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Clostridiopeptidase B inhibition by plasma marcroglobulins and microbial antiproteases

E Giroux, B B Vargaftig

    Biochimica Et Biophysica Acta
    |August 7, 1978
    PubMed

    Insights

    Clostridiopeptidase B activity is inhibited by plasma macroglobulins and specific inhibitors like leupeptin and antipain. These findings are crucial for understanding enzyme regulation and kinin release pathways.

    Area of Science:

    • Biochemistry
    • Enzymology
    • Protease Inhibitors

    Background:

    • Clostridiopeptidase B (EC 3.4.22.8) is a protease with amidase activity.
    • Understanding its regulation is key to elucidating biological pathways involving kinin generation.

    Purpose of the Study:

    • To investigate the inhibitory effects of various protease inhibitors on Clostridiopeptidase B.
    • To characterize the inhibition of enzyme activity and its role in kinin release.

    Main Methods:

    • Enzyme inhibition assays using different classes of inhibitors.
    • Analysis of amidase and protease activities of Clostridiopeptidase B.
    • Assessment of kinin release in plasma.

    Main Results:

    • Clostridiopeptidase B was not inhibited by common trypsin inhibitors but showed reduced activity at high concentrations.
    • Human plasma alpha 2-macroglobulin effectively inhibited both amidase and protease activities.
    • Rat and dog plasmas contained potent high molecular weight inhibitors.
    • Leupeptin and antipain demonstrated significant inhibition of Clostridiopeptidase B (Ki values of 2 x 10(-8) M and 3 x 10(-8) M, respectively).
    • These inhibitors were also potent in blocking Clostridiopeptidase B-induced kinin release in dog plasma.

    Conclusions:

    • Clostridiopeptidase B is regulated by specific plasma macroglobulins and small molecule inhibitors.
    • Leupeptin and antipain are effective inhibitors of Clostridiopeptidase B and its kinin-releasing activity.
    • Differential inhibition patterns may relate to indirect vs. direct kinin generation mechanisms.

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