scholarly journals Thermal and Chemical Unfolding of a recombinant monoclonal IgG1 antibody: Application of the Multi-State Zimm-Bragg Theory

2019 ◽  
Author(s):  
P. Garidel ◽  
A. Eiperle ◽  
M. Blech ◽  
J. Seelig
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Differential Scanning Calorimetry ◽  
Amino Acid ◽  
Quantitative Description ◽  
Thermal Unfolding ◽  
Scanning Calorimetry ◽  
Main Transition ◽  
Binding Enthalpy ◽  
Dsc Thermograms

AbstractThe thermal unfolding of a recombinant monoclonal antibody IgG1 (mAb) was measured with differential scanning calorimetry (DSC). The DSC thermograms reveal a pre-transition at 72°C with an unfolding enthalpy of ΔHcal ∼ 200-300 kcal/mol and a main transition at 85 °C with an enthalpy of ∼900 - 1000 kcal/mol. In contrast to single-domain molecules, mAb unfolding is a complex reaction that is analysed with the multi-state Zimm-Bragg theory. For the investigated mAb, unfolding is characterised by a cooperativity parameter σ ∼10−4 and a Gibbs free energy of unfolding of gnu ∼100 cal/mol per amino acid. The enthalpy of unfolding provides the number of amino acid residues v participating in the unfolding reaction. On average, v∼220±50 amino acids are involved in the pre-transition and v∼850±30 in the main transition, accounting for ∼90% of all amino acids. Thermal unfolding was further studied in the presence of guanidineHCl. The chemical denaturant reduces the unfolding enthalpy ΔHcal and lowers the midpoint temperature T0. Both parameters depend linearly on the concentration of denaturant. The guanidineHCl concentrations needed to unfold mAb at 25 °C are predicted to be 2-3 M for the pre-transition and 5-7 M for the main transition, varying with pH. GuanidineHCl binds to mAb with an exothermic binding enthalpy, which partially compensates the endothermic mAb unfolding enthalpy. The number of guanidineHCL molecules bound upon unfolding is deduced from the DSC thermograms. The bound guanidineHCl-to-unfolded amino acid ratio is 0.79 for the pre-transition and 0.55 for the main transition. The pre-transition binds more denaturant molecules and is more easily destabilised than the main transition.Overall, the current study shows the strength of the Zimm-Bragg model for the quantitative description of unfolding events of large, therapeutic proteins, such as a monoclonal antibody.Statement of significanceFirst quantitative thermodynamic study of an antibody with differential scanning calorimetry and analyzed with the multi-state Zimm-Bragg theory.

Dynamic Globularization of α-Phase in Ti6Al4V Alloy during Hot Compression

2014 ◽  
Vol 783-786 ◽  
pp. 584-590 ◽  
Author(s):  
Kalenda Mutombo ◽  
C. Siyasiya ◽  
W.E. Stumpf
Keyword(s):  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Strain Rate ◽  
Alpha Phase ◽  
Ti6al4v Alloy ◽  
Thermodynamic Calculations ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Α Phase ◽  
Dsc Thermograms

Ti6Al4V samples were isothermally compressed using a Gleeble(TM) 1500D thermo-mechanical simulator. Differential scanning calorimetry (DSC), microstructural analyses, and thermodynamic calculations were used to investigate the sequence of transformation of β into α or vice-versa and the presence of different phases in the compressed Ti6Al4V sample. Globular alpha phase was revealed in the isothermally compressed sample in addition to martensitic and lamellar α/β structures. The transition temperature range of β into α-phase was determined using the DSC thermograms and thermodynamic calculated diagrams. The fraction of α-phase globulized increased as the strain rate decreased from 0.01s-1 to 10-3s-1, and the spheroidization of the α-phase is only possible in a specific range of deformation temperatures.

SAXS Study of Selected Cationic Surfactant Influence on the DSPC-Based Model Phospholipid System

2007 ◽  
Vol 130 ◽  
pp. 257-262
Author(s):  
Maciej Kozak ◽  
Ludwik Domka ◽  
Stefan Jurga
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Phase Behaviour ◽  
Lamellar Phase ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Hydrocarbon Chains ◽  
Main Transition

The phase behaviour of lipid bilayer systems prepared with 1,2-distearoyl-sn-glycero-3- phosphocholine (DSPC) with dodecyldimethyl(benzyloxymethyl)ammonium chloride (BzMDDAC) (at concentrations 0.1, 1 and 5%) has been studied by small angle X-ray scattering and differential scanning calorimetry. The SAXS and DSC results of the hydrated 10% DSPC revealed one typical phase transition corresponding to melting of the hydrocarbon chains at 55 °C. In the system of 10% DSPC - 0.1 % BzMDDAC the main transition was somewhat shifted towards lower temperatures, while at 1% concentration of BzMDDAC in the mixture, the lamellar phase disappeared, as evidenced by SAXS and DSC. The increase in BzMDDAC concentration to 5% in the mixture with 10% DSPC resulted in formation of a new lamellar phase.

Thermophysical Study of Several α- and β-Amino Acid Derivatives by Differential Scanning Calorimetry (DSC)

2011 ◽  
Vol 56 (10) ◽  
pp. 3807-3812 ◽  
Author(s):  
María Victoria Roux ◽  
Rafael Notario ◽  
Marta Segura ◽  
Ramón Guzmán-Mejía ◽  
Eusebio Juaristi ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Amino Acid ◽  
Amino Acid Derivatives ◽  
Scanning Calorimetry

scholarly journals Association Between the Rat Homologue of CO-029, a Metastasis-associated Tetraspanin Molecule and Consumption Coagulopathy

1998 ◽  
Vol 141 (1) ◽  
pp. 267-280 ◽  
Author(s):  
Christoph Claas ◽  
Simone Seiter ◽  
Andreas Claas ◽  
Larissa Savelyeva ◽  
Manfred Schwab ◽  
...  
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Amino Acid ◽  
Functional Role ◽  
Human Tumor ◽  
Tumor Cell Line ◽  
Metastatic Potential ◽  
Massive Bleeding ◽  
Consumption Coagulopathy

Recently, we have described a panel of metastasis-associated antigens in the rat, i.e., of molecules expressed on metastasizing, but not on nonmetastasizing tumor lines. One of these molecules, recognized by the monoclonal antibody D6.1 and named accordingly D6.1A, was found to be abundantly expressed predominantly on mesenchyme-derived cells. The DNA of the antigen has been isolated and cloned. Surprisingly, the gene product proved to interfere strongly with coagulation. The 1.182-kb cDNA codes for a 235–amino acid long molecule with a 74.2% homology in the nucleotide and a 70% homology in the amino acid sequence to CO-029, a human tumor-associated molecule. According to the distribution of hydrophobic and hydrophilic amino acids, D6.1A belongs to the tetraspanin superfamily. Western blotting of D6.1A-positive metastasizing tumor lines revealed that the D6.1A, like many tetraspanin molecules, is linked to further membrane molecules, one of which could be identified as α6β1 integrin. Transfection of a low-metastasizing tumor cell line with D6.1A cDNA resulted in increased metastatic potential and provided a clue as to the functional role of D6.1A. We noted massive bleeding around the metastases and, possibly as a consequence, local infarctions predominantly in the mesenteric region and all signs of a consumption coagulopathy. By application of the D6.1 antibody the coagulopathy was counterregulated, though not prevented. It has been known for many years that tumor growth and progression is frequently accompanied by thrombotic disorders. Our data suggest that the phenomenon could well be associated with the expression of tetraspanin molecules.

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