A comparative CD and fluorescence study of a series of model calcium-binding peptides.
Lanthanide-saturated peptides analogous to calcium-binding loops of EF-hand proteins can be used to stabilize the alpha-helical structure of peptide or protein segments attached to their C-termini. To study conformational properties of such loop-containing hybrids it is necessary to produce them in bacteria. In peptides obtained in this way the helix will be destabilized by the negatively charged C-terminal alpha-carboxyl groups. We propose to block them by the homoserine lactone. The results presented in this paper indicate that the presence of the lactone even at the C-terminus of the loop does not have any negative effect on the loop helix-nucleation ability. On the other hand, the presence of the alpha-NH3+ at the loop N-terminus leads to a drop of metal-binding constant and loss of the rigid structure of the alpha-helical segment of the loop. The alpha-amino group separated by one glycine residue from the loop N-terminus should also be avoided because it perturbs the conformation of the N-terminal part of the loop and may reduce the loop affinity to lanthanide ions.
Goch
G
G
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa.
Kozłowska
H
H
Wójtowicz
A
A
Bierzyński
A
A
D000595:Amino Acid Sequence; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D008956:Models, Chemical; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence
D002135:Calcium-Binding Proteins