| Autor: |
Squire, J. M., AL-Khayat, H. A., Harford, J. J., Hudson, L., Irving, T., Knupp, C., Reedy, M. K. |
| Předmět: |
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| Zdroj: |
IEE Proceedings -- Nanobiotechnology; Dec2003, Vol. 150 Issue 3, p103-110, 8p, 2 Color Photographs, 3 Diagrams |
| Abstrakt: |
New results on myosin head organization using analysis of low-angle X-ray diffraction patterns from relaxed insect flight muscle (IFM)from a giant waterbug, building on previous studies of myosin filaments in bony fish skeletal muscle (BFM), show that the information content of such low-angle diffraction patterns is very high despite the 'crystallographically low' resolution limit (65 A ) of the spacings of the Bragg diffraction peaks being used. This high information content and high structural sensitivity arises because: (i) the atomic structures of the domains of the myosin head are known from protein crystallography+ADs- and (ii)myosin head action appears to consist mainly of pivoting between domains which themselves stay rather constant in structure; thus (iii)the intensity distribution among diffraction peaks in even the low resolution diffraction pattern s highly determined by the high-resolution distribution of atomically modelled domain mass. A single model was selected among 5000+ computer-generated variations as giving the best fit for the 65 reflections recorded within the selected resolution limit of 65 A. Clear evidence for a change in shape of the insect flight muscle myosin motor between the resting (probably like the prepowerstroke) state and the rigor state (considered to mimic the end-of-powerstroke conformation) has been obtained. This illustrates the power of the low-angle X-ray diffraction method. The implications of these new results about myosin motor action during muscle contraction are discussed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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