# DYNAMICS AND ELASTICITY OF MYOSINS

> **NIH NIH R01** · UNIVERSITY OF THE PACIFIC-SAN FRANCISCO · 1988 · $99,012

## Abstract

This application is part of an effort to understand the
macromolecular mechanics of force production by muscle.
Specifically, the role of myosin crossbrige bending in force
production and energy storage will be investigated.  Three
recently discovered structural properties of the Sl portion of the
muscle myosin crossbridge will be examined:  its permanent
electric dipole moment, its segmental flexibility, and its elastic
structural distortion under the influence of an applied electric
field.  The myosin crossbridge is a protein fragment, isolated from
muscle, that is capable of combining with actin to transduce
MgATP chemical energy into mechanical energy by an unknown
structural mechanism.  The proposed experiments will test the
hypotheses that (1) the part of the myosin crossbridge called S1
bends while bound to actin in order to generate force, that (2) S1
can be reversibly and elastically distorted in order to temporarily
store the mechanical energy as elastic energy and that (3)
enzymatic removal of a 2000 dalton segment of S1 is the cause of
the trypsin-induced loss of its actin-activated MgATPase activity.

Segmental motion and elastic distortion will be measured
primarily by the method of transient electrical birefringence,
using greatly improved modern instrumentation.  By adjusting the
strength and duration of an applied electric field pulse, different
aspects of the isolated S1 structure can be investigated
quantitatively in solution.  Weak short pulses will selectively align
flexity attached smaller segments.  Weak long pulses will rotate
the entire molecule.  Strong short pulses will transiently distort
it.  The electric field produces a torque on the large permanent
electric dipole moment of S1 and the energetics of this
interaction can be measured quantitatively.  The hydrodynamic
behavior of S1 during and after the applied field will be analyzed
to obtain dynamic structural information.

The structural parameters obtained for crossbridges from muscles
from different sources, and for chemically and enzymically
modified crossbridges, will be correlated to the known muscle
properties.  The fate of a trypsin-produced 2000 dalton S1 heavy
chain fragment, and its effects on S1 structural dynamics and
ATPase activity, will be determined.

## Key facts

- **NIH application ID:** 3158162
- **Project number:** 1R01AR037499-01A2
- **Recipient organization:** UNIVERSITY OF THE PACIFIC-SAN FRANCISCO
- **Principal Investigator:** STEFAN HIGHSMITH
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $99,012
- **Award type:** 1
- **Project period:** 1988-03-01 → 1993-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3158162

## Citation

> US National Institutes of Health, RePORTER application 3158162, DYNAMICS AND ELASTICITY OF MYOSINS (1R01AR037499-01A2). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3158162. Licensed CC0.

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