Abstract
We have used EPR spectroscopy to study the rotational motion and orientation of tropomyosin labeled with maleimide spin-label, in skeletal muscle fibers. Fibers depleted of intrinsic myosin, troponin, and tropomyosin were reconstituted with labeled tropomyosin. The 3-7 ns mobility of the labeled domains was only slightly (2-fold) inhibited by reconstitution into fibers. No motional changes were observed on addition of troponin, irrespective of the presence of Ca2+; however, the binding of extrinsic myosin heads increased the rate of domain motion to that observed in solution. Orientational studies demonstrate a broad angular distribution of the labeled domain of tropomyosin, with respect to the fiber axis. Troponin reduces the orientational disorder, while the binding of Ca2+ to troponin partially reverses this ordering effect. Myosin S1 has no effect on the orientational distribution of tropomyosin. Overall, the observed changes are very small, implying a loose association of the probed domain of tropomyosin with the thin filament.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3614-3620 |
| Number of pages | 7 |
| Journal | Biochemistry |
| Volume | 34 |
| Issue number | 11 |
| DOIs | |
| State | Published - 1995 |
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ASJC Scopus subject areas
- Biochemistry
- Medicine(all)
Cite this
The tropomyosin domain is flexible and disordered in reconstituted thin filaments. / Szczesna-Cordary, Danuta; Fajer, P. G.
In: Biochemistry, Vol. 34, No. 11, 1995, p. 3614-3620.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The tropomyosin domain is flexible and disordered in reconstituted thin filaments
AU - Szczesna-Cordary, Danuta
AU - Fajer, P. G.
PY - 1995
Y1 - 1995
N2 - We have used EPR spectroscopy to study the rotational motion and orientation of tropomyosin labeled with maleimide spin-label, in skeletal muscle fibers. Fibers depleted of intrinsic myosin, troponin, and tropomyosin were reconstituted with labeled tropomyosin. The 3-7 ns mobility of the labeled domains was only slightly (2-fold) inhibited by reconstitution into fibers. No motional changes were observed on addition of troponin, irrespective of the presence of Ca2+; however, the binding of extrinsic myosin heads increased the rate of domain motion to that observed in solution. Orientational studies demonstrate a broad angular distribution of the labeled domain of tropomyosin, with respect to the fiber axis. Troponin reduces the orientational disorder, while the binding of Ca2+ to troponin partially reverses this ordering effect. Myosin S1 has no effect on the orientational distribution of tropomyosin. Overall, the observed changes are very small, implying a loose association of the probed domain of tropomyosin with the thin filament.
AB - We have used EPR spectroscopy to study the rotational motion and orientation of tropomyosin labeled with maleimide spin-label, in skeletal muscle fibers. Fibers depleted of intrinsic myosin, troponin, and tropomyosin were reconstituted with labeled tropomyosin. The 3-7 ns mobility of the labeled domains was only slightly (2-fold) inhibited by reconstitution into fibers. No motional changes were observed on addition of troponin, irrespective of the presence of Ca2+; however, the binding of extrinsic myosin heads increased the rate of domain motion to that observed in solution. Orientational studies demonstrate a broad angular distribution of the labeled domain of tropomyosin, with respect to the fiber axis. Troponin reduces the orientational disorder, while the binding of Ca2+ to troponin partially reverses this ordering effect. Myosin S1 has no effect on the orientational distribution of tropomyosin. Overall, the observed changes are very small, implying a loose association of the probed domain of tropomyosin with the thin filament.
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U2 - 10.1021/bi00011a016
DO - 10.1021/bi00011a016
M3 - Article
VL - 34
SP - 3614
EP - 3620
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 11
ER -