Chlamydomonas 13C-centrin and Melittin interaction

SOSA LILIANA DEL VALLE; PASTRANA RIOS BELINDA

Boston, Massachusetts

Simposio; Nineteenth Symposium of the Protein Society; 2005

Chlamydomonas centrin is an acidic, low molecular weight protein that belongs to the EF-hand superfamily of calcium binding proteins.  In the presence of calcium, centrin forms a complex with mellitin (MLT) which is an amphiphilic peptide from bee venom. Calcium binding proteins in general have an unusually high thermal denaturation temperature, at times a conformational transition (pre-transition) is observed prior to melting. Transition temperature upon complex formation between Chlamydomonas 13C-labeled centrin and a 26-residue peptide, mellitin, were studied in aqueous D2O solution as a function of temperature using Fourier transform-infrared (FT-IR) spectroscopy and two-dimensional correlation analysis (2DCOS). The use of isotope labeling can applied in a protein and thus probes the changes that occur in presence the peptide. Spectral features studied in the spectral region amide I (1720-1550 cm-1) were characteristic of the protein complex. Therefore, the relative thermal stability for these proteins was established.