Conformational changes in actin resulting from Ca2+/Mg2+ exchange as detected by proton NMR spectroscopy
- 1 January 1985
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 146 (1) , 5-8
- https://doi.org/10.1111/j.1432-1033.1985.tb08612.x
Abstract
Skeletal muscle actin can be maintained in a monomeric form in very low ionic strength solutions as well as in high concentrations (0.6 M) of MgCl2 or CaCl2, 400‐MHz 1H‐NMR spectra revealed characteristic changes which show that the conformation of actin alters by exchanging Ca2+ for Mg2+ in the single high‐affinity cation binding site. When all low‐affinity cation binding sites are filled (in the presence of high concentration of Ca2+ or Mg2+), the spectra show that actin conformation differs from that in low‐ionic‐strength buffer. A comparison of actin in 0.6 M CaCl2 and 0.6 M MgCl2 revealed that the environment of only a small number of protons is affected by the exchange. A new proposal for the essential steps involved in actin polymerization is presented.This publication has 26 references indexed in Scilit:
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