Use of fluorescamine-labeled casein as a substrate for assay of proteinases

Kazuhiro Sogawa, Kenji Takahashi

    Research output: Contribution to journalArticlepeer-review

    32 Citations (Scopus)

    Abstract

    Conditions have been investigated for the use of fluorescamine-labeled casein as a substrate for fluorometric assay of proteinases. Fluorescamine-labeled casein can be prepared simply by mixing solutions of casein and fluorescamine at pH 8.0 and used without removal of the excess reagent or its hydrolysis product. The fluorescence of the labeled casein and its enzymatic digest is moderately stable in the range of pH 7.0 to 10.0. Activities can be determined by measuring the fluorescence of the hydrolysis products soluble in 0.1 M trichloroacetie acid solution at pH 4.0 after adjusting the pH of the acid-soluble fraction to 7.7. This method is suited for assay of proteinases active at neutral to slightly alkaline pH values, and is capable of quantitating about 0.05 μg of trypsin or 0.5 μg of α-chymotrypsin or papain. The assay can be done in the presence of large amounts of contaminating amino acid, protein and/or exopeptidases which may interfere with the ordinary assay of proteinases.

    Original languageEnglish
    Pages (from-to)1783-1787
    Number of pages5
    JournalJournal of biochemistry
    Volume83
    Issue number6
    DOIs
    Publication statusPublished - 1978 Jun

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology

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