?The interaction of Chlamydomonas 13C-centrin with Melittin an anphiphilic peptide

SOSA LILIANA DEL VALLE; PASTRANA RIOS BELINDA

San Juan, Puerto Rico

Congreso; 2nd Colloquium in Protein Structure, Function and Dynamics,; 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).  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.  In addition Hydrogen deuterium exchange studies were also performed for the individual protein components and the binary mixture using attenuated total reflectance (ATR) FT-IR spectroscopy.