Protein Mobilization and Proteolytic Enzyme Activities during Seed Germination of Broad Bean (Vicia faba L.) (original) (raw)
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Protein Mobilization and Proteolytic Enzyme Activities
The protein mobilization from attached and detached seeds of Vicia faba L. cv. Eresen 87 (Fabaceae) was investigated. While the total soluble protein content decreased, the free amino acid content increased during the 7 days germination period. Among the three proteolytic enzymes, only endopeptidase activity was found to be affected by the removal of the embryonic axis. Leucine aminopeptidase activity was high at the beginning, then it decreased; carboxypeptidase activity reached the highest value at day 5. In order to examine the effects of plant growth regulators on detached cotyledons incubated with plant growth regulators [10 Ð4 m benzyladenine (BA), gibberellic acid (GA 3), indole acetic acid (IAA) and 10 Ð5 m abscisic acid (ABA)], only benzyladenine was found promotive on protein mobilization. Our results suggest that the removal of the embryonic axis in seeds of Vicia faba L. cv. Eresen 87 decreases protein mobilization and endopeptidase activity.
Regulation of reserve protein metabolism in the cotyledons of mung bean seedlings
Proceedings of the National Academy of Sciences, 1976
Seedling growth in mung beans ( Phaseolus aureus , Roxb.) is accompanied by the metabolism of the reserve proteins, and the appearance in the cotyledons of a proteolytic enzyme with endopeptidase activity. Enzyme activity increases 25-fold during the first 5 days of growth. Cotyledon extracts prepared from seeds imbibed for 24 hr with water do not react with rabbit endopeptidase antiserum, which suggests that the enzyme is not present in the seeds as a zymogen. Labeling experiments show that the enzyme is synthesized in the course of seedling growth. The endopeptidase is localized in the protein bodies, and the specific activity of the enzyme in these organelles increases 30-fold. Ultrastructural studies show that the rough endoplasmic reticulum proliferates and may give rise to vesicles which fuse with the protein bodies prior to reserve protein digestion. These vesicles could be the primary lysosomes which transport the enzyme from its site of synthesis to its site of action.
Zeitschrift fü Pflanzenphysiologie
Changes in the nitrogen contents and in the extractable actlVltIes of amino-, carboxyand endopeptidases were analyzed in bush beans (Phaseolus vulgaris 1.) throughout the life cycle. Two types of casein digesting enzymes (endopeptidases) were found. One type was the main activity extracted from cotyledons during germination with a pH optimum around pH 5.5 and was stimulated by the presence of mercaptoethanol in the incubation medium. The other type showed high activities in leaf extracts, was most active around pH 7 and was slightly inhibited by the presence of 0.1 Ofo mercaptoethanol in the incubation medium.
Physiologia Plantarum, 2001
Removal of the embryonic axis prevents the normal decline of and throughout the entire time from removal of the axis. The carboxypeptidase (Cpase) I in mung bean seedling cotyledons. difference between detached cotyledons in the absence and presence of calcium was greatest when the cotyledons were Cpase I activity and protein, the latter manifested on western detached 4 -6 days after seed imbibition. Loss of Cpase I blots, almost completely disappear about 24 h before the activity and protein can be demonstrated in vitro, with the cotyledon abscises. Of the 3 proteolytic enzyme patterns, only that of Cpase I can be restored by an exogenous supply of 10 maximum level of Cpase I-degrading activity measured 4 days mM CaCl 2 in the agar growth medium. The calcium effect is after seed imbibition under the same growth conditions used to study the calcium effect. It is sensitive to pepstatin and has a dependent on [CaCl 2 ] and is not manifested in the presence of pH optimum of 3, suggesting that this Cpase I-degrading chelators and calcium channel blockers. For detached cotyledons to show the normal low level of Cpase I by the eighth day activity is due to an aspartic protease. of growth, calcium had to be supplied during seed imbibition
Control of storage protein accumulation during legume seed development
Journal of Plant Physiology, 2001
The regulation of partitioning of carbohydrate skeletons into different storage products of developing seeds is still not understood. We explored two ways to gain more insight in the process. First we analyzed mechanisms that control storage protein accumulation in Vicia faba seeds of contrasting protein content. As expected, the seeds of the high protein genotypes (HP) contained more protein and total nitrogen as compared to the low protein genotypes (LP) whereas starch and total amounts of carbon were not altered. There was no major difference in the proportion of amino acids delivered from seed coats into the endospermal cavity of either HP or LP genotypes. However, HP genotype cotyledons contained twofold higher levels of free amino acids at the later developmental stages when their higher protein content was expressed. After four hours of incubation, in vitro uptake rates of 14 C glutamine by HP cotyledons were significantly higher for the protein rich cotyledons indicating a possible higher capacity to take up amino acids. In both genotypes 14 C-glutamine was rapidly converted into glutamate and then partly decarboxylated to γ-amino butyric acid. However, in the HP cotyledons the ratio of 14 C-glutamine to 14 C-glutamate was higher as compared to the LP cotyledons reflecting the observed higher glutamine uptake rate. In a second approach we studied Vicia narbonensis seeds which expressed ADP glucose pyrophosphorylase in antisense orientation. These seeds contained less starch and more sucrose and water but also more protein. In addition, blocking the starch synthesis pathway caused pleiotropic effects on water content and induced temporal changes in seed development. The resulting longer seed fill duration period could partially explain the observed elevated protein content in the AGP-antisense seeds. Key words: assimilate partitioning-storage protein-amino acid metabolism-nutrient transportlegume seed development Abbreviations: AAP amino acid permeases.-AGP ADP-glucose pyrophosphorylase.-GABA γ-aminobutyric acid.-HP high protein.-LP low protein.-PEPC phosphoenolpyruvate carboxylase * This paper is more focussed than the oral presentation at the meeting since a more general review has been published recently (Wobus and Weber 1999).
Protein Deposition and Mobilization in Seeds
2006
Cereal and Leguminous plant’s seeds take a large place of human food consumption. The germinating seed depends on its reserve material till the photosynthetic system develops. Storage proteins deposited in the seed during the maturation and have a purpose to provide free amino acids to the growing seedling. The present knowledge on protein storage during the seed development and enzymes involved in mobilization of the storage proteins has been summarized.
European Journal of Biochemistry, 1995
Proteinase B, an asparagine-specific endopeptidase, has been purified from germinating vetch (Vicia sativa L.) seeds. The final preparation consists of two enzymically active proteins with molecular masses of approximately 39 kDa and 37 kDa. Synthetic substrates were used to confirm cleavage specificity of the proteinase B preparation. As expected, the enzyme cleaves the substrates at the C-terminal side of Asn residues. The octapaptide ETRNGVEE was digested most efficiently. When Gly was replaced by Ile or Glu, cleavage took place with lower efficiency. Polyclonal antibodies displayed both proteins in cotyledon extracts of germinated vetch seeds. In addition, a strong cross-reacting protein band was found in cotyledon extracts of developing seeds, indicating the presence of a very similar enzyme during seed development.
The changes of protein patterns during one week of germination of some legume seeds and roots
This study was carried out in order to evaluate some Egyptian legume seeds (Vicia faba, Cicer arietinum and Lupinus termes) as raw and germinated foods, as sources of plant proteins. The work was extended to study the changes of the seed and root proteins during 7 days of germination. The results are sum-marised as follows: (1) The proteins of ungerminated seeds were resolved on SDS-PAGE into a number of bands and their molecular weights were determined: chick-peas, 19 (8-78 kDa); faba beans, 20 (1 l-96 kDa) and lupins 19 (14-86 kDa). (2) The changes in the seed and root proteins during 7 days of germination of the V. faba, C. arietinum and L. termes showed the following: l