Flexibility of the alpha-spectrin N-terminus by EPR and fluorescence polarization.
The structure and flexibility of the biologically important alpha-spectrin amino terminal region was examined by the use of fluorescence and EPR spectroscopy. The region studied has been previously demonstrated to be essential for the alpha-spectrin:beta-spectrin association of the tetramerization site. Appropriate spectroscopic probe moieties were coupled to this region in a recombinant fragment of human erythroid alpha-spectrin. There was good agreement between the EPR and fluorescence techniques in most of this region. Mobility determinations indicated that a portion of the region was relatively immobilized. This is significant, since although predictive methods have indicated that this region should be alpha-helical, previous experimental evidence obtained on smaller synthetic peptides had indicated that this region was disordered. Observed rigidity appears to be incompatible with such a disordered state, and has important ramifications for the flexibility of this molecule that is so integral to its role in stabilizing erythrocyte membranes.
Cherry
L
L
Department of Chemistry, Loyola University of Chicago, Chicago, Illinois 60626, USA.
Fung
L W
LW
Menhart
N
N
D020816:Amino Acid Motifs; D004578:Electron Spin Resonance Spectroscopy; D005454:Fluorescence Polarization; D009038:Motion; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics; D012399:Rotation; D013049:Spectrin / Q000737:chemistry* / Q000235:genetics; D013113:Spin Labels
D010446:Peptide Fragments; D011994:Recombinant Proteins; D013113:Spin Labels; D013049:Spectrin