Characterization of seven basic endochitinases isolated from cell cultures of Citrus sinensis (L.)
| Autor: | Randall P. Niedz, C. J. Hearn, E. Berdis, Richard T. Mayer, Roy E. McDonald, T. G. McCollum, Hamed Doostdar |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Citrus
Glycoside Hydrolases Molecular Sequence Data Ultrafiltration Plant Science Substrate Specificity chemistry.chemical_compound Genetics Tetrasaccharide Amino Acid Sequence Chitosanase Histidine Pathogenesis-related protein chemistry.chemical_classification biology Chitinases Oligosaccharide Molecular Weight Isoelectric point chemistry Biochemistry Chitinase biology.protein Electrophoresis Polyacrylamide Gel Muramidase Lysozyme |
| Zdroj: | Planta. 200 |
| ISSN: | 1432-2048 0032-0935 |
| DOI: | 10.1007/bf00200295 |
| Popis: | Seven endochitinases (EC 3.2.1.14) (relative molecular masses 23,000-28,000 and isoelectric points 10.3-10.4) were purified from nonembryogenic Citrus sinensis L. Osbeck cv. Valencia callus tissue. The basic chitinase/lysozyme from this tissue (BCLVC) exhibited lysozyme, chitinase and chitosanase activities and was determined to be a class III chitinase. While BCLVC acted as a lysozyme at pH 4.5 and low ionic strength (0.03) it acted as a chitinase/chitosanase at high ionic strengths (0.2) with a pH optimum of ca. 5. The lysozyme activity of BCLVC was inhibited by histamine, imidazole, histidine and the N-acetyl-D-glucosamine oligosaccharide (GlcNAc)3. The basic chitinase from cv. Valencia callus, BCVC-2, had an N-terminal amino acid sequence similar to tomato and tobacco AP24 proteins. The sequences of the other five chitinases were N-terminal blocked. Whereas BCLVC was capable of hydrolyzing 13.8-100% acetylated chitosans and (GlcNAc)4-6 oligosaccharides, BCVC-2 hydrolyzed only 100% acetylated chitosan, and the remaining enzymes expressed varying degrees of hydrolytic capabilities. Experiments with (GlcNAc)2-6 suggest that BCLVC hydrolysis occurs in largely tetrasaccharide units whereas hydrolysis by the other chitinases occurs in disaccharide units. Cross-reactivities of the purified proteins with antibodies for a potato leaf chitinase (AbPLC), BCLVC, BCVC-3, and tomato AP24 indicate that these are separate and distinct proteins. |
| Databáze: | OpenAIRE |
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