Biochemical and molecular characterization of alpha-D-galactosidase from coffee beans
| Autor: | Pierre Marraccini, Sylvianne Lechat, David Pridmore, Alain Deshayes, W.John Rogers, Dominique Granato, Victoria Caillet, Françoise Lausanne, Vincent Petiard |
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| Rok vydání: | 2005 |
| Předmět: |
Physiology
F60 - Physiologie et biochimie végétale Canephora Molecular Sequence Data Germination Plant Science Coffea canephora Coffee F30 - Génétique et amélioration des plantes Endosperm Complementary DNA Genetics Electrophoresis Gel Two-Dimensional Variété Amino Acid Sequence RNA Messenger Paroi cellulaire Gel electrophoresis chemistry.chemical_classification Mannane biology Sequence Homology Amino Acid Coffea arabica food and beverages biology.organism_classification Blotting Southern Alpha galactosidase Enzyme Biochemistry chemistry alpha-Galactosidase Seeds Fève de café Activité enzymatique Développement biologique |
| Zdroj: | Plant Physiology and Biochemistry |
| ISSN: | 0981-9428 |
| Popis: | [alpha]-D-Galactosidase ([alpha]-Gal; EC 3.2.1.22) is one of three principal enzymes involved in the modification or degradation of plant cell wall galactomannans. In the present paper it is shown that [alpha]-galactosidase activities in field-grown coffee beans are variable amongst cultivars of the two species investigated (Coffea arabica and C. canephora var. Robusta). Higher activities were found in Arabica cultivars. Using beans from greenhouse-cultivated C. arabica as a model, we showed that [alpha]-Gal activity was undetectable in the bean perispem tissue, but increased gradually during the endosperm development, to reach a peak at approximately 30 weeks after flowering (WAF) which coincided with the hardening of the endosperm. [alpha]-Gal-specific transcripts detected at 22 and 27 WAF accompanied the peak of [alpha]-Gal activity, but were reduced to be undetectable in mature beans at 30 WAF, while [alpha]-Gal activity still persisted. Two isoforms were distinguished in 2-DE profiles of crude protein extracts by N-terminal sequencing analysis. Analysis of two-dimensional gel electrophoresis profiles demonstrated that both isoforms accumulated in a linear fashion throughout grain maturation. [alpha]-Gal activity was also observed to increase to high levels during in vitro germination of coffee beans suggesting an important function of this enzyme in this process. [alpha]-Gal cDNA sequences from Arabica and Robusta were sequenced and their deduced proteins appeared to be very similar, differing by only eight amino acids. Southern-blot analysis suggests that the enzyme was encoded by at least two genes in C. arabica that could explain the existence of the two isoforms identified in 2-DE profiles. |
| Databáze: | OpenAIRE |
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