Mammalian%20Muscle%20Properties

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Mammalian Muscle Properties
Madden et al. IEEE J. Oceanic Engr. 29 706, 2004
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Skeletal muscle features

• Muscle surpasses artificial actuators only in the
  fuel delivery
• Linear actuation
• Adapted for intermittent duty and stiffness
  (compliance) control
• Versatile force control recruitment stiffness
  modulation (w/o feedback)

Madden et al. IEEE J. Oceanic Engr. 29 706, 2004
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Hill model Force dependence on contraction
velocity
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Motor Specific Power Ergs/s-g Force (dynes) Velocity mm/s
Actin Polymerization mtubule polymerization 109 108 10-7 10-7 1 .02
Myosin II Kinesin Spasmoneme 108 107 109 10-6 10-7 10-3 4 1 80,000
Car Striated muscle Bacterial Flagella Limulus aroscome Eukaryote Flagella Mitotic spindle 106 106 106 104 102 10-6 10-5 100 Hz 10 2
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McKibben muscle
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McK muscles

• Steel braid wrapped around a rubber tube.
• Crimped at ends

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20N/g
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Testing
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Antagonistic pairs for smooth torque
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Friction in the mesh

• Filament on filament friction (no sliding
  relative to the tube)

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Properties of McK muscles

• 1. Fstatic CSA (pro2)
• 2. Fstatic P
• 3. Fstatic is independent of initial length
• 4. Fstatic max 1/ao
• 5. Fstatic 1/e

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Molecular Springs Ratchets

• Spasmoneme of the Vorticella
• Acrosome
• Actin polymerization

Mahdevan, L Science, 288 95, 2000.
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Spasmoneme of the Vorticella
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Actin Spring

• Acrosome needs to penetrate egg jelly.
• Spring is super-coiled- held twisted by scruin.
• Ca Ds scruin

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Supramolecular ratchets

• Pawl and ratchet analogy of actin polymerization
• How controlled? In quiescence, profilin is the
  shut-off switch. Stimulus such as pH D in
  presence of actin monomers can start.
• Listeria rides this bus

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Overall energy balance
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Conducting polymers

• Large molecular deformations (strains) induced by
  current
• Reversible Change in oxidation state

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How does muscle fatigue?

• Test of a skinned muscle fiber from EDL of rat.
• Can activate by direct stimulation of any step in
  the cascade.

Pederson, TH Science 305 1144, 2004
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F1 ATPase A rotary motor

• Can either make or break ATP, hence is reversible
• Torque of 40 pN-nM work in 1/3 rev. is 80 pn-nM
  (40 2p/3) equivalent to free energy from ATP
  hydrolysis
• Can see rotation by attaching an actin filament

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Rotary Cellular Motors

• The rotary mechanism of ATP synthase , Stock D,
  Gibbons C, Arechaga I, Leslie AGW, Walker
  JECURRENT OPINION IN STRUCTURAL BIOLOGY ,10 (6)
  672-679 DEC 2000
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• 2. ATP synthase - A marvellous rotary engine of
  the cell, Yoshida M, Muneyuki E, Hisabori
  TNATURE REVIEWS MOLECULAR CELL BIOLOGY 2 (9)
  669-677 SEP 2001
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• 3. The gamma subunit in chloroplast F-1-ATPase
  can rotate in a unidirectional and
  counter-clockwise manner Hisabori T, Kondoh A,
  Yoshida M FEBS LETTERS 463 (1-2) 35-38 DEC 10
  1999
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• 4. Constructing nanomechanical devices powered by
  biomolecular motors.C. Montemagno, G Bachand,
  Nanotechnology 10 225-2312, 1999.

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Comparative motors
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• When Lgtgt x, the chain has many bends and is
  always crumpled in solution the FJC model
  applies, with each link approximated as 2 x, and
  perfectly flexible joints.
• To count all possible curved states in a
  smooth-bending rod in solution- its a WLC-
  supercoiling is possible.

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F1 ATPase A rotary motor

• Can either make or break ATP, hence is reversible
• Torque of 40 pN-nM work in 1/3 rev. is 80 pn-nM
  (40 2p/3) equivalent to free energy from ATP
  hydrolysis
• Can see rotation by attaching an actin filament

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(www.sciencemag.org/feature/data/1049155.shl).
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