Path: utzoo!attcan!uunet!mailrus!accuvax.nwu.edu!anaxagoras!ils.nwu.edu!barger
From: barger@ils.nwu.edu (Jorn Barger)
Newsgroups: sci.bio
Subject: Visualizing muscle contraction
Message-ID: <1912@anaxagoras.ils.nwu.edu>
Date: 26 Sep 90 13:17:34 GMT
Sender: news@anaxagoras.ils.nwu.edu
Organization: Institute for the Learning Sciences
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All the references I've checked always visualize muscle contraction in 
terms of ATP causing _conformation changes_ in cross-bridges that ratchet 
or somehow drag the myosin along the actin, rather like the guy in 
cartoons dragging himself across the desert sands...

But if you acknowledge that most of the energy released by breaking a 
phosphate off ATP is released as kinetic repulsion, shouldn't there be a 
Newtonian recoil?  Wouldn't that make a much neater mechanism, ATP's 
firing simultaneously and contraction looking like big anti-aircraft guns 
recoiling?  Jet powered?

Which visualization is more consistent with measurements?  One big 
difference seems to me to be that the crossbridges idea implies that there 
will be an adhesive force _holding_ the muscle in its contracted state...

How could you test this?  Will ATP fire when bound to myosin in the 
absence of actin?  Could you align a lot of myosin and detect the 
resulting pressure-pulse?


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(when it's quiet/ i can hear the dolphins sing)
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