Interaction of Biotin with Streptavidin

• DOI: 10.1074/jbc.272.17.11288
• Publication Date: 2002-07-26T10:49:13Z
• Authors: Martín González; Luis A. Bagatolli; Izaskun Echabe; Jose L.R. Arrondo; Carlos E. Argaraña; Charles R. Cantor; Gerardo D. Fidelio
• Keywords: Streptavidin

The effect of biotin binding on streptavidin (STV) structure and stability was studied using differential scanning calorimetry, Fourier transform infrared spectroscopy (FT-IR), fluorescence spectroscopy. Biotin increases the midpoint temperature Tm, thermally induced denaturation STV from 75 degrees C in unliganded protein to 112 at full ligand saturation. cooperativity unfolding changes substantially presence biotin. Unliganded monomer has least one domain that unfolds independently. dimer bound undergoes a single coupled process. Simulations thermograms take into account only thermodynamic effects with Ka approximately 10(15) reproduce behavior observed, but estimated values Tm are 15-20 lower than those experimentally determined. This increased is attributed an enhanced thermal STV. increment as consequence stronger intersubunit association structural order upon binding. FT-IR data reveal unordered found disappears under fully saturating conditions. provide rationale for previous suggestions induces increase tightness (structural cooperativity) leading, turn, higher thermostability.