immunoglobulin-Like Domain Containing Receptor 2 (ILDR2). Cancer Immunol Res 2020; 8:895-911. [DOI: 10.1158/2326-6066.cir-19-0321] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 11/15/2019] [Accepted: 04/13/2020] [Indexed: 11/16/2022]
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Abstract
Monoclonal antibodies (MAbs) have become a substantial part of many pharmaceutical company portfolios. However, the development process of MAbs for clinical use is quite different than for small-molecule drugs. MAb development programs require careful interdisciplinary evaluations to ensure the pharmacology of both the MAb and the target antigen are well-understood. Selection of appropriate preclinical species must be carefully considered and the potential development of anti-drug antibodies (ADA) during these early studies can limit the value and complicate the performance and possible duration of preclinical studies. In human studies, many of the typical pharmacology studies such as renal or hepatic impairment evaluations may not be needed but the pharmacokinetics and pharmacodynamics of these agents is complex, often necessitating more comprehensive evaluation of clinical data and more complex bioanalytical assays than might be used for small molecules. This paper outlines concerns and strategies for development of MAbs from the early in vitro assessments needed through preclinical and clinical development. This review focuses on how to develop, submit, and comply with regulatory requirements for MAb therapeutics.
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4
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Erasmus MF, Matlawska-Wasowska K, Kinjyo I, Mahajan A, Winter SS, Xu L, Horowitz M, Lidke DS, Wilson BS. Dynamic pre-BCR homodimers fine-tune autonomous survival signals in B cell precursor acute lymphoblastic leukemia. Sci Signal 2016; 9:ra116. [PMID: 27899526 DOI: 10.1126/scisignal.aaf3949] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The pre-B cell receptor (pre-BCR) is an immature form of the BCR critical for early B lymphocyte development. It is composed of the membrane-bound immunoglobulin (Ig) heavy chain, surrogate light chain components, and the signaling subunits Igα and Igβ. We developed monovalent quantum dot (QD)-labeled probes specific for Igβ to study the behavior of pre-BCRs engaged in autonomous, ligand-independent signaling in live B cells. Single-particle tracking revealed that QD-labeled pre-BCRs engaged in transient, but frequent, homotypic interactions. Receptor motion was correlated at short separation distances, consistent with the formation of dimers and higher-order oligomers. Repeated encounters between diffusing pre-BCRs appeared to reflect transient co-confinement in plasma membrane domains. In human B cell precursor acute lymphoblastic leukemia (BCP-ALL) cells, we showed that frequent, short-lived, homotypic pre-BCR interactions stimulated survival signals, including expression of BCL6, which encodes a transcriptional repressor. These survival signals were blocked by inhibitory monovalent antigen-binding antibody fragments (Fabs) specific for the surrogate light chain components of the pre-BCR or by inhibitors of the tyrosine kinases Lyn and Syk. For comparison, we evaluated pre-BCR aggregation mediated by dimeric galectin-1, which has binding sites for carbohydrate and for the surrogate light chain λ5 component. Galectin-1 binding resulted in the formation of large, highly immobile pre-BCR aggregates, which was partially relieved by the addition of lactose to prevent the cross-linking of galectin-BCR complexes to other glycosylated membrane components. Analysis of the pre-BCR and its signaling partners suggested that they could be potential targets for combination therapy in BCP-ALL.
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Affiliation(s)
- M Frank Erasmus
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Ksenia Matlawska-Wasowska
- UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,Department of Pediatrics, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Ichiko Kinjyo
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Avanika Mahajan
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Stuart S Winter
- UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,Department of Pediatrics, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Li Xu
- Sea Lane Biotechnologies, 2450 Bayshore Parkway, Mountain View, CA 94043, USA
| | - Michael Horowitz
- Sea Lane Biotechnologies, 2450 Bayshore Parkway, Mountain View, CA 94043, USA
| | - Diane S Lidke
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Bridget S Wilson
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA. .,UNM Comprehensive Cancer Center, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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5
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Zhu Y, Ksibe AZ, Schäfer H, Blindauer CA, Bugg TDH, Chen Y. O2-independent demethylation of trimethylamineN-oxide by Tdm ofMethylocella silvestris. FEBS J 2016; 283:3979-3993. [DOI: 10.1111/febs.13902] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/09/2016] [Accepted: 09/15/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Yijun Zhu
- School of Life Sciences; University of Warwick; Coventry UK
| | - Amira Z. Ksibe
- Department of Chemistry; University of Warwick; Coventry UK
| | | | | | | | - Yin Chen
- School of Life Sciences; University of Warwick; Coventry UK
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6
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Schwickart M, Chavez C, Henderson S, Vainshtein I, Standifer N, DelNagro C, Mehrzai F, Schneider A, Roskos L, Liang M. Evaluation of assay interference and interpretation of CXCR4 receptor occupancy results in a preclinical study with MEDI3185, a fully human antibody to CXCR4. CYTOMETRY PART B-CLINICAL CYTOMETRY 2015; 90:209-19. [PMID: 26384735 PMCID: PMC5064743 DOI: 10.1002/cyto.b.21327] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 08/05/2015] [Accepted: 09/10/2015] [Indexed: 12/02/2022]
Abstract
Background Receptor occupancy (RO) assays provide a means to measure the direct interaction of therapeutics with their cell surface targets. Free receptor assays quantify cell‐surface receptors not bound by a therapeutic while total receptor assays quantify the amount of target on the cell surface. Methods We developed both a flow cytometry‐based free RO assay to detect free surface CXCR4, and a total surface CXCR4 assay. In an effort to evaluate potential displacement interference, we performed in vitro experiments to compare on‐cell affinity with the IC50 values from in vitro and in vivo from the free CXCR4 assay. We determined free and total surface CXCR4 on circulating blood cells in cynomolgus monkeys dosed with MEDI3185, a fully human monoclonal antibody to CXCR4. Results We devised an approach to evaluate displacement interference during assay development and showed that our free assay demonstrated little to no displacement interference. After dosing cynomolgus monkeys with MEDI3185, we observed dose‐dependence in the magnitude and duration of receptor occupancy and found CXCR4 to increase on lymphocytes, monocytes, and granulocytes. In a multiple dose study, we observed time points where surface CXCR4 appeared fully occupied but MEDI3185 was not detectable in serum. These paradoxical results represented a type of assay interference, and by comparing pharmacokinetic, ADA and total CXCR4 results, the most likely reason for the free CXCR4 results was the emergence of neutralizing anti‐drug antibodies (ADA). The total CXCR4 assay was unaffected by ADA and provided a reliable marker of target modulation in both in vivo studies. © 2015 The Authors Cytometry Part B: Clinical Cytometry Published byWiley Periodicals, Inc.
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Affiliation(s)
- Martin Schwickart
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Carlos Chavez
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Simon Henderson
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Inna Vainshtein
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Nathan Standifer
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | | | - Freshta Mehrzai
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Amy Schneider
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Lorin Roskos
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
| | - Meina Liang
- Clinical Pharmacology & DMPK, Medimmune, LLC, Mountain View, California, 94043
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7
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Kim SY, Theunissen JW, Balibalos J, Liao-Chan S, Babcock MC, Wong T, Cairns B, Gonzalez D, van der Horst EH, Perez M, Levashova Z, Chinn L, D'Alessio JA, Flory M, Bermudez A, Jackson DY, Ha E, Monteon J, Bruhns MF, Chen G, Migone TS. A novel antibody-drug conjugate targeting SAIL for the treatment of hematologic malignancies. Blood Cancer J 2015; 5:e316. [PMID: 26024286 PMCID: PMC4476018 DOI: 10.1038/bcj.2015.39] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 04/17/2015] [Indexed: 01/21/2023] Open
Abstract
Although several new therapeutic approaches have improved outcomes in the treatment of hematologic malignancies, unmet need persists in acute myeloid leukemia (AML), multiple myeloma (MM) and non-Hodgkin's lymphoma. Here we describe the proteomic identification of a novel cancer target, SAIL (Surface Antigen In Leukemia), whose expression is observed in AML, MM, chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). While SAIL is widely expressed in CLL, AML, MM, DLBCL and FL patient samples, expression in cancer cell lines is mostly limited to cells of AML origin. We evaluated the antitumor activity of anti-SAIL monoclonal antibodies, 7-1C and 67-7A, conjugated to monomethyl auristatin F. Following internalization, anti-SAIL antibody–drug conjugates (ADCs) exhibited subnanomolar IC50 values against AML cell lines in vitro. In pharmacology studies employing AML cell line xenografts, anti-SAIL ADCs resulted in significant tumor growth inhibition. The restricted expression profile of this target in normal tissues, the high prevalence in different types of hematologic cancers and the observed preclinical activity support the clinical development of SAIL-targeted ADCs.
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Affiliation(s)
- S Y Kim
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - J-W Theunissen
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - J Balibalos
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - S Liao-Chan
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - M C Babcock
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - T Wong
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - B Cairns
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - D Gonzalez
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - E H van der Horst
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - M Perez
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - Z Levashova
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - L Chinn
- Department of Preclinical Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - J A D'Alessio
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - M Flory
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - A Bermudez
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - D Y Jackson
- Department of Chemistry, Igenica Biotherapeutics, Burlingame, CA, USA
| | - E Ha
- Department of Chemistry, Igenica Biotherapeutics, Burlingame, CA, USA
| | - J Monteon
- Department of Process Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - M F Bruhns
- Department of Process Development, Igenica Biotherapeutics, Burlingame, CA, USA
| | - G Chen
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
| | - T-S Migone
- Department of Biology, Igenica Biotherapeutics, Burlingame, CA, USA
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8
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Chen LY. Computing membrane-AQP5-phosphatidylserine binding affinities with hybrid steered molecular dynamics approach. Mol Membr Biol 2015; 32:19-25. [PMID: 25955791 DOI: 10.3109/09687688.2015.1006275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In order to elucidate how phosphatidylserine (PS6) interacts with AQP5 in a cell membrane, we developed a hybrid steered molecular dynamics (hSMD) method that involved: (1) Simultaneously steering two centers of mass of two selected segments of the ligand, and (2) equilibrating the ligand-protein complex with and without biasing the system. Validating hSMD, we first studied vascular endothelial growth factor receptor 1 (VEGFR1) in complex with N-(4-Chlorophenyl)-2-((pyridin-4-ylmethyl)amino)benzamide (8ST), for which the binding energy is known from in vitro experiments. In this study, our computed binding energy well agreed with the experimental value. Knowing the accuracy of this hSMD method, we applied it to the AQP5-lipid-bilayer system to answer an outstanding question relevant to AQP5's physiological function: Will the PS6, a lipid having a single long hydrocarbon tail that was found in the central pore of the AQP5 tetramer crystal, actually bind to and inhibit AQP5's central pore under near-physiological conditions, namely, when AQP5 tetramer is embedded in a lipid bilayer? We found, in silico, using the CHARMM 36 force field, that binding PS6 to AQP5 was a factor of 3 million weaker than "binding" it in the lipid bilayer. This suggests that AQP5's central pore will not be inhibited by PS6 or a similar lipid in a physiological environment.
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Affiliation(s)
- Liao Y Chen
- Department of Physics, University of Texas at San Antonio , One UTSA Circle, San Antonio, Texas , USA
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9
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Lin CI, Merley A, Sciuto TE, Li D, Dvorak AM, Melero-Martin JM, Dvorak HF, Jaminet SCS. TM4SF1: a new vascular therapeutic target in cancer. Angiogenesis 2014; 17:897-907. [PMID: 24986520 DOI: 10.1007/s10456-014-9437-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/23/2014] [Indexed: 12/31/2022]
Abstract
Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane glycoprotein that regulates cell motility and proliferation. TM4SF1 is an attractive cancer target because of its high expression in both tumor cells and on the vascular endothelial cells lining tumor blood vessels. We generated mouse monoclonal antibodies against human TM4SF1 in order to evaluate their therapeutic potential; 13 of the antibodies we generated reacted with extracellular loop-2 (EL2), TM4SF1's larger extracellular, lumen-facing domain. However, none of these antibodies reacted with mouse TM4SF1, likely because the EL2 of mouse TM4SF1 differs significantly from that of its human counterpart. Therefore, to test our antibodies in vivo, we employed an established model of engineered human vessels in which human endothelial colony-forming cells (ECFC) and human mesenchymal stem cells (MSC) are incorporated into Matrigel plugs that are implanted subcutaneously in immunodeficient nude mice. We modified the original protocol by (1) preculturing human ECFC on laminin, fibronectin, and collagen-coated plates, and (2) increasing the ECFC/MSC ratio. These modifications significantly increased the human vascular network in Matrigel implants. Two injections of one of our anti-TM4SF1 EL2 monoclonal antibodies, 8G4, effectively eliminated the human vascular component present in these plugs; they also abrogated human PC3 prostate cancer cells that were incorporated into the ECFC/MSC Matrigel mix. Together, these studies provide a mouse model for assessing tumor xenografts that are supplied by a human vascular network and demonstrate that anti-TM4SF1 antibodies such as 8G4 hold promise for cancer therapy.
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Affiliation(s)
- Chi-Iou Lin
- The Center for Vascular Biology Research, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, RN-280D, Boston, MA, 02215, USA
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10
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Yu D, Zhang C, Wang H, Qin P. Characterization of the weak calcium binding of trimeric globular adiponectin. Cell Biochem Funct 2012; 31:338-43. [PMID: 23023478 DOI: 10.1002/cbf.2906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 08/06/2012] [Accepted: 09/07/2012] [Indexed: 01/20/2023]
Abstract
Adiponectin is secreted from adipose tissue and functions as a protein hormone in regulating glucose metabolism and fatty acid catabolism. Adiponectin plays an important role as a novel risk factor and potential diagnostic and prognostic biomarker in cancer. Crystal structures of globular adiponectin have been resolved with three calcium-binding sites on the top of its central tunnel. However, the calcium-binding property of adiponectin remains elusive. Mouse globular adiponectin was cloned into pET11a and expressed in Escherichia coli. The folding of adiponectin was indicated by the spread of resonances in HSQC spectrum. Luminescence resonance energy transfer was used to obtain the binding constant (K(d)) of Tb(3+) and the inhibitor constant (K(i)) of Ca(2+) for globular adiponectin. The obtained calcium-binding affinity to adiponectin is relatively low (~2 mM), which indicates that the high concentration of adiponectin in circulating system may function as calcium storage bank and buffer the free calcium concentration.
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Affiliation(s)
- Dongmei Yu
- Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA
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11
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Chai SC, Ye QZ. Analysis of the stoichiometric metal activation of methionine aminopeptidase. BMC BIOCHEMISTRY 2009; 10:32. [PMID: 20017927 PMCID: PMC2807865 DOI: 10.1186/1471-2091-10-32] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 12/17/2009] [Indexed: 11/10/2022]
Abstract
Background Methionine aminopeptidase (MetAP) is a ubiquitous enzyme required for cell survival and an attractive target for antibacterial and anticancer drug development. The number of a divalent metal required for catalysis is under intense debate. E. coli MetAP was shown to be fully active with one equivalent of metal by graphical analysis, but it was inferred to require at least two metals by a Hill equation model. Herein, we report a mathematical model and detailed analysis of the stoichiometric activation of MetAP by metal cofactors. Results Because of diverging results with significant implications in drug discovery, the experimental titration curve for Co2+ activating MetAP was analyzed by fitting with a multiple independent binding sites (MIBS) model, and the quality of the fitting was compared to that of the Hill equation. The fitting by the MIBS model was clearly superior and indicated that complete activity is observed at a one metal to one protein ratio. The shape of the titration curve was also examined for activation of metalloenzymes in general by one or two metals. Conclusions Considering different scenarios of MetAP activation by one or two metal ions, it is concluded that E. coli MetAP is fully active as a monometalated enzyme. Our approach can be of value in proper determination of the number of cations needed for catalysis by metalloenzymes.
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Affiliation(s)
- Sergio C Chai
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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12
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Chai SC, Lu JP, Ye QZ. Determination of binding affinity of metal cofactor to the active site of methionine aminopeptidase based on quantitation of functional enzyme. Anal Biochem 2009; 395:263-4. [PMID: 19712663 DOI: 10.1016/j.ab.2009.07.054] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 06/23/2009] [Accepted: 07/17/2009] [Indexed: 10/20/2022]
Abstract
Determination of metal affinity to the active site of metalloenzymes constitutes an integral part in the understanding of enzyme catalysis and regulation. Nonlinear curve fitting of metal titration curves using the multiple independent binding sites (MIBS) model was adapted to determine K(D) values based on functional enzyme concentrations. This approach provides a more accurate evaluation of K(D) compared with existing methods that are based on total protein concentrations. We applied this concept to methionine aminopeptidase from Mycobacterium tuberculosis and showed that it is a monometalated enzyme with a K(D) of 0.13 microM for Co(2+).
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Affiliation(s)
- Sergio C Chai
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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13
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Tabrizi MA, Bornstein GG, Klakamp SL, Drake A, Knight R, Roskos L. Translational strategies for development of monoclonal antibodies from discovery to the clinic. Drug Discov Today 2009; 14:298-305. [PMID: 19152840 DOI: 10.1016/j.drudis.2008.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 12/08/2008] [Accepted: 12/09/2008] [Indexed: 01/24/2023]
Abstract
Successful strategies for the development of monoclonal antibodies require integration of knowledge with respect to target antigen properties, antibody design criteria such as affinity, isotype selection, Fc domain engineering, PK/PD properties and antibody cross-reactivity across species from the early stages of antibody development. Biophysical measurements are one of the critical components necessary for the design of effective translational strategies for lead selection and evaluation of relevant animal species for preclinical safety and efficacy studies. Incorporation of effective translational strategies from the early stages of the antibody development process is a necessity; when considered it not only reduces development time and cost, but also fosters implementation of rational decision-making throughout all phases of antibody development.
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14
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Rathanaswami P, Babcook J, Gallo M. High-affinity binding measurements of antibodies to cell-surface-expressed antigens. Anal Biochem 2007; 373:52-60. [PMID: 17910940 DOI: 10.1016/j.ab.2007.08.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2007] [Revised: 08/10/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
A simple method that allows affinity measurements of antibodies to integral membrane proteins is described. Kinetic Exclusion Assay was used to determine the concentration of free antibody that remains in solution after equilibrium has been established between the antibody and the cell-surface-expressed antigen, from which the equilibrium dissociation constant (Kd) was determined. It eliminates the requirement for soluble antigen and modifications such as radio-labeling or fluorescent labeling of the antibody. For one of the cell-surface-expressed antigens, it was determined that the affinity of the antibody to the cell-surface-expressed antigen was similar to that of the purified, soluble form of the antigen. In addition to the simplicity of the approach, the method provides a true measure of the affinity/avidity of the antibody to the native form of cell-surface-expressed targets, including antigens that cannot be produced in soluble forms, and to unknown cell surface antigens.
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