1H-NMR Studies of Calmodulin: The Modifying Effect of W-7 (N-(6-Aminohexyl)-5-Chloro-1-Naphthalenesulfonamide) on the Calcium-Induced Conformational Changes of Calmodulin

Akiyama, Kayo; Sutoo, Den'etsu

doi:10.1254/jjp.48.157

Cited by 8 publications

(4 citation statements)

References 28 publications

(10 reference statements)

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“…The methionine methyl peaks are labelled by Arabic numerals. These numbers cor respond to those in our previous reports(12,15). Me t+: various divalent cations.…”

supporting

confidence: 92%

“…It was thought, therefore, that an interface for the binding of calmodulin to the regulatory sites on target enzymes exists in the vicinity of the high-field corresponding residues and that they play an important role in many intracel lular calcium-dependent functions. The loca tions of the interface on calmodulin for target enzymes has been suggested in our other serial report (15). It shows that they exist in the hydrophobic amino acid residues of Cat+ binding sites II, III and IV (numbered from N-terminus).…”

Section: Discussionmentioning

confidence: 58%

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1H-NMR studies of calmodulin: The character of the calcium binding sites.

et al. 1989

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The effects of various divalent cations on the Cat'-binding sites of calmodulin were observed by 400 MHz 1 H-NMR. The first and second Ca ions bound to sites III and IV (stage I), while the third and fourth bound to sites I and II (stage II). Zn2+, Hg2+ and Mn2+ bound to the first and third Cat'-binding sites, but not to the second and fourth. Zn2+, Hg2+ or Mn2+ coula bind to the first Ca2{ binding site by themselves and could bind to the third site only after the conformational change which occurs when two Ca2+ ions bind to first and second sites. Although Mg2+ did not bind to the first, second or fourth Ca2+-binding sites , it did bind to the third site. These results suggest that the order of Ca2+-binding and the order of affinity of the binding sites are not parallel; the first and third Ca2+-binding sites have high Ca2+-affinity, with the third being highest, whereas the second and fourth sites are of lower affinity. Also, we suggest in this study that the first and second sites are exposed on the surface of the protein, while the third and fourth ones are buried in the interior; the latter are exposed by the conformational change ac companying the binding of calcium to the first and second sites. Furthermore , the form of the interface by which calmodulin binds to target enzyme was altered slowly and continuously by the calcium-induced conformational change. The target enzyme was chosen and bound selectively to calmodulin among various enzymes by each interface form.

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“…The methionine methyl peaks are labelled by Arabic numerals. These numbers cor respond to those in our previous reports(12,15). Me t+: various divalent cations.…”

supporting

confidence: 92%

Section: Discussionmentioning

confidence: 58%

1H-NMR studies of calmodulin: The character of the calcium binding sites.

et al. 1989

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“…The inhibitory propensities of W 7 also suggest that those residues on CaM with which it interacts are also important in regulating its binding to target enzymes. This study confirms previous observations of the similarity of the effects of Ca2+ and Cd2+ on CaM (8)(9)(10), and of the effects of W-7 on the Cat+-saturated protein (22,23). In addition, we have shown that W-7 affects Cd2+-saturated CaM in a very similar fashion by a detailed comparison of the changes which it induces in the spectrum of each metal-bound form of the protein.…”

Section: Discussionsupporting

confidence: 90%

“…(15). Previous studies (22,23) by 1H-NMR of W-7 binding to Ca2+-bound CaM suggest that W-7 interacts with hydrophobic amino acid residues in the vicinity of the cal cium-binding sites of domains II, III and IV and influences those. The effects exerted by W-7 appear similar to those of trifluoperazine (a CaM antagonist with other pharmacologi cal properties), D600 (a calcium channel blocker and CaM antagonist) and oxmetidine (a histamine H2 antagonist), whence it may be inferred that they bind to similar regions of the protein.…”

Section: Discussionmentioning

confidence: 93%