Time table

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Linear Motors
Time table Hugh Huxley Introduction.
6 mins.

X-ray interference experiments
28 mins. on whole
muscles. Yale Goldman Structural dynamics of
individual 28 mins.
myosin molecules in real time.
Ken Holmes The structural
basis of the crossbridge 28 mins.
cycle.


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LINEAR MOTORS Linear motors are molecular
machines which can transform chemically stored
energy in ATP into directed force and linear
movement. How do myosin heads produce force
and linear movement in actin based systems?
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Relative sliding of arrays of actin and myosin
filaments produced by cross-bridges causes
muscle contraction
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37 nanometers
Actin Filament
Myosin V
Motor Domains
Calmodulins
Stalk
Cargo Binding Domain
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37 nanometers
Actin Filament
Myosin V
Motor Domains
Calmodulins
Stalk
Cargo Binding Domain
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The Key Problems we need to a) Show that the
structure of the myosin molecule could plausibly
undergo the large shape change required. b) Show
that such a cyclical structural change actually
takes place in a contracting muscle.
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X-ray crystallographic structure of myosin
sub-fragment one S1.
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X-ray interference experiments on whole muscles.
Hugh Huxley. Rosenstiel Center, Brandeis Univ.,
Waltham, Mass. U.S.A.
huxley_at_brandeis.edu
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The experiments do provide good evidence that the
lever arms tilt during the working stroke, and
that they and the catalytic domains move inwards
towards the centre of the A-band by the amounts
expected on the tilting lever arm model
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Somewhat unexpectedly, the attached heads in
isometric contraction are concentrated around the
beginning of the working stroke, rather than
being spread out fairly uniformly as envisaged in
some models. Presumably, ones that were attached
further into the stroke have detached and not
been replaced as the contraction became
isometric. So, what happens during steady
shortening?
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A.F.Huxley-Simmons quick release experiment,
showing very rapid initial tension recovery.
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