2ZKH

Human thrombopoietin neutralizing antibody TN1 FAB

Summary for 2ZKH

• Entry DOI: 10.2210/pdb2zkh/pdb
• Descriptor: Monoclonal TN1 FAB light chain, Monoclonal TN1 FAB heavy chain (3 entities in total)
• Functional Keywords: thrombopoietin, fab fragment(antibody), immune system
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 46727.02

Authors

Arai, S.,Tamada, T.,Honjo, E.,Maeda, Y.,Kuroki, R. (deposition date: 2008-03-21, release date: 2009-03-24, Last modification date: 2024-10-30)

Primary citation

Arai, S.,Shibazaki, C.,Adachi, M.,Honjo, E.,Tamada, T.,Maeda, Y.,Tahara, T.,Kato, T.,Miyazaki, H.,Blaber, M.,Kuroki, R.
An insight into the thermodynamic characteristics of human thrombopoietin complexation with TN1 antibody.
Protein Sci., 25:1786-1796, 2016

PubMed Abstract: Human thrombopoietin (hTPO) primarily stimulates megakaryocytopoiesis and platelet production and is neutralized by the mouse TN1 antibody. The thermodynamic characteristics of TN1 antibody-hTPO complexation were analyzed by isothermal titration calorimetry (ITC) using an antigen-binding fragment (Fab) derived from the TN1 antibody (TN1-Fab). To clarify the mechanism by which hTPO is recognized by TN1-Fab the conformation of free TN1-Fab was determined to a resolution of 2.0 Å using X-ray crystallography and compared with the hTPO-bound form of TN1-Fab determined by a previous study. This structural comparison revealed that the conformation of TN1-Fab does not substantially change after hTPO binding and a set of 15 water molecules is released from the antigen-binding site (paratope) of TN1-Fab upon hTPO complexation. Interestingly, the heat capacity change (ΔCp) measured by ITC (-1.52 ± 0.05 kJ mol(-1)  K(-1) ) differed significantly from calculations based upon the X-ray structure data of the hTPO-bound and unbound forms of TN1-Fab (-1.02 ∼ 0.25 kJ mol(-1)  K(-1) ) suggesting that hTPO undergoes an induced-fit conformational change combined with significant desolvation upon TN1-Fab binding. The results shed light on the structural biology associated with neutralizing antibody recognition.

PubMed: 27419667
DOI: 10.1002/pro.2985

Experimental method

X-RAY DIFFRACTION (2.04 Å)