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Acetonitrile-induced unfolding of porcine pepsin A. Int J Biol Macromol 2009; 45:213-20. [DOI: 10.1016/j.ijbiomac.2009.05.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/12/2009] [Accepted: 05/15/2009] [Indexed: 11/20/2022]
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2
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Cappiello MG, Wu Z, Scott BB, McGeehan GM, Harrison RK. Purification and characterization of recombinant human cathepsin E expressed in human kidney cell line 293. Protein Expr Purif 2005; 37:53-60. [PMID: 15294281 DOI: 10.1016/j.pep.2004.05.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 04/29/2004] [Indexed: 10/26/2022]
Abstract
A cDNA encoding human prepro-cathepsin E was introduced into the adenovirus-transformed HEK-293 (human embryonic kidney) cell line. The construct contained both a V5 peptide epitope and histidine tags at the carboxy terminus. Transfected cells efficiently secreted recombinant pro-cathepsin E into the culture medium. The secreted pro-cathepsin E was purified in a single step using Ni affinity chromatography yielding a protein of about 92 kDa under non-reducing conditions. The amino-terminal sequence of the purified protein began at Ser20, suggesting human cathepsin E accumulated in the culture supernatant as the pro-enzyme. The purified protein was rapidly and completely converted to the active form by treatment at pH 4.0 or below. Steady state kinetic parameters for hydrolysis of the fluorogenic peptide substrate MOCAc-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys(Dnp)-d-Arg-NH2 (cleavage at the Phe-Phe bond) were consistent with previously reported values for purified human enzyme (kc/Ki= 53 x 10(6) M(-1) s(-1), Km= 6.3 microM, and kcat= 3 x 10(2) s(-1)). The activated protein was potently inhibited by pepstatin with Ki= 0.2 nM, as well as a reported beta secretase inhibitor. This work demonstrates the potential for producing large quantities of highly purified human cathepsin E from HEK-293 cells in quantities to support both biochemical and structural characterization of the enzyme.
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Affiliation(s)
- Maria G Cappiello
- Discovery Biology, Concurrent Pharmaceuticals, 502 W Office Center Drive, Fort Washington, PA 19034, USA
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3
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Fuentes ME, Varón R, García-Moreno M, Valero E. Kinetics of autocatalytic zymogen activation measured by a coupled reaction: pepsinogen autoactivation. Biol Chem 2005; 386:689-98. [PMID: 16207090 DOI: 10.1515/bc.2005.080] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A kinetic study was performed of a model for an autocatalytic zymogen activation process involving both intra- and intermolecular routes, to which a chromogenic reaction in which the active enzyme acts upon one of its substrates was coupled to continuously monitor the reaction. Kinetic equations describing the evolution of species involved in the system with time were obtained. These equations are valid for any zymogen autocatalytic activation process under the same initial conditions. Experimental design and kinetic data analysis procedures to evaluate the kinetic parameters, based on the derived kinetic equations, are suggested. In addition, a dimensionless distribution coefficient was defined, which shows mathematically whether the intra- or the intermolecular route prevails once the kinetic parameters involved in the system are known. The validity of the results obtained was checked using simulated curves for the species involved. As an example of application of the method, the system is experimentally illustrated by the continuous monitoring of pepsinogen transformation to pepsin.
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Affiliation(s)
- Matilde-Esther Fuentes
- Grupo de Modelización en Bioquímica, Departamento de Química-Física, Escuela Politécnica Superior de Albacete, Universidad de Castilla-La Mancha, E-02071 Albacete, Spain
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4
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Barros RM, Xavier Malcata F. A kinetic model for hydrolysis of whey proteins by cardosin A extracted from Cynara cardunculus. Food Chem 2004. [DOI: 10.1016/j.foodchem.2004.01.046] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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5
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Barros RM, Malcata FX. Modeling the kinetics of whey protein hydrolysis brought about by enzymes from Cynara cardunculus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:4347-4356. [PMID: 12105969 DOI: 10.1021/jf0200319] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The purpose of this research work was to study the proteolytic activity of aqueous crude extracts of flowers of the plant Cynara cardunculus on the major whey proteins, namely, beta-lactoglobulin (beta-Lg) and alpha-lactalbumin (alpha-La). These extracts, containing a mixture of cardosins A and B (i.e., two distinct aspartic proteases), have been employed for many years in traditional cheese-making in Portugal and Spain. Cow's milk sweet whey was incubated for up to 24 h at various ratios of addition of crude enzyme extract, under controlled pH (5.2 and 6.0) and temperature (55 degrees C). The samples collected were assayed by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A mechanistic model was proposed for the kinetics of the hydrolysis process, which is basically a double-substrate, double-enzyme Michaelis-Menten rate expression; the kinetic parameters were estimated by multiresponse, nonlinear regression analysis. The best estimates obtained for the specificity ratio (i.e., k(cat)/K(m)) of each cardosin within the mixture toward each whey protein indicated that said aspartic proteases possess a higher catalytic efficiency for alpha-La (0.42-4.2 mM(-1).s(-1)) than for beta-Lg (0-0.064 mM(-1).s(-1)), at least under the experimental conditions used. These ratios are below those previously reported for caseins and a synthetic hexapeptide. Cardosins are more active at pH 5.2 than at pH 6.0 and (as expected) at higher enzyme-to-substrate ratios.
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Affiliation(s)
- Rui M Barros
- Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, P-4200-072 Porto, Portugal
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Chitpinityol S, Goode D, Crabbe MC. Site-specific mutations of calf chymosin B which influence milk-clotting activity. Food Chem 1998. [DOI: 10.1016/s0308-8146(97)00204-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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7
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Ramalho-Santos M, Veríssimo P, Faro C, Pires E. Action on bovine alpha s1-casein of cardosins A and B, aspartic proteinases from the flowers of the cardoon Cynara cardunculus L. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1297:83-9. [PMID: 8841384 DOI: 10.1016/0167-4838(96)00103-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The cleavage of purified bovine alpha s1-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 alpha s1-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 alpha s1-casein is proposed and discussed. In comparison with the reported action of chymosin on bovine alpha s1-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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Affiliation(s)
- M Ramalho-Santos
- Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Portugal
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8
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Veríssimo P, Faro C, Moir AJ, Lin Y, Tang J, Pires E. Purification, characterization and partial amino acid sequencing of two new aspartic proteinases from fresh flowers of Cynara cardunculus L. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 235:762-8. [PMID: 8654427 DOI: 10.1111/j.1432-1033.1996.00762.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
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 15 000 Da whereas the chains of cardosin B migrated as bands of 34 000 Da and 14 000 Da. The partial amino acid sequences of the two cardosin revealed that they are similar but not identical, and that they differ from 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 crossreactivity 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+/- 0.2, whereas for cardosin B they are 3.73 +/- 0.09 and 6.7 +/- 0.1. 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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Affiliation(s)
- P Veríssimo
- Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Portugal
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McMahon EG, Yang PC, Babler MA, Bittner SE, Suleymanov OD, Cain-Janicki KJ, Bedell LJ, Hanson GJ, Cook CS. Effects of SC-56525, a potent, orally active renin inhibitor, in salt-depleted and renal hypertensive dogs. Hypertension 1995; 26:95-100. [PMID: 7607739 DOI: 10.1161/01.hyp.26.1.95] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
SC-56525 is a nanomolar inhibitor of plasma renin activity in human, cynomolgus monkey, dog, guinea pig, Yucatan micropig, and rabbit but is less active in rat. The oral bioavailability of SC-56525 in conscious dogs at doses of 5 mg/kg IV and 30 mg/kg PO was 66.1 +/- 16.4%. Oral dosing with SC-56525 at 3, 10, and 30 mg/kg in salt-depleted dogs induced a dose-dependent reduction in mean arterial pressure and inhibition of plasma renin activity with no significant effect on heart rate. In two-kidney, one clip renal hypertensive dogs, SC-56525 given orally at 10, 30, and 60 mg/kg daily for 4 days lowered blood pressure significantly. In conscious dogs monitored in their home cages via radiotelemetry, no significant changes in heart rate occurred in response to large drops in blood pressure in both renal hypertensive and salt-depleted dogs with the renin inhibitor SC-56525. SC-56525 is a nanomolar, orally active inhibitor of renin and effectively lowers blood pressure in both salt-depleted and renal hypertensive dogs.
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Faro C, Verissimo P, Lin Y, Tang J, Pires E. Cardosin A and B, aspartic proteases from the flowers of cardoon. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 362:373-7. [PMID: 8540346 DOI: 10.1007/978-1-4615-1871-6_49] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- C Faro
- Departamento de Bioquímica, Universidad de Coimbra, Portugal
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11
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Schnaith E. Determination of the pepsin activity in human gastric juice, using defined oligopeptides as substrates. Clin Biochem 1989; 22:91-8. [PMID: 2498014 DOI: 10.1016/s0009-9120(89)80004-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Different methods for the determination of pepsin activity in human gastric juice, using defined oligopeptides as substrates, were investigated. N-Acetyl-L-phenylalanyl-L-3,5-diiodotyrosine and tripeptides like benzyloxycarbonyl-L-histidyl-L-phenylalanyl-L-tryptophan ethyl ester, benzyloxycarbonyl-L-histidyl-L-phenylalanyl-L-tyrosine ethyl ester, or benzyloxycarbonyl-L-histidyl-L-4-nitrophenylalanyl-L-phenylalanine methyl ester lead to only small absorption changes in the direct measurement of pepsin activity. Suitable substrates were shown to be the hexapeptide, L-leucyl-L-seryl-L-4-nitrophenylalanyl-L-norleucyl-L-alanyl-L- leucine-methyl ester and the octapeptide, L-prolyl-L-histidyl-L-leucyl-L-seryl-L-4-nitrophenylalanyl-L-norleucyl-L -alanyl-L-leucine methyl ester. Hydrolysis of these peptides can be measured continuously, using a spectral line photometer at 313 nm. Optimal test conditions and kinetic constants for substrate cleavage by pepsin in solution and by human gastric juice were determined.
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Affiliation(s)
- E Schnaith
- Zentralinstitut für Klinische Chemie, der Universität Düsseldorf, FRG
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Pohl J, Dunn BM. Secondary enzyme-substrate interactions: kinetic evidence for ionic interactions between substrate side chains and the pepsin active site. Biochemistry 1988; 27:4827-34. [PMID: 3139029 DOI: 10.1021/bi00413a037] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The possibility that pig pepsin has a cation binding specificity in its secondary binding subsites has been examined by the pepsin-catalyzed hydrolysis of a series of synthetic octa- to undecapeptide substrates. These chromophoric substrates are cleaved by pepsin in the phenylalanyl-p-nitrophenylalanyl (Phe-Nph) bond. Lys and Arg residues were placed into seven different positions in the substrates, and their effect on kcat and Km was examined between pH 2.8 and pH 5.8 (I = 0.1 M, 37 degrees C). Kinetic evidence indicates the existence in the enzyme binding subsites S4, S3, S2, S3', S4', and S5' of a group(s) which become(s) negatively charged at higher pH. For most substrates, the magnitude as well as the pH dependence of kcat was unaffected by the presence of Lys or Arg in these peptides. In contrast, changes up to 5 orders of magnitude were observed for Km, depending on the number of basic residues and on their positions in the sequence. Km for a group of substrates at pH greater than 5.5 was lower than 50 nM. Values for kcat/Km for some substrates exceed the level of 10(8) M-1 s-1. Therefore, the free energy derived from ionic interactions in secondary binding sites influences mostly the binding step on the reaction pathway. This result is in contrast to the previous observations that the length and the hydrophobic character of the substrate residues in some positions influence kcat with little effect on Km toward shorter substrates of pepsin [Fruton, J. (1976) Adv. Enzymol. Relat. Areas Mol. Biol. 44, 1-36].
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Affiliation(s)
- J Pohl
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville 32610
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Guerard F, Le Gal Y. Characterization of a chymosin-like pepsin from the dogfish Scyliorhinus canicula. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1987; 88:823-7. [PMID: 3123128 DOI: 10.1016/0305-0491(87)90250-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. Pepsin II extracted from the gastric mucosa of Scyliorhinus canicula has been characterized and compared to calf chymosin. 2. The kcat and Km of the dogfish enzyme for the synthetic hexapeptide Leu-Ser-Phe(NO2)-Nle-Ala-Leu-OMe have been determined. The kcat/Km ratio is close to that of calf chymosin. Its milk-clotting efficiency is however 21-fold lower than that of calf chymosin. 3. The proteolytic activity against haemoglobin is optimal at pH 2.5. It clots the milk up to pH 6.8. 4. The dogfish pepsin II shows relatively better activity at low temperatures than calf chymosin.
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Affiliation(s)
- F Guerard
- Laboratory of Marine Biology, Collège de France, Finistere
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Dunn BM, Jimenez M, Parten BF, Valler MJ, Rolph CE, Kay J. A systematic series of synthetic chromophoric substrates for aspartic proteinases. Biochem J 1986; 237:899-906. [PMID: 3541904 PMCID: PMC1147073 DOI: 10.1042/bj2370899] [Citation(s) in RCA: 143] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The hydrolysis of the chromogenic peptide Pro-Thr-Glu-Phe-Phe(4-NO2)-Arg-Leu at the Phe-Phe(4-NO2) bond by nine aspartic proteinases of animal origin and seven enzymes from micro-organisms is described [Phe(4-NO2) is p-nitro-L-phenylalanine]. A further series of six peptides was synthesized in which the residue in the P3 position was systematically varied from hydrophobic to hydrophilic. The Phe-Phe(4-NO2) bond was established as the only peptide bond cleaved, and kinetic constants were obtained for the hydrolysis of these peptide substrates by a representative selection of aspartic proteinases of animal and microbial origin. The value of these water-soluble substrates for structure-function investigations is discussed.
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