Conformation, pH-induced conformational changes, and thermal unfolding of anti-p24 (HIV-1) monoclonal antibody CB4-1 and its Fab and Fc fragments.

Important note: Information in this article was accurate in 1999. The state of the art may have changed since the publication date.

Conformation, pH-induced conformational changes, and thermal unfolding of anti-p24 (HIV-1) monoclonal antibody CB4-1 and its Fab and Fc fragments.

Biochim Biophys Acta. 1999 Apr 12;1431(1):120-31. Unique Identifier : AIDSLINE MED/99227077
Welfle K; Misselwitz R; Hausdorf G; Hohne W; Welfle H; Max-Delbruck-Centrum fur Molekulare Medizin,; Robert-Rossle-Str. 10, D-13092, Berlin, Germany.; welfle@mdc-berlin.de

Abstract: Conformation, acid-induced conformational changes and stability of the murine monoclonal antibody CB4-1 directed against the human immunodeficiency virus type 1 capsid protein p24, and its Fab and Fc fragments, were analysed by circular dichroism (CD), fluorescence, and differential scanning calorimetry (DSC) measurements. CD spectra show the characteristics expected for beta-proteins. Lowering the pH to 3.5 reduces the stability, but does not change the conformation. Between pH 3.5 and 2.0 conformational changes and the formation of new structures are indicated. Deconvolution of the bimodal DSC curves of CB4-1 reveals five 'two-state' transitions at pH 7.5. At pH 5 and below, only four transitions are found. Half transition temperatures Tm and molar enthalpy changes DeltaHm gradually decrease at pH 4 and 3.4. At pH 2.1, two low-temperature (Tm=36.9 and 44.1 degrees C) and two high-temperature (Tm=74.6 and 76.8 degrees C) transitions are identified. The Fab and Fc fragments behave similarly. Deconvolution of their monophasic DSC curves yields two 'two-state' transitions for each fragment. Tm and DeltaHm values gradually decrease at pH 4.0 and 3.4; and at pH 2.1 and 2.8 for Fab and Fc, respectively, one of the transitions is found at high temperature (Tm=67.2 and 75.9 degrees C for Fab and Fc, respectively).

Keywords: JOURNAL ARTICLE Antibodies, Monoclonal/*CHEMISTRY Calorimetry, Differential Scanning Circular Dichroism *Heat Hydrogen-Ion Concentration HIV Core Protein p24/*IMMUNOLOGY *HIV-1 IgG/CHEMISTRY Immunoglobulins, Fab/CHEMISTRY Immunoglobulins, Fc/CHEMISTRY Protein Conformation *Protein Folding Spectrometry, Fluorescence Support, Non-U.S. Gov't
990830
A9980950

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