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PubMed2003

Selective disruption of lysosomes in HeLa cells triggers apoptosis mediated by cleavage of Bid by multiple papain-like lysosomal cathepsins.

Increasing evidence suggests that lysosomal proteases are actively involved in apoptosis. Using HeLa cells as the model system, we show that selective lysosome disruption with L-leucyl-L-leucine methyl ester results in apoptosis, characterized by translocation of lysosomal proteases into the cytosol and by the cleavage of a proapoptotic Bcl-2-family member Bid. Apoptosis and Bid cleavage, but not translocation of lysosomal proteases to the cytosol, could be prevented by 15 microM L-trans-epoxysuccinyl(OEt)-Leu-3-methylbutylamide, an inhibitor of papain-like cysteine proteases. Incubation of cells with 15 microM N-benzoyloxycarbonyl-VAD-fluoromethyl ketone prevented apoptosis but not Bid cleavage, suggesting that cathepsin-mediated apoptosis in this system is caspase-dependent. In vitro experiments performed at neutral pH showed that papain-like cathepsins B, H, L, S, and K cleave Bid predominantly at Arg(65) or Arg(71). No Bid cleavage was observed with cathepsins C and X or the aspartic protease cathepsin D. Incubation of full-length Bid treated with cathepsins B, H, L, and S resulted in rapid cytochrome c release from isolated mitochondria. Thus, Bid may be an important mediator of apoptosis induced by lysosomal disruption.

Animals↗

PubMed2001

Papain does not cleave operator-bound lambda repressor: structural characterization of the carboxy terminal domain and the hinge.

The circular dichroism spectra of three different purified carboxy terminal fragments 93-236, 112-236 and 132-236 of the bacteriophage lambda cI repressor have been measured and compared with those of the intact repressor and the amino terminal fragment 1-92. All three carboxy terminal fragments contain mostly beta-strands and loops, a minor helix content increasing with the size of the fragment, showing that the 93-131 region previously called a hinge is structured. Fourier transformed infrared spectra also showed that fragment 93-236 contains alpha-helices, alpha-sheets and turns but fragment 132-236 contains no detectable alpha-helix, only beta-sheets and turns. Papain is known to cleave the lambda repressor, but it is shown here that it cannot cleave the operator-bound repressor dimer. For the 132-236 fragment, both the wt and the SN228 mutant previously shown to be dimerization defective in the intact, gave similar dimerization properties as investigated by HPLC at 2 to 100 microM protein concentration, with a KD of 13.2 microM and 19.1 microM respectively. The papain cleavage for wt and SN228 proceed at equal rates for the first cleavage at 92-93; however, the subsequent cleavages are faster for SN228. The three Cys residues in the 132-236 fragment were found to be unreactive upon incubation with DTNB, indicating the thiol sulfur atoms are buried in the repressor carboxy terminal domain. Denaturation of the 132-236 fragment studied by tryptophan fluorescence shows two transitions centered at 1.5 M and 4.5 M of urea.

Circular Dichroism↗

PubMed1984

The inactivation of papain by high LET radiations.

The effect of varying LET over a wide range (0.2-1570 eV/nm) on the radiation-induced inactivation of the enzyme papain in dilute aqueous solution has been investigated. Measurements of total, reparable and non-reparable inactivation G values in oxygen, nitrous oxide and argon saturated solutions have allowed the contributions to inactivation from radicals and hydrogen peroxide to be evaluated. At high LET the results demonstrate an increasing component due to reaction of the superoxide radical, formed from oxygen produced in the track as a primary radiolysis product. This effect was not observed in our previous study with ribonuclease due to the insensitivity of ribonuclease to inactivation by superoxide and hydrogen peroxide. The results obtained with papain clearly demonstrate a maximum in G (H2O2) at an LET of approximately 140 eV/nm. Generation of O2 within the track as a primary radiolysis product at high LET now appears to be confirmed as an important mechanism leading to reduction in the oxygen enhancement ratio for cellular systems exposed to high LET radiations (Baverstock and Burns 1981).

Energy Transfer↗

PubMed1998

Cys25-nitrosylation inactivates papain.

Nitric oxide (NO) may modulate the catalytic activity of cysteine proteases. In the present study, the inhibitory effect of NO, released by the NO-donors (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide and nitroprusside, on papain action is reported. Papain inactivation via NO-mediated nitrosylation of the Cys25 catalytic residue represents a molecular model for cysteine protease inhibition.

Cysteine↗

PubMed1958

Papain-induced changes in rabbit cartilage; alterations in the chemical structure of the cartilage matrix.

Some biochemical aspects of the collapse of the rabbit ears produced by the intravenous injection of papain have been studied. A marked depletion of chondromucoprotein (M.C.S.) and a reduction of the S(35) content of cartilage matrix were found to coincide with the gross and histologic changes in the cartilage. At the same time there was a marked increase in the amount of S(35) in the serum and an increase of S(35) and glucuronic acid excreted in the urine. Alteration in the composition of the M.C.S. remaining in the cartilage of the papain-injected animals was detected. The findings indicate that the collapse of the rabbit ears is due to loss of chondromucoprotein from cartilage and reduction of chondroitin sulfate in the chondromucoprotein that remains. All these changes were reversed in recovery.

Animals↗

PubMed1960

Comparison of the effects of papain n vitamin A on cartilage. I. The effects in rabbits.

The administration of large amounts of vitamin A to rabbits has been shown to result in depletion of cartilage matrix. The normal basophilic, metachromatic, and Alcian blue staining properties of the matrix are lost, especially in articular and epiphyseal cartilage. The cartilage cells remain intact, but are reduced in size. These changes sometimes appeared as early as 48 hours after the initiation of daily injection of 1 million units of vitamin A, and were usually well established by 5 days. Some rabbits failed to show changes in cartilage, even after 5 daily injections. Increased amounts of material presumed to be chondroitin sulfate were present in the sera of vitamin A-treated rabbits, usually by 72 hours after the first injection. This was demonstrated by a turbidimetric procedure using hexamminecobaltic chloride. In rabbits given sulfur-35 (Na(2)S(35)O(4)) 5 days before the initiation of vitamin A treatment, it was shown that sulfur-35 was lost from articular and epiphyseal cartilage. This was associated with an increase in the non-dialyzable sulfur-35 in both serum and in the cobalt-precipitable material. These rabbits also excreted more sulfur-35 than rabbits not given vitamin A. There was a reduction in sulfur-35 activity in chondromucoprotein extracted from the ear cartilage of vitamin A-treated rabbits. The changes are interpreted as indicating that the administration of large amounts of vitamin A to rabbits results in removal of chondroitin sulfate from cartilage matrix. The administration of small amounts of crude papain causes histologic changes in cartilage that are remarkably similar to those seen in vitamin A-treated rabbits. The possibility is suggested that the changes in cartilage produced by administration of vitamin A to rabbits may be the result of activation of a proteolytic enzyme or enzymes, with properties similar to those of papain.

Animals↗

PubMed1960

Increased fixation of sulfur-35 by cartilage in vitro following depletion of the matrix by intravenous papain.

The uptake in vitro of sulfur-35 by costal cartilage obtained from nine rabbits 11 days after an intravenous injection of crude papain solution was compared with that in costal cartilage from eight normal untreated rabbits. An increased fixation of the isotope was found in treated animals compared with controls. The depletion of cartilage matrix by papain provided an experimental situation to test the hypothesis that the depletion of matrix which occurs in osteoarthritic cartilage can stimulate increased synthesis of chondroitin sulfate. The results give further support to the view that the primary lesion in osteoarthritis occurs in the matrix rather than in the chondrocyte of articular cartilage.

Animals↗

PubMed1969

Ultrastructure of papain and pepsin digestion fragments of human IgM globulins.

The ultrastructure of papain and pepsin-digested products of human IgM globulins has been analyzed. Papain digestion was performed both in the presence and absence of cysteine. The Fcmicro fragment was found to represent the central ring structure in the intact IgM molecule, plus a minor part of the appendages extending from the ring. The Fcmicro ring structure was occasionally seen to be composed of dimers of short rods, probably identical with the endpieces of two micro-chains. Such dimeric structures, released from the intact Fcmicro rings, had a tendency to aggregate sidewise, producing complexes of varying size. The dimensions of the Fcmicro fragments were: outer diameter approximately 85 A, inner diameter about 40 A. The length of the protrusions varied from 20-30 A. The Fabmicro preparations contained long strands of sidewise aggregated, short rod-shaped fragments. No aggregates were seen in the F(ab'')(2)micro preparations. The two Fab''micro units in the dimeric F(ab'')(2)micro fragments were usually parallel to each other. The dimensions of the Fabmicro and F(ab'')(2)micro fragments were 50-80 A x 30 A and 75-80 A x 55 A, respectively. These findings provide morphological evidence that the C-terminal ends of the micro-chains (the Fcmicro fragment) make up the central ring structure in the IgM molecule. They further indicate that the F(ab'')(2)micro fragments constitute about (3/4) of the appendages extending from this ring structure.

Binding Sites↗

PubMed1982

Antigen-specific T lymphocyte clones. III. Papain splits purified T suppressor molecules into two functional domains.

Purified molecules (70,000 mol wt) from a T-suppressor (Ts) clone bind to sheep erythrocyte glycophorin and specifically suppress the response to this antigen. Papain splits purified 70,000-mol wt Ts molecules into two peptides: mol wt 45,000 and 24,000. The 45,000-mol wt peptide nonspecifically suppresses antibody response to several antigens and lacks antigen-binding activity. The 24,000-mol wt peptide does not suppress but retains antigen-binding activity. The results indicate that papain splits the Ts molecule into a "constant" region responsible for function and a "variable" region responsible for antigen-binding. Since binding of the 70,000-mol wt molecule to antigen also results in release of the 45,000 mol wt subunit, this cleavage may allow Ts molecules specific for one determinant to suppress immunity to complex foreign proteins.

Animals↗

PubMed1987

A new protocol to digest human IgM with papain that results in homogeneous Fab preparations that can be routinely crystallized.

A method has been developed for the routine production of Fab fragments from human IgM in high yield. After the IgM is purified at physiological pH, it is digested with papain in the presence of cysteine at room temperature for 16 hours. The Fab fragments are purified initially by gel filtration and then by ion exchange chromatography. The yield of Fab has been 60-80%. Some heterogeneity in the size of the Fabs from the different monoclonal IgMs has been observed. Fab fragments from four different IgM rheumatoid factors (RF) have been crystallized after such digestion and purification, in a variety of conditions including phosphate buffer alone or with the precipitating agents ammonium sulfate, polyethylene glycol or methylpentanediol. This modified papain digestion method has also been used for another non-RF monoclonal human IgM with equally good yield. Biological activity can be detected in the purified Fab fragment indicating that this procedure does not destroy the native conformation of the molecule.

Amino Acid Sequence↗

PubMed1998

Structure of the foot-and-mouth disease virus leader protease: a papain-like fold adapted for self-processing and eIF4G recognition.

The leader protease of foot-and-mouth disease virus, as well as cleaving itself from the nascent viral polyprotein, disables host cell protein synthesis by specific proteolysis of a cellular protein: the eukaryotic initiation factor 4G (eIF4G). The crystal structure of the leader protease presented here comprises a globular catalytic domain reminiscent of that of cysteine proteases of the papain superfamily, and a flexible C-terminal extension found intruding into the substrate-binding site of an adjacent molecule. Nevertheless, the relative disposition of this extension and the globular domain to each other supports intramolecular self-processing. The different sequences of the two substrates cleaved during viral replication, the viral polyprotein (at LysLeuLys/GlyAlaGly) and eIF4G (at AsnLeuGly/ArgThrThr), appear to be recognized by distinct features in a narrow, negatively charged groove traversing the active centre. The structure illustrates how the prototype papain fold has been adapted to the requirements of an RNA virus. Thus, the protein scaffold has been reduced to a minimum core domain, with the active site being modified to increase specificity. Furthermore, surface features have been developed which enable C-terminal self-processing from the viral polyprotein.

Amino Acid Sequence↗

PubMed1976

Cell-mediated immunity in mice against papain-solubilized histocompatibility and tumor-specific antigens by a macrophage migration inhibition microassay.

The cell-mediated immune status of B10.D2 (H-2d) mice immunized with spleen cells from a congenic strain, B10.A (H-2a), differing at the H-2 locus and of BALB/c mice immunized with a syngeneic simian virus 40 (SV40)-induced sarcoma (mKSA-TU5) was evaluated by an agarose microassay for migration inhibition factor. The inducing antigens in this experiment were papain-solubilized and partially purified chromatographic preparations of spleen cells from A/J mice (H-2a) and a papain-solubilized antigen extract prepared from a tissue culture-adapted cell line (TU-5), derived from the SV40-induced mKSA tumor. The assay used microliters of normal or immune peritoneal exudate cells (PEC) resuspended in a 2-mul droplet of agarose and cultured in the presence or absence of antigen. Specific migration inhibition of PEC from immunized mice was observed with concentrations of solubilized antigen preparations as low as 2.0 mug/ml (3.67 mug/chamber).

Animals↗

PubMed1987

Comparative study on the active sites of ficin and papain by the spin labeling method.

Ficin was alkylated with a series of haloacetamide spin labels with various distances between the spin probes and reactive groups. From the relation of these distances to the tau c values of the labels incorporated into protein, it was estimated that the depth of the active site hole of ficin is ca. 8 A. The results are somewhat different from those reported previously for papain (S. Nakayama et al. (1981) Biochem. Biophys. Res. Commun. 98, 471-475). Examination of the pH dependence of the ESR spectra for ficin and papain alkylated with an iodoacetamide or a maleimide spin label suggested that these enzymes have an amino acid residue of pKa 4 (probably a histidine residue) around the active site cysteine and that the active site conformations change at around pH 5.

Binding Sites↗

PubMed1975

Photooxidation of histidine and tryptophan residues of papain in the presence of methylene blue.

Papain [EC 3.4.22.2] was photooxidized using methylene blue as a sensitizer. The photooxidzed enzyme lost its caseinolytic activity and had significantly decreased histidine and tryptophan contents. The tyrosine content was the same before and after the photooxidation. The SH content of the photooxidized enzyme, as determined after reduction with dithiothreitol, was also unchanged. The loss of histidine was always slower than the loss of enzymatic activity, being less than one residue per molecule even when the enzymatic activity was completely lost. However, the inactivation and the oxidation of a histidine residue were pH-dependent in a similar fashion in the pH range of 5.0-8.0, the pH profiles conforming to theoretical titration curves with apparent pKa values of 6.6 and 6.7, respectively. The fact that the ionization of a histidine residue in papain has a normal imidazole pKa value is entirely in accord with the finding for stem bromelain [EC 3.4.22.4] (Murachi, T., Tsudzuki, T., & Okumura, K. (1975) Biochemistry 14, 249-255), and is of great significance in relation to the mechanism of catalysis by these enzymes.

Amino Acids↗

PubMed1981

Peptide bond synthesis catalyzed by subtilisin, papain, and pepsin.

The peptide bond syntheses catalyzed by subtilisin BPN', papain [EC 3.4.22.2], and pepsin [EC 3.4.23.1] were studied comparatively at the optimum pH of the enzymes with the coupling system Cbz-(AA)n-OH + Leu-X leads to Cbz-(AA)n-Leu-X, in which AA = various amino acid residues, n = 1-3 and X = -NH2, -OEt, -OBut, -ODPM (diphenyl methyl ester) or -NH. The coupling with these enzymes differed depending upon the nature of (AA)n and X. For subtilisin-catalyzed coupling, the molecular size of the carboxyl component was most important. Thus, Cbz-Gly-Pro-Leu-OH was useful for synthesis in the presence of an equimolar concentration of Leu-NH. Either Ala-NH2 or Leu-NH2 was also useful as an amine component when present at a concentration several times that of the carboxyl component. Papain catalyzed the coupling between Cbz-AA-OH (AA = glycine, L-alanine, L-valine, L-glutamic acid, or L-phenylalanine) and Leu-X (X = -OBut and -ODPM). The coupling of Cbz-Gly-Phe-OH and Leu-X catalyzed by pepsin was markedly affected, depending upon the nature of X in the following order: -NH greater than -OBut greater than -NH2, -OEt. Leu-NH2, however, was quite efficient when its molar concentration was raised to twenty times that of the carboxyl component.

Hydrogen-Ion Concentration↗

PubMed1981

Papain inhibitions by optically active E-64 analogs.

Modification of E-64 focused on the terminal agmatine for practical use led to some potent analogs which were successfully obtained by a stereoselective synthesis using D-tartaric acid as a starting material. Ep-475 (id. E-64-c), in which the agmatine was replaced by 3-methyl-butylamine, was found to react with the essential SH of papain in accord with the decrease of activity. [3H]Ep-475 was irreversibly incorporated into papain in an equimolar ratio. None of the analogs showed any effect on thiol enzymes other than proteolytic ones.

Agmatine↗

PubMed1984

Partial purification and some properties of a new papain inhibitor from psoriatic scales.

A new papain inhibitor was purified from psoriatic epidermal scales using gel chromatography and anion exchange chromatography. The purified protein inhibited papain and ficin but not cathepsin B, cathepsin H, trypsin, or chymotrypsin. Isoelectric focusing revealed 3 major inhibitor variants with pI's of 7.3, 6.9, and 6.5. A Mr of 38,000 was obtained by a gel chromatographic method for the crude inhibitor. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis the Mr values of the isoelectric variants were: 43,000 for the variant pI 7.3, 43,000 and 35,000 for the variant pI 6.9, and 34,000-35,000 for the variant pI 6.5. An antiserum of the inhibitor was used to locate the inhibitor in the psoriatic and normal epidermis. In psoriatic epidermis, the inhibitor was found in the peripheral cytoplasm of spinous cells and in the scale. In normal epidermis, the staining was seen only in orifices of hair follicles. An inhibitor with similar size and antigenic properties to that isolated from the psoriatic scales was demonstrated in extracts made from the whole-thickness epidermis but not in extracts from the healthy epidermal scales, the dermis, the liver, the spleen, or the blood serum.

Cadaver↗

PubMed1990

Thio-alpha-amino acids (S-acids) as a carboxyl component in peptide synthesis catalysed by papain.

Peptide synthesis catalysed by papain was studied using thio-alpha-amino acids (S-acids) as a carboxyl component. It was found, for example, that with Z-AlaSH (pK 2.70) the maximal yield of the peptide Z-AlaValNH2 was obtained at pH 8-8.5. A two-fold excess of Z-AlaSH furnished peptides with yields close to 100%. Thio-amino acids with bulky side groups, for example, Z-IleSH, Z-Asp(OBu')SH, gave peptides with a low yield. Papain interacts with Z-AlaSH better than do bromelain or ficin.

Amino Acid Sequence↗