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Carlos Faro - One of the best experts on this subject based on the ideXlab platform.
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cardosins in postembryonic development of cardoon towards an elucidation of the biological function of plant Aspartic Proteinases
Protoplasma, 2008Co-Authors: Claudia Pereira, Carlos Faro, Diana Soares Da Costa, Susana Pereira, F De Moura Nogueira, P M Albuquerque, Jorge Teixeira, Jose PissarraAbstract:Following on from previous work, the temporal and spatial accumulation of the Aspartic Proteinases (EC 3.4.23) cardosin A and cardosin B during postembryonic seed development of cardoon (Cynara cardunculus) was studied. mRNA and protein analyses of both cardosins suggested that the proteins accumulate during seed maturation, and that cardosin A is later synthesised de novo at the time of radicle emergence. Immunocytochemistry revealed that the precursor form of cardosin A accumulates in protein bodies and cell walls. This localisation in seeds is different from that previously described for cardoon flowers, suggesting a tissue-dependent targeting of the protein. It is known that procardosins are active and may have a role in proteolysis and processing of storage proteins. However, the presence of procardosin A in seeds could be related to the proposed role of the plant-specific insert in membrane lipid conversion during water uptake and solute leakage in actively growing tissues. This is in accordance with the recently proposed bifunctional role of Aspartic proteinase precursor molecules that possess a membrane-destabilising domain in addition to a protease domain. Mature cardosin B, but not its mRNA, was detected in the first hours after seed imbibition and disappeared at the time of radicle emergence. This extracellular Aspartic protease has already been implicated in cell wall loosening and remodelling, and its role in seed germination could be related to loosening tissue constraints for radicle protusion. The described pattern of cardosin A and B expression suggests a finely tuned developmental regulation and prompts an analysis of their possible roles in the physiology of postembryonic development.
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characterization of recombinant cdr1 an arabidopsis Aspartic proteinase involved in disease resistance
Journal of Biological Chemistry, 2007Co-Authors: Isaura Simoes, Rosario Faro, Carlos FaroAbstract:Abstract The Arabidopsis thaliana constitutive disease resistance 1 (CDR1) gene product is an Aspartic proteinase that has been implicated in disease resistance signaling (Xia, Y., Suzuki, H., Borevitz, J., Blount, J., Guo, Z., Patel, K., Dixon, R. A., and Lamb, C. (2004) EMBO J. 23, 980–988). This apoplastic enzyme is a member of the group of “atypical” plant Aspartic Proteinases. As for other enzymes of this subtype, CDR1 has remained elusive until recently as a result of its unusual properties and localization. Here we report on the heterologous expression and characterization of recombinant CDR1, which displays unique enzymatic properties among plant Aspartic Proteinases. The highly restricted specificity requirements, insensitivity toward the typical Aspartic proteinase inhibitor pepstatin A, an unusually high optimal pH of 6.0–6.5, proteinase activity without irreversible prosegment removal, and dependence of catalytic activity on formation of a homo-dimer are some of the unusual properties observed for recombinant CDR1. These findings unveil a pattern of unprecedented functional complexity for Arabidopsis CDR1 and are consistent with a highly specific and regulated biological function.
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Aspartic proteinase content of the arabidopsis genome
Current Protein & Peptide Science, 2005Co-Authors: Carlos FaroAbstract:Abstract: The sequence of the Arabidopsis genome has given us information about one plant's complement of AsparticProteinases. Using an in silico analysis based on the homology to known Aspartic proteinase genes, we have uncovered 51sequences that potentially encode these enzymes. This is substantial more than the number predicted for other eukaryoticsystems. We have grouped the deduced amino acid sequences into 3 classes - typical plant Aspartic proteinase, nucellin-like and atypical Aspartic proteinase sequences-, depending on their putative domain organizations and their active site se-quence motifs. Searching databases has revealed cDNAs or ESTs for nearly 90% of these genes. Sequence analysis usingsoftware that detects targeting signals indicates most of the predicted proteins have the expected localization in the secre-tory system although several of these are membrane bound. The analysis also predicts 8 chloroplast localized proteins and2 mitochondria-localized Aspartic proteinase-like proteins. The wide variety of structures and subcellular locations impliesmultiple functions for Aspartic Proteinases in plants.
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Aspartic proteinase content of the arabidopsis genome
Current Protein & Peptide Science, 2005Co-Authors: Carlos FaroAbstract:Abstract: The sequence of the Arabidopsis genome has given us information about one plant's complement of AsparticProteinases. Using an in silico analysis based on the homology to known Aspartic proteinase genes, we have uncovered 51sequences that potentially encode these enzymes. This is substantial more than the number predicted for other eukaryoticsystems. We have grouped the deduced amino acid sequences into 3 classes - typical plant Aspartic proteinase, nucellin-like and atypical Aspartic proteinase sequences-, depending on their putative domain organizations and their active site se-quence motifs. Searching databases has revealed cDNAs or ESTs for nearly 90% of these genes. Sequence analysis usingsoftware that detects targeting signals indicates most of the predicted proteins have the expected localization in the secre-tory system although several of these are membrane bound. The analysis also predicts 8 chloroplast localized proteins and2 mitochondria-localized Aspartic proteinase-like proteins. The wide variety of structures and subcellular locations impliesmultiple functions for Aspartic Proteinases in plants.
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the saposin like domain of the plant Aspartic proteinase precursor is a potent inducer of vesicle leakage
Journal of Biological Chemistry, 2000Co-Authors: Conceicao Egas, Euclides Pires, Nuno Lavoura, Rosa Resende, Rui M M Brito, Maria Pedroso C De Lima, Carlos FaroAbstract:Abstract A unique feature of plant Aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH- and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant Aspartic Proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plant-specific insert, alone or in conjunction with the proteolytic activity of plant Aspartic Proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.
Peter Brodelius - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning of Aspartic Proteinases from flowers of cynara cardunculus subsp flavescens cv cardoon and centaurea calcitrapa
Advances in Experimental Medicine and Biology, 1998Co-Authors: Peter Brodelius, Ana Domingos, M Cordeiro, P Mercke, A Clemente, M S PaisAbstract:Aspartic Proteinases of human, animal, parasite, fungal and retroviral origin have been extensively investigated. The 3-D structures of several such enzymes have been solved and they all have a number of features in common.1 By contrast, relatively little is known about Aspartic Proteinases in plants. During the last few years, however, an increasing number of studies on plant Aspartic Proteinases have been carried out.2,3 We are since a few years involved in studies of milk-clotting enzymes of plant origin.
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substrate specificity and molecular modelling of Aspartic Proteinases cyprosins from flowers of cynara cardunculus subsp flavescens cv cardoon
Advances in Experimental Medicine and Biology, 1998Co-Authors: M Cordeiro, Kunchur Guruprasad, Ben M Dunn, T L Blundell, M S Pais, T Lowther, Peter BrodeliusAbstract:Water extracts of dried flowers of Cynara cardunculus subsp. flavescens cv. cardoon have been traditionally used in Portugal to produce artisanal cheeses (e.g. Serpa and Serra cheeses) with ewe’s milk. The clotting activity is due to three heterodimeric Aspartic Proteinases (cyprosin 1, cyprosin 2 and cyprosin 3) which have been purified from flowers.1 A native Mr of around 49000 was determined for the three cyprosins by SDS-PAGE. The subunit sizes are 32.5 + 16.5, 33.5 + 16.5, and 35.5 + 13.5 kD for cyprosin 1, 2 and 3, respectively. Gel filtration chromatography indicated somewhat lower native Mrs (41–45000). The enzymes are N-glycosylated (high mannose type) and express maximum activity around pH 4.1 using a synthetic peptide as substrate.
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Aspartic Proteinases cyprosins from cynara cardunculus spp flavescens cv cardoon purification characterisation and tissue specific expression
Advances in Experimental Medicine and Biology, 1995Co-Authors: Peter Brodelius, M C Cordeiro, M S PaisAbstract:Flowers of C cardunculus (cardoon) have been used in Portugal since many centuries to make cheese with raw ewe or/and goat milk. Several types of cheeses are well known and highly appreciated for their taste and quality. Examples are Serra, Serpa and Azeitao. The skills of making these artisanal cheeses have been inherited over generations within the same families and are still used today. Farmers collect the mature flowers or upper part of styles during June and July and store them in dry places to be used for clotting of milk during the next seasons, autumn and winter. Traditionally the cheeses are made mainly with fresh ewe’s milk. The Proteinases are extracted from flowers with lukewarm water. This extract is filtered through a cloth which contains a spoon of salt. The milk (2–4 1 per cheese) is also passed through the cloth and then left for coagulation during 30–45 minutes. The whey is removed by collecting the curd in another piece of cloth, and afterwards it is brought into shape with a mold. The ripening period is around 6 weeks at 12°C (room temperature in some regions during winter) in a humid and aerated environment.
M S Pais - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning of Aspartic Proteinases from flowers of cynara cardunculus subsp flavescens cv cardoon and centaurea calcitrapa
Advances in Experimental Medicine and Biology, 1998Co-Authors: Peter Brodelius, Ana Domingos, M Cordeiro, P Mercke, A Clemente, M S PaisAbstract:Aspartic Proteinases of human, animal, parasite, fungal and retroviral origin have been extensively investigated. The 3-D structures of several such enzymes have been solved and they all have a number of features in common.1 By contrast, relatively little is known about Aspartic Proteinases in plants. During the last few years, however, an increasing number of studies on plant Aspartic Proteinases have been carried out.2,3 We are since a few years involved in studies of milk-clotting enzymes of plant origin.
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substrate specificity and molecular modelling of Aspartic Proteinases cyprosins from flowers of cynara cardunculus subsp flavescens cv cardoon
Advances in Experimental Medicine and Biology, 1998Co-Authors: M Cordeiro, Kunchur Guruprasad, Ben M Dunn, T L Blundell, M S Pais, T Lowther, Peter BrodeliusAbstract:Water extracts of dried flowers of Cynara cardunculus subsp. flavescens cv. cardoon have been traditionally used in Portugal to produce artisanal cheeses (e.g. Serpa and Serra cheeses) with ewe’s milk. The clotting activity is due to three heterodimeric Aspartic Proteinases (cyprosin 1, cyprosin 2 and cyprosin 3) which have been purified from flowers.1 A native Mr of around 49000 was determined for the three cyprosins by SDS-PAGE. The subunit sizes are 32.5 + 16.5, 33.5 + 16.5, and 35.5 + 13.5 kD for cyprosin 1, 2 and 3, respectively. Gel filtration chromatography indicated somewhat lower native Mrs (41–45000). The enzymes are N-glycosylated (high mannose type) and express maximum activity around pH 4.1 using a synthetic peptide as substrate.
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Aspartic Proteinases cyprosins from cynara cardunculus spp flavescens cv cardoon purification characterisation and tissue specific expression
Advances in Experimental Medicine and Biology, 1995Co-Authors: Peter Brodelius, M C Cordeiro, M S PaisAbstract:Flowers of C cardunculus (cardoon) have been used in Portugal since many centuries to make cheese with raw ewe or/and goat milk. Several types of cheeses are well known and highly appreciated for their taste and quality. Examples are Serra, Serpa and Azeitao. The skills of making these artisanal cheeses have been inherited over generations within the same families and are still used today. Farmers collect the mature flowers or upper part of styles during June and July and store them in dry places to be used for clotting of milk during the next seasons, autumn and winter. Traditionally the cheeses are made mainly with fresh ewe’s milk. The Proteinases are extracted from flowers with lukewarm water. This extract is filtered through a cloth which contains a spoon of salt. The milk (2–4 1 per cheese) is also passed through the cloth and then left for coagulation during 30–45 minutes. The whey is removed by collecting the curd in another piece of cloth, and afterwards it is brought into shape with a mold. The ripening period is around 6 weeks at 12°C (room temperature in some regions during winter) in a humid and aerated environment.
T L Blundell - One of the best experts on this subject based on the ideXlab platform.
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substrate specificity and molecular modelling of Aspartic Proteinases cyprosins from flowers of cynara cardunculus subsp flavescens cv cardoon
Advances in Experimental Medicine and Biology, 1998Co-Authors: M Cordeiro, Kunchur Guruprasad, Ben M Dunn, T L Blundell, M S Pais, T Lowther, Peter BrodeliusAbstract:Water extracts of dried flowers of Cynara cardunculus subsp. flavescens cv. cardoon have been traditionally used in Portugal to produce artisanal cheeses (e.g. Serpa and Serra cheeses) with ewe’s milk. The clotting activity is due to three heterodimeric Aspartic Proteinases (cyprosin 1, cyprosin 2 and cyprosin 3) which have been purified from flowers.1 A native Mr of around 49000 was determined for the three cyprosins by SDS-PAGE. The subunit sizes are 32.5 + 16.5, 33.5 + 16.5, and 35.5 + 13.5 kD for cyprosin 1, 2 and 3, respectively. Gel filtration chromatography indicated somewhat lower native Mrs (41–45000). The enzymes are N-glycosylated (high mannose type) and express maximum activity around pH 4.1 using a synthetic peptide as substrate.
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comparative modelling of barley grain Aspartic proteinase a structural rationale for observed hydrolytic specificity
FEBS Letters, 1994Co-Authors: Kunchur Guruprasad, Kirsi Tormakangas, Jukka Kervinen, T L BlundellAbstract:Abstract A model of the barley-grain Aspartic proteinase (HvAP; Hordeum vulgare Aspartic proteinase) has been constructed using the rule-based comparative modelling approach encoded in the COMPOSER suite of computer programs. The model was based on the high resolution crystal structures of six highly homologous Aspartic Proteinases. Results suggest that the overall three-dimensional structure of HvAP (excluding the plant-specific insert; 104 residues in HvAP) is closer to human cathepsin D than other Aspartic Proteinases of known three-dimensional structure. Comparisons of the complexes with the substrate modelled in the active site of HvAP with those of the same substrate modelled in the active site of other Aspartic Proteinases of known three-dimensional structure and specificity, define residues that may influence hydrolytic specificity of the barley enzyme. We have identified residues in the S4 (Ala12), S3 (Gln13, Thr111), S2 (Ala222, Thr287, Met289), S′1 and S′3 (Ile291), S′2 and S′3 (Gln74), S′2 (Arg295), and S′3 (Pro292) pockets, that may account for the observed trends in the kinetic behaviour and specificity when compared to other Aspartic Proteinases. The plant-specific inserted sequence, which may play a role in the transport of HvAP to plant vacuoles (lysosomes), is similar to the saposins and is predicted to be a mixed α-helical and β-strand domain.
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x ray analyses of Aspartic Proteinases v structure and refinement at 2 0 a resolution of the Aspartic proteinase from mucor pusillus
Journal of Molecular Biology, 1993Co-Authors: M Newman, Mohammed O Badasso, Anne Cleasby, S P Wood, F Watson, P Roychowdhury, H B Jones, I J Tickle, T L BlundellAbstract:Abstract The structure of mucor pusillus pepsin (EC 3.4.23.6), the Aspartic proteinase from Mucor pusillus , has been refined to a crystallographic R -factor of 16·2% at 2·0 A resolution. The positions of 2638 protein atoms, 221 solvent atoms and a sulphate ion have been determined with an estimated root-mean-square (r.m.s.) error of 0·15 to 0·20 A. In the final model, the r.m.s. deviation from ideality for bond distances is 0·022 A, and for angle distances it is 0·050 A. Comparison of the overall three-dimensional structure with other Aspartic Proteinases shows that mucor pusillus pepsin is as distant from the other fungal enzymes as it is from those of mammalian origin. Analysis of a rigid body shift of residues 190 to 302 shows that mucor pusillus pepsin displays one of the largest shifts relative to other Aspartic Proteinases (14·4° relative to endothiapepsin) and that changes have occurred at the interface between the two rigid bodies to accommodate this large shift. A new sequence alignment has been obtained on the basis of the three-dimensional structure, enabling the positions of large insertions to be identified. Analysis of secondary structure shows the β-sheet to be well conserved whereas α-helical elements are more variable. A new α-helix h N 4 is formed by a six-residue insertion between positions 131 and 132. Most insertions occur in loop regions: -5 to 1 (five residues relative to porcine pepsin); 115 to 116 (six residues); 186 to 187 (four residues); 263 to 264 (seven residues); 278 to 279 (four residues); and 326 to 332 (six residues). The active site residues are highly conserved in mucor pusillus pepsin; r.m.s. difference with rhizopuspepsin is 0·37 A for 25 C α atom pairs. However, residue 303, which is generally conserved as an aspartate, is changed to an asparagine in mucor pusillus pepsin, possibly influencing pH optimum. Substantial changes have occurred in the substrate binding cleft in the region of S 1 and S 3 due to the insertion between 115 and 116 and the rearrangement of loop 9-13. Residue Asn219 necessitates a shift in position of substrate main-chain atoms to maintain hydrogen bonding pattern. Invariant residues Asp11 and Tyr14 have undergone a major change in conformation apparently due to localized changes in molecular structure. Both these residues have been implicated in zymogen stability and activation.
Euclides Pires - One of the best experts on this subject based on the ideXlab platform.
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the saposin like domain of the plant Aspartic proteinase precursor is a potent inducer of vesicle leakage
Journal of Biological Chemistry, 2000Co-Authors: Conceicao Egas, Euclides Pires, Nuno Lavoura, Rosa Resende, Rui M M Brito, Maria Pedroso C De Lima, Carlos FaroAbstract:Abstract A unique feature of plant Aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH- and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant Aspartic Proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plant-specific insert, alone or in conjunction with the proteolytic activity of plant Aspartic Proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.
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the glycosylation of the Aspartic Proteinases from barley hordeum vulgare l and cardoon cynara cardunculus l
FEBS Journal, 1997Co-Authors: Julia Costa, Carlos Faro, Jukka Kervinen, Euclides Pires, David A Ashford, Manfred Nimtz, Isabel Bento, C Frazao, Cristina Esteves, Paula VerissimoAbstract:Plant Aspartic Proteinases characterised at the molecular level contain one or more consensus N-glycosylation sites [Runeberg-Roos, P., Tormakangas, K. & Ostman, A. (1991) Eur. J. Biochem. 202, 1021–1027; Asakura, T., Watanabe, H., Abe, K. & Arai, S. (1995) Eur. J. Biochem. 232, 77–83; Verissimo, P., Faro, C., Moir, A. J. G., Lin, Y., Tang, J. & Pires, E. (1996) Eur. J. Biochem. 235, 762–7681. We found that the glycosylation sites are occupied for the barley (Hordeum vulgare L.) Aspartic proteinase (Asn333) and the cardoon (Cynara cardunculus L.) Aspartic proteinase, cardosin A (Asn70 and Asn363). The oligosaccharides from each site were released from peptide pools by enzymatic hydrolysis with peptide-N-glycanase A or by hydrazinolysis and their structures were determined by exoglycosidase sequencing combined with matrix-assisted laser desorption/ionization time of flight mass spectrometry. It was observed that 6% of the oligosaccharides from the first glycosylation site of cardosin A are of the oligomannose type. Modified type glycans with proximal Fuc and without Xyl account for about 82%, 14% and 3% of the total oligosaccharides from the first and the second glycosylation sites of cardosin A and from H. vulgare Aspartic proteinase, respectively. Oligosaccharides with Xyl but without proximal Fuc were only detected in the latter proteinase (4%). Glycans with proximal Fuc and Xyl account for 6%, 86% and 92% of the total oligosaccharides from the first and second glycosylation sites of cardosin A and from H. vulgure Aspartic proteinase, respectively.
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action on bovine αs1 casein of cardosins a and b Aspartic Proteinases from the flowers of the cardoon cynara cardunculus l
Biochimica et Biophysica Acta, 1996Co-Authors: Miguel Ramalhosantos, Carlos Faro, Paula Verissimo, Euclides PiresAbstract:The cleavage of purified bovine αs1-casein separately by cardosin A and cardosin B, two distinct milk-clotting Aspartic Proteinases (APs) present in the stigmas of the plant Cynara cardunculus L., was studied. Casein digestion peptides were separated either by SDS-PAGE or by reverse-phase HPLC, and their N-terminal amino-acid sequences were subsequently determined by automated Edman degradation, thus identifying the cleavage sites. Results showed that both enzymes exert a similar but distinct action on bovine αs1-casein. In common they have the preference for the bond Phe23-Phe24, and the cleavage of Trp164-Tyr165 and Phe153-Tyr154. Cardosin A also cleaves the bond Tyr165-Tyr166, whereas Cardosin B cleaves an extra type of bond, Phe150-Arg151, revealing a slightly broader specificity. A model for the action of both enzymes on bovine αs1-casein is proposed and discussed. In comparison with the reported action of chymosin on bovine αs1-casein, both cardosins proved to have a broader specificity towards this particular substrate due to a higher ability to cleave bonds between residues with large hydrophobic side-chains.
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purification characterization and partial amino acid sequencing of two new Aspartic Proteinases from fresh flowers of cynara cardunculus l
FEBS Journal, 1996Co-Authors: Paula Verissimo, Carlos Faro, Arthur J G Moir, Yingzhang Lin, Jordan Tang, Euclides PiresAbstract:Two new Aspartic Proteinases have been isolated from stigmas of the cardoon Cynara cardunculus L. by a two-step purification procedure including extraction at low pH, gel filtration on Superdex 200, and ion-exchange chromatography on Mono Q. To follow the conventional nomenclature for Aspartic Proteinases, we have named these Proteinases cardosin A and cardosin B. On SDS/PAGE, cardosin A migrated as two bands with apparent molecular masses of 31 000 Da and 15000 Da where as the chains of cardosin B migrated as bands of 34000 Da and 14000 Da. The partial amino acid sequences of the two cardosins revealed that they are similar but not identical, and that they differ horn the previously reported cardoon Proteinases named cynarases, which were assumed to be derived from a common precursor. Although the cardosins show some degree of similarity to each other, we could detect no immunological cross-reactivity between them. Both cardosins were active at low pH and were inhibited by pepstatin, with Ki values of 3 nM for cardosin A and 1 nM for cardosin B, indicating that they belong to the class of Aspartic Proteinases. Significant differences between the two enzymes were also found for the Kcat/Km values for the hydrolysis of two chromophoric synthetic peptides. The active-site ionization constants, pKe1 and pKe2, for cardosin A are 2.5±0.2 and 5.3±20.2, whereas for cardosin R they are 3.73±10.09 and 6.7±50.1. The results herein described on the structural and kinetic properties of the cardosins indicate that they are the products of distinct genes which have probably arisen by gene duplication. A scheme for the proteolytic processing of the two enzymes is also proposed.
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cardosin a and b Aspartic proteases from the flowers of cardoon
Advances in Experimental Medicine and Biology, 1995Co-Authors: Carlos Faro, Paula Verissimo, Jordan Tang, Euclides PiresAbstract:Plant Aspartic Proteinases have been detected and purified from several plant monocotyledoneous, dicotyledoneous and gymnosperms. The physiological role of these Aspartic Proteinases is not as yet well elucidated, although the involvement in the hydrolysis of exogenous and storage proteins have been reported (for review see reference 1)
