Radial diffusion as a sensitive method for screening endopeptidase activity in plant extracts

✍ Scribed by Karlheinz Santarius; Clarence Ryan

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 529 KB
• Volume: 77
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(77)90283-4

✦ Synopsis

The radial diffusion assay was evaluated for its usefulness as a simple, inexpensive assay for screening endopeptidase activity in vegetative plant tissues. Various substrates embedded in agar were tested with trypsin and a-chymotrypsin to select those with the greatest sensitivity for detecting proteolysis. Gelatin was the most sensitive substrate for assays and could be utilized to detect less than 1 ng of a-chymotrypsin and trypsin per 25 ~1 of solution. Several exopeptidases could not be detected by this method at IOOO-fold higher concentrations of enzymes. Extracts of leaves of 17 genera representing 12 families were surveyed semiquantitatively for proteolytic activity. The leaves of genera of the Solanaceae, Leguminosae, Gramineae, and Compositae exhibited the highest levels of activity. Only leaves from Syringa vulgaris (Oleaceae) did not exhibit proteolytic activity with this assay. The method of radial diffusion was successfully employed for the initial concentration and purification of a proteinase from potato leaves.