Related Experiment Video

Updated: Jul 9, 2026

Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
08:57

Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays

Published on: February 4, 2021

Peroxynitrite inhibits myofibrillar protein function in an in vitro assay of motility

Jeremy H Snook1, Jiahui Li, Brian P Helmke

  • 1Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA.

Free Radical Biology & Medicine
|November 30, 2007
PubMed

Insights

Peroxynitrite (ONOO-) damages cardiac proteins, impairing heart function. This study shows ONOO- causes contractile dysfunction by nitrating myosin and actin, impacting heart failure and ischemia/reperfusion injury.

Area of Science:

  • Cardiovascular Biology
  • Biochemistry
  • Pathophysiology

Background:

  • Ischemia/reperfusion injury and heart failure involve reactive nitrogen species.
  • Peroxynitrite (ONOO-) is a key reactive compound implicated in cardiac dysfunction.

Purpose of the Study:

  • To determine the effects of ONOO- on cardiac myosin, actin, and thin filaments.
  • To understand ONOO-'s impact on cardiac contractile dysfunction.

Main Methods:

  • Exposure of rat cardiac myosin, actin, and thin filaments to ONOO-.
  • Assessment of filament velocities, calcium sensitivity, and force using in vitro motility assays.
  • Measurement of tyrosine nitration levels.

Main Results:

  • ONOO- concentrations ≥10 μM significantly reduced filament velocities over myosin.
  • Myosin was the most sensitive protein to ONOO- induced nitration and functional deficits.
  • Combined exposure of myosin and thin filaments caused greater functional impairment than individual exposure.
  • Calcium sensitivity of thin filaments remained unchanged at 10 μM ONOO-.
  • The load supported by myosin increased threefold after ONOO- exposure.

Conclusions:

  • Nitration of myofibrillar proteins by ONOO- contributes to cardiac contractile dysfunction.
  • These findings are relevant to pathologic states involving ONOO- liberation, such as heart failure and ischemia/reperfusion injury.

More Related Videos

A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors10:28

A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors

Published on: August 17, 2019

Related Concept Videos

The Electron Transport Chain01:30

The Electron Transport Chain

The electron transport chain or oxidative phosphorylation is an exothermic process in which free energy released during electron transfer reactions is coupled to ATP synthesis. This process is a significant source of energy in aerobic cells, and therefore inhibitors of the electron transport chain can be detrimental to the cell's metabolic processes.
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q in...
Nitric Oxide Signaling Pathway01:28

Nitric Oxide Signaling Pathway

Nitric oxide (NO), an inorganic gas, acts as a potent second messenger in most animal and plant tissues. NO diffuses out of the cells that produce it and enters the neighboring cells to generate a downstream response. NO synthase (NOS) catalyzes NO production by the deamination of the amino acid arginine. There are three isoforms of NOS. Endothelial cells have endothelial NOS (eNOS), nerve and muscle cells have neuronal NOS (nNOS), and macrophages produce inducible NOS (iNOS) upon exposure to...
Actin and Myosin in Muscle Contraction01:16

Actin and Myosin in Muscle Contraction

Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
The Role of Actin and Myosin in Non-muscle Cells01:10

The Role of Actin and Myosin in Non-muscle Cells

Actin and myosin or actomyosin filaments also play a significant role in cells other than those involved in muscle contraction (which occurs within the sarcomere of muscle cells). The mechanism of non-muscle cell contractile bundles was first observed in Dictyostelium and Acanthamoeba. In non-muscle cells, two bundles are commonly found: stress fibers and actomyosin adherence belts. These contractile bundles are smaller and less organized than the ones found in muscle cells. They  are held...
Overview of Myosin Structure and Function01:15

Overview of Myosin Structure and Function

Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with their role in muscle contraction, these proteins also play a role in the intracellular transport of molecules and vesicles. There are twenty-four classes of myosins based on their domain sequence and organization. Of the twenty-four, six classes (Myosin I, Myosin II, Myosin V, Myosin VI, Myosin VII, and Myosin X)  have been well characterized.