Thermodynamic basis for antibody binding to Z-DNA: Comparison of a monoclonal antibody and its recombinant derivatives

• Published in: Biochimica et biophysica acta Vol. 1726; no. 3; pp. 293 - 301
• Main Authors: Vaz de Andrade, Edmar, Freitas, Sonia Maria, Ventura, Manuel Mateus, Maranhão, Andréa Queiroz, Brigido, Marcelo Macedo
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 30.11.2005
• Subjects: Anti-DNA; Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - genetics; Antibodies, Monoclonal - immunology; Antibody Affinity; Binding, Competitive; DNA, Z-Form - immunology; Enthalpy–entropy compensation; Humans; Pichia pastoris; Protein engineering; Recombinant antibody; Recombinant Proteins - chemistry; Recombinant Proteins - immunology; Spectrometry, Fluorescence; Thermodynamics; Protein engineering; Enthalpy–entropy compensation; Pichia pastoris; Anti-DNA; Recombinant antibody
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2005.08.013

Antibody engineering represents a promising area in biotechnology. Recombinant antibodies can be easily manipulated generating new ligand and effector activities that can be used as prototype magic bullets. On the other hand, an extensive knowledge of recombinant antibody binding and stability features are essential for an efficient substitution. In this study, we compared the stability and protein binding properties of two recombinant antibody fragments with their parental monoclonal antibody. The recombinant fragments were a monomeric scFv and a dimeric one, harboring human IgG1 CH2–CH3 domains. We have used fluorescence titration quenching to determine the thermodynamics of the interaction between an anti-Z-DNA monoclonal antibody and its recombinant antibody fragments with Z-DNA. All the antibody fragments seemed to bind DNA similarly, in peculiar two-affinity states. Enthalpy–entropy compensation was observed for both affinity states, but a marked entropy difference was observed for the monomeric scFv antibody fragment, mainly for the high affinity binding. In addition, we compared the stability of the dimeric antibody fragment and found differences favoring the monoclonal antibody. These differences seem to derive from the heterologous expression system used.