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The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis
19:16

The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis

Published on: March 17, 2010

Soluble and particulate forms of muscle alkaline proteinase show differential sensitivity to endogenous inhibitor(s)

F Ismail, W Gevers

    Biochemistry International
    |February 1, 1983
    PubMed

    Insights

    A chymostatin-sensitive protease in rat skeletal muscle degrades myofibrillar and cytosolic proteins. Its activity is influenced by ionic strength and cytosolic inhibitors, impacting protein breakdown in muscle tissue.

    Area of Science:

    • Biochemistry
    • Muscle Physiology
    • Proteolysis

    Background:

    • Rat skeletal muscle myofibrils contain proteases.
    • These proteases degrade myofibrillar and cytosolic proteins.
    • Protease activity is modulated by ionic strength and inhibitors.

    Purpose of the Study:

    • To characterize a chymostatin-sensitive protease in rat skeletal muscle.
    • To investigate the influence of ionic strength on protease activity.
    • To examine the role of cytosolic inhibitors on protease function.

    Main Methods:

    • Preparation of membrane-free washed myofibrils and muscle cytosol from rat skeletal muscle.
    • Assay of protease activity at varying pH and ionic strength.
    • Gel chromatography for protease separation.
    • Dialysis to assess enzyme precipitation and inhibitor effectiveness.

    Main Results:

    • The protease exhibited optimal activity at pH 8.5.
    • Activity was lower at low ionic strength on insoluble myofilaments compared to high salt concentrations.
    • Cytosolic protein degradation was more pronounced at low ionic strength due to inhibitor ineffectiveness.
    • Cytosolic inhibitors were only effective against the soluble enzyme at high ionic strength.

    Conclusions:

    • A chymostatin-sensitive protease is present in rat skeletal muscle myofibrils.
    • Ionic strength significantly affects protease activity and substrate accessibility.
    • Cytosolic inhibitors regulate protease activity, with effectiveness dependent on ionic strength and protein solubility.

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