Inhibiteurs anti-trypsine et activit�s prot�olytiques des Albumines de graine de Vigna unguiculata

Royer, Annick; Miège, Marie-Noëlle; Grange, Adenike; Miège, Jacques; Mascherpa, Jean-Michel

doi:10.1007/bf00390817

Cited by 24 publications

(4 citation statements)

References 13 publications

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“…Because C. rnuculatus larvae develop within seeds of cowpeas, which are known to contain various proteinases and esterases [23,24], we prepared seed extracts to determine if seed proteinases might contribute to the observed proteolytic and esterolytic activity found in the larval gut lumen contents. Table 5 shows that BAPNA-ase activity in cowpea seed extracts was about four times that in C. maculatus crude gut proteinase preparations at pH 7.8.…”

Section: Resultsmentioning

confidence: 99%

Partial characterization of a major gut thiol proteinase from larvae of Callosobruchus maculatus F.

Kitch

Murdock

1986

Arch Insect Biochem Physiol

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Much of the proteolytic activity in the digestive tract of Callosobruchus maculatus larvae can be attributed to a thiol proteinase(s) that hydrolyzes 3H]methemoglobin by larval gut homogenates. Proteolytic activity in the larval gut was located in the lumen contents and thus appears to play a major role in extracellular digestion. The pH of the larval midgut is slightly acidic, and midgut contents exhibit a negative redox potential, conditions supporting the activity of a thiol proteinase. The significance of these findings is discussed with reference to the vulnerability of this digestive proteinase as a target for existing or genetically engineered plant chemical defenses.

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Section: Resultsmentioning

confidence: 99%

Partial characterization of a major gut thiol proteinase from larvae of Callosobruchus maculatus F.

Kitch

Murdock

1986

Arch Insect Biochem Physiol

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“…This observation has led to the suggestion that the onset of storage protein metabolism in legume seedlings is due to the activation of proteases in the protein bodies, and that this activation is causally related to the decline in protease-inhibitory activity (8,9). However, such a causal relationship has never been established and no one has demonstrated autolytic proteolysis in isolated protein bodies.…”

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confidence: 96%

Regulation of reserve protein metabolism in the cotyledons of mung bean seedlings

Chrispeels

Baumgärtner

Harris

1976

Proc. Natl. Acad. Sci. U.S.A.

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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.The cotyledons of leguminous seeds are rich in reserve proteins which are metabolized during seedling growth. These proteins are located in special organelles, called protein bodies, consisting of a protein matrix and a limiting membrane (1). Growth of the seedlings is accompanied by an increase in the proteolytic activity in the cotyledons (2, 16) due to the appearance of a protease with endopeptidase activity (4). Ultrastructural studies suggest that proteolysis occurs within the protein bodies. The protein matrix disappears and the protein bodies enlarge. Eventually all the "empty" protein bodies merge to form a central vacuole (5). Protein bodies isolated from dry seeds or seeds germinated for 1 day contain proteolytic and other hydrolytic enzymes and these organelles are considered to be an integral component of the lytic compartment of the cell (for a review, see ref. 6). Both reserve proteins and proteases accumulate in the protein bodies during seed maturation, and it has been suggested that this allows proteolysis to begin soon after seed imbibition (7).Cotyledons of legurninous seeds are rich in protease inhibitors which decrease during early seedling growth (8, 3). This observation has led to the suggestion that the onset of storage protein metabolism in legume seedlings is due to the activation of proteases in the protein bodies, and that this activation is causally related to the decline in protease-inhibitory activity (8, 9). However, such a causal relationship has never been established and no one has demonstrated autolytic proteolysis in isolated protein bodies.We now present evidence in support of an entirely different control mechanism for the metabolism of the reserve proteins in legume cotyledons. Our results with mung beans show that the endopeptidase responsible for reserve protein breakdown is synthesized de novo and becomes associated with the protein bodies. Ultrastructural evidence suggests that vesicles originating from the rough endoplasmic reticulum may mediate the transport of the enzyme from its site of...

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“…Inhibitors of endogenous plant proteases have been found in rice (9), barley (14), and in mung bean (1). However, several studies led to the conclusion that the great increase in endopeptidase in the storage tissues during seed germination cannot be accounted for by the inactivation of an "equivalent amount" of inhibitors (1, 14).Recently Miege and collaborators (13,17,18) …”

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confidence: 99%

“…Recently Miege and collaborators (13,17,18) revived the proposal that the decrease in trypsin inhibitory activity during seedling growth results in the unmasking of one or more proteases. Removal of trypsin inhibitor by means of a trypsin affinity column from crude extracts of cowpea cotyledons brought about a 2.5-fold increase in the caseolytic activity of these extracts (17).…”

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confidence: 99%

Trypsin Inhibitor in Mung Bean Cotyledons

Chrispeels¹,

Baumgärtner²

1978

Plant Physiol.

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Trypsin inhibitor was purHied to homogeneity from seeds of the mung bean ( Vigna radiats ILl Wilczek). The protease inhibitor has the foUowing properties: inhibitory activity toward trypsin, but not toward chymotrypsin; isoelectric point at pH 5.05; molecular weight of 11,000 to 12,000 (sodium dodecyl sulfate gel electrophoresis) or 14,000 (gel ifitration); immunological cross-reactivity against extracts of black gram and black-eyed pea, but not against soybean; no inhibitory activity against vicilin peptidohydrolase, the principal endopeptdase in the cotyledon of mung bean seedlings.The trypsin inhibitor content of the cotyledons declines in the course of seedling growth and the presence of an inactivating factor can be demonstrated by incubating crude extracts in the presence of,B-mercaptoethanol. This inactivating factor may be a protease as vicilin peptidohydrolase rapidly inactivates the trypsin inhibitor. Removal of trypsin inhibitory activity from crude extracts by means of a trypsin affinity column does not result in an enhancement of protease activity in the extracts. Seed germination and the subsequent growth of the young seedlings are characterized by the breakdown of the reserve proteins of the seed. This breakdown is accompanied at an enhancement of protease-especially endopeptidase-activity, as well as by a decrease in protease inhibitor activity. Seeds of the Leguminosae, the Graminae, and the Solanaceae are an abundant source of protease inhibitors, and especially trypsin-or chymotrypsin-inhibitors, but the role of these inhibitors in the physiology of the plants is not understood. It has been proposed that these proteinaceous inhibitors may be storage proteins, that they play a role in masking the activity of preexisting plant proteases, and that they protect the seeds against pathogens and phytophagous insects (for reviews see Liener and Kakade (11) Shain and Mayer (20) reported that a trypsin inhibitor in lettuce seeds inhibits an endogenous trypsin-like enzyme which increases during germination, but the function of this enzyme in reserve protein breakdown is unknown. Inhibitors of endogenous plant proteases have been found in rice (9), barley (14), and in mung bean (1). However, several studies led to the conclusion that the great increase in endopeptidase in the storage tissues during seed germination cannot be accounted for by the inactivation of an "equivalent amount" of inhibitors (1, 14).Recently Miege and collaborators (13,17,18)

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Inhibiteurs anti-trypsine et activit�s prot�olytiques des Albumines de graine de Vigna unguiculata

Cited by 24 publications

References 13 publications

Partial characterization of a major gut thiol proteinase from larvae of Callosobruchus maculatus F.

Partial characterization of a major gut thiol proteinase from larvae of Callosobruchus maculatus F.

Regulation of reserve protein metabolism in the cotyledons of mung bean seedlings

Trypsin Inhibitor in Mung Bean Cotyledons

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