Physical Properties of a Single-Motif Erythrocyte Spectrin Peptide: A Highly Stable Independently Folding Unit
- 1 April 1997
- journal article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 36 (13), 3991-3997
- https://doi.org/10.1021/bi962412j
Abstract
Spectrin is a long flexible rod-like actin cross-linking protein mostly comprised of many tandem homologous 106-residue motifs. In this study, the conformational stability and physical properties of a single homologous motif peptide, α1, were evaluated and compared to intact spectrin monomers and αβ heterodimers. It is interesting that while spectrin dimers elongate by about 3-fold in low ionic strength buffers relative to their size in physiological buffers, the single-motif peptide does not show significant changes in secondary structure in 10 mM phosphate buffer compared with isotonic buffer. This single-motif peptide is monomeric in physiological buffer as demonstrated by equilibrium sedimentation studies, and its hydrodynamic radius determined by gel filtration and dynamic light scattering of about 2.2 nm is consistent with an elongated rod-like shape. Unfolding of the single-motif peptide in urea solutions was similar to unfolding of intact heterodimers. Differential scanning calorimetry analyses showed that this single motif undergoes a reversible two-state transition with a Tm of 53 °C and an enthalpy of 65 kcal/mol in physiological buffer. Thermal stability was unaffected by ionic strength changes, but was decreased below physiological pH. These data show that this 13 kDa spectrin motif is a monomeric, highly stable, triple-helical, independently folding protein building block with physical characteristics that define many of the structural properties of the 526 kDa spectrin heterodimer. In contrast, interactions between adjacent motifs are probably responsible for spectrin's molecular flexibility and elasticity.Keywords
This publication has 9 references indexed in Scilit:
- Mapping the Human Erythrocyte β-Spectrin Dimer Initiation Site Using Recombinant Peptides and Correlation of Its Phasing with the α-Actinin Dimer SitePublished by Elsevier ,1996
- Conformation and Phasing of Dystrophin Structural RepeatsJournal of Molecular Biology, 1994
- Conformation and elasticity of the isolated red blood cell membrane skeletonBiophysical Journal, 1992
- Ankyrin binds to the 15th repetitive unit of erythroid and nonerythroid beta-spectrin.The Journal of cell biology, 1991
- Elasticity of the human red cell membrane skeleton. Effects of temperature and denaturantsBiophysical Journal, 1989
- An electro-optic study of human erythrocyte spectrin dimersBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1984
- Role of the reticulum in the stability and shape of the isolated human erythrocyte membraneThe Journal of cell biology, 1982
- The molecular structure of human erythrocyte spectrinJournal of Molecular Biology, 1979
- Human spectrin. II. An electro-optic studyBiochimica et Biophysica Acta (BBA) - Protein Structure, 1978