Structural changes in 13C-centrin and Melittin upon binding

SOSA LILIANA DEL VALLE; PASTRANA RIOS BELINDA

Mayagüez Puerto Rico

Congreso; Second Latin American and Caribbean Biotechnology Congress; 2004

Chlamydomonas centrin is an acidic, low molecular weight protein that belongs to the EF-hand superfamily of calcium binding proteins. It is an essential component of the centrosomal structures in a wide range of organisms. In the presence of calcium, centrin forms a complex with mellitin (MLT) which is an amphiphilic peptide from bee venom. Structural changes upon complex formation between Chlamydomonas 13C-labeled centrin and a 26-residue peptide, mellitin, were studied using H1-H2 exchange dynamics via a combined attenuated total reflectance (ATR) Fourier transform-infrared (FT-IR) spectroscopy and two-dimensional correlation analysis (2D-COS). This technique is useful in determining the secondary structure and the extent of H1-H2 exchange mechanism and kinetics. Spectral features studied in the spectral region 1800-1400 cm-1 were characteristic of the two proteins. The amide I´ band (1650 cm-1) contained MLT and the amide I*´ band (1600 cm-1) contains 13C-centrin, these bands are comprised of the C=O peptide band stretching mode. The amide II band comprised of side chains and the N-H deformation mode (1550 cm-1) and the amide II´  (1450 cm-1) band is comprised of the N-D deformation mode.  The results obtained will be discussed in terms of the individual protein components and the molecular nature of the interaction.