کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1931175 | 1050543 | 2011 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber](/preview/png/1931175.png)
Muscle contraction results from an attachment–detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release of hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.
Research highlights
► We succeeded in recording structural changes of hydrated myosin cross-bridges.
► We succeeded in position-marking the cross-bridges with site-directed antibodies.
► We recorded cross-bridge movement at different regions in individual cross-bridge.
► The movement was smallest at the cross-bridge-subfragment two boundary.
► The results provide evidence for the cross-bridge lever arm mechanism.
Journal: Biochemical and Biophysical Research Communications - Volume 405, Issue 4, 25 February 2011, Pages 651–656