# TRANSIENT SPECTROSCOPY OF MUSCLE

> **NIH NIH R01** · UNIVERSITY OF MINNESOTA · 1993 · $236,882

## Abstract

The long-term goal of this research is to understand the coupling of
molecular dynamics to ATPase enzyme action, focussing on the two
principal ATP-driven energy transduction systems in vertebrate skeletal
muscle: the myosin-actin system (contraction, force-generation), and the
Ca-ATPase of sarcoplasmic reticulum (relaxation, active Ca transport).
Because these processes are essentially dynamic, we focus on direct
detection of protein motions, using site-specific spectroscopic probes:
electron paramagnetic resonance (EPR) with nitroxide spin labels, and
optical anisotropy with fluorescent and phosphorescent dyes.  These
methods are chosen because they have sufficient sensitivity and
selectivity to detect specific molecular motions in a complex system
under physiological conditions.  The present project focuses on
spectroscopic measurements during the transient phase of the ATPase
reaction cycle.  This is accomplished by initiating spectroscopic data
acquisition, then using laser flash photolysis of "caged" compounds
(e.g., caged ATP, caged Ca), then observing the millisecond-time-resolved
spectroscopic response to the resulting step change in ligand (e.g., ATP,
Ca) concentration.  The following specific aims will be pursued: (1)
Develop improved methods for obtaining and analyzing transient
spectroscopic (EPR and optical) signals from muscle fibers and membranes,
using flash photolysis of caged compounds.  (2) Use this technology to
probe molecular dynamics and interactions in purified myosin, actin, and
their complexes. (3) Probe molecular orientation, motion, and interaction
in skinned muscle fibers, during the transient phase of contraction. (4)
Detect transient rotational dynamics of the Ca-ATPase during calcium
transport in SR membranes.

Collaborative studies will be carried out with experts in the transient
biochemical and mechanical kinetics of both systems, in an effort to
obtain direct correlations between molecular dynamics and physiological
transitions.  We will use several different caged compounds, to probe
different parts of the ATPase cycle, and we will perform spectroscopic
experiments under conditions known to affect the physiological
transients.  While our central goal is to provide new and essential
information about the molecular events in muscle contraction and
relaxation, we also hope that the technology we are developing will prove
effective in a wide range of biophysical energy transduction problems.

## Key facts

- **NIH application ID:** 3159984
- **Project number:** 5R01AR039754-05
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **SAM.gov UEI:** KABJZBBJ4B54
- **Principal Investigator:** David D Thomas
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1993
- **Award amount:** $236,882
- **Award type:** 5
- **Project period:** 1988-12-01 → 1996-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3159984

## Citation

> US National Institutes of Health, RePORTER application 3159984, TRANSIENT SPECTROSCOPY OF MUSCLE (5R01AR039754-05). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3159984. Licensed CC0.

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