Some citrus chitinases also possess chitosanase activities |
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Authors: | W. F. Osswald J. P. Shapiro R. E. McDonald R. P. Niedz R. T. Mayer |
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Affiliation: | (1) U.S. Department of Agriculture, Agricultural Research Service, U.S. Horticultural Research Laboratory, 2120 Camden Road, 32803-1419 Orlando, Florida, USA;(2) Present address: Institute for Botany, Technical University of Munich, Arcisstrasse 21, 80333 Munich, (Germany) |
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Abstract: | Several acidic chitinase and chitosanase isoforms were found in 4-week-old nonembryogenic sweet orange (Valencia [Citrus sinensis (L.) Osbeck]) callus tissue. Two isoforms (designated A1-CF1 and A1-CF2) were purified to homogeneity using HPLC size exclusion, anion exchange, and chromatofocusing techniques. Both hydrolase isoforms exhibited activity with either colloidal chitin or solubilized shrimp shell chitosan. Specific activities for the purified isoforms could not be calculated because of the lack of protein and contamination of ampholytes. However, the specific activities for chitinase and chitosanase after anion exchange were respectively 404 nmol GlcNAc per min per mg protein and 2,475 nmol GlcN per min per mg protein. The Mr for both enzymes was 30,500. The homogeneous proteins cross-reacted in western blots with antiserum against a basic class I potato leaf chitinase. |
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Keywords: | Chitosanases chitinases hydrolases sweet orange callus tissue immunoblotting pathogenesis-related proteins |
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