Key result
Alkali ions alter the molecular structure of myosin, with KCl restricting the rotational freedom of the spin label more than other salts and Ca2+ quenching fluorescence most effectively in KCl.
Alkali ions, particularly KCl, and Ca2+ significantly alter the molecular conformation of myosin in vitro.
Should not inform clinical ion use; leaves open myosin conformational effects in cardiac muscle.
We have used two probes to study the effects of alkali ions on the conformation of myosin. One was paramagnetic, the “spin label” N ‐(1‐oxyl‐2,2,6,6‐tetramethyl‐4‐piperidinyl)‐maleimide, which binds primarily to SH groups; and the other was fluorescent, l‐anilino‐8‐naphthalenesulfonate, which binds to an apolar niche. The bonding of the spin label to myosin was carried out in 0.6 M LiCl, 0.6 M NaCl, or 0.6 M KCl, and the resulting labeled myosin was studied in the same medium in which the myosin was labeled as well as in other alkali chlorides. The electron paramagnetic resonance spectra of the spin label showed that the structure of myosin in the vicinity of the labeled groups differed in the various salts. The protein surface in the region of the labeled groups restricted the rotational freedom of the spin label more in KCl than in any of the other salts. Although ions are known to influence the properties of myosin, our results show that these ions also effect the molecular structure. The fluorescence of l‐anilino‐8‐naphthalenesulfonate, noncovalently attached to myosin in the presence of alkali chlorides, decreased progressively with increasing size of the cations, again showing the protein structure near the probe attachment to be a function of the cation, in the solvent. Ca 2+ quenched the fluorescence of the bound probe, indicating an interaction between Ca 2+ and the myosin molecule. The effect of Ca 2+ on the fluorescence was greatest in KCl.
No takes yet. Share an insight, caveat, or question.
Cheung et al. (1971) studied Myosin conformation. Alkali ions (LiCl, NaCl, KCl) vs. Different alkali chlorides was evaluated on Myosin conformation (EPR spectra and fluorescence). Alkali ions alter the molecular structure of myosin, with KCl restricting the rotational freedom of the spin label more than other salts and Ca2+ quenching fluorescence most effectively in KCl.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: