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PubMed1978

Rate constants of individual steps in papain-catalysed reactions.

Rate constants for acylation of papain (EC 3.4.22.2) by specific substrates and its subsequent deacylation are derived from kinetic analysis of the reactions in the presence of aminoacetonitrile and methanol. Methyl and ethyl hippurate and methyl N-benzyloxycarbonylglycinate have marginally higher values of rate constants for acylation than for deacylation, while the reverse is true for ethyl N-benzoyl-L-arginate. Both acylation and deacylation are rate-determining for these substrates, while only deacylation irate-determining for methyl-N-acetyl-L-phenylalanylglycinate. Deacylation is the only rate-determining step for p-nitrophenyl esters of hippuric acid, N-benzyloxycarbonylglycine and N-acetyl-L-phenylalanylglycine. These results are discussed in relation to those from inactivation of the enzyme by alkylating agent in the presence of substrate.

Kinetics↗
PubMed1981

Papain-derived fragment IIc of tetanus toxin: its binding to isolated synaptic membranes and retrograde axonal transport.

The papain-derived fragment IIc of tetanus toxin, which is immunologically identical to the B-IIb fragment, has previously been shown to bind gangliosides. As could be expected from its analogy with the B-IIb fragment, the IIc fragment was also found to bind to isolated synaptic membranes and to be transported retrogradely from the axonal endings within muscle to the motoneuronal perikarya. It is concluded that the IIc fragment--like the B-IIb fragment--might also serve as a specific carrier for chemical and chemotherapeutical agents into the central nervous system.

Afferent Pathways↗
PubMed1985

Effect of papain digestion on redox-linked proton translocation in b-c1 complex from beef heart reconstituted into liposomes.

Papain treatment of the cytochrome b-c1 complex from beef heart results in partial proteolysis of core protein II, the iron-sulphur protein and the 15-kDa subunit. Under these conditions a significant inhibition of electron flow and complete suppression of proton translocation in the complex reconstituted into liposomes are observed. Kinetic experiments indicate a correlation between the digestion of core protein II and 15-kDa subunit and the suppression of proton translocation. The results suggest an active involvement of polypeptides of the complex in stabilizing the semiquinone species and/or providing pathways to exchange protons between bound quinone systems and aqueous phases.

Animals↗
PubMed1986

Domain structure of human alpha 2-macroglobulin. Characterization of a receptor-binding domain obtained by digestion with papain.

Digestion of methylamine-treated alpha 2-macroglobulin (alpha 2M X MA) with catalytic amounts of papain at pH 4.5 has been investigated. Cleavage of Lys(1313)-Glu resulted in two major products, which could be separated by gel chromatography: a large disulfide bridged fragment set nearly the size of intact alpha 2M X MA, and an 18 kDa fragment, constituting the carboxy-terminal domain of alpha 2M. This domain contained the receptor recognition site, exposed as a result of cleavage of the internal beta-cysteinyl-gamma-glutamyl thiol esters in alpha 2M. Compared with alpha 2M-trypsin complex the apparent affinity for binding to rat hepatocyte receptors was 0.1 and 2% at 4 and 37 degrees C, respectively. The receptor-binding domain presumably forms a compact globular beta-barrel-type structure, stable at pH 2.5-9.0. Chemical modification experiments suggest that receptor binding is contributed by a determinant formed by the precise folding of the polypeptide chain.

Animals↗
PubMed1975

Increased affinity of guinea pig thymocytes and thymus-dependent lymphocytes for papain-treated rabbit erythrocytes compared to untreated erythrocytes.

The affinity of guinea pig thymocytes and peripheral T lymphocytes for rabbit erythrocytes was found to be enhanced following treatment of the erythrocytes with papain. By increasing the numbers of rosette-forming cells and giving stronger, more stable rosettes, this procedure increases the usefulness of the reaction as a T cell marker in guinea pigs.

Animals↗
PubMed1981

Isolation of a papain-solubilised major transplantation antigen from rat leukaemic cells.

The major transplantation antigen of the PVG rat, Rt-1c, has been isolated from PVG leukaemic cells in milligram quantities for use in biological experiments related to transplantation. A 3-stage isolation procedure was developed involving the preparation of plasma membranes, digestion of the membranes with papain to release an active fragment of the Rt-1c antigen and fractionation of the digest on Sephacryl columns to give an active product. Activity was followed by a newly developed inhibition assay in which extracts of cells were incubated with a reference anti-PVG antiserum, excess unreacted antibody being quantitated by radioactive binding to PVG leukaemic cells glutaraldehyde-fixed to flexible microtitre plates. In addition to Rt-1c the preparation contained a second glycoprotein component. The preparation shows allelic specificity in that it inhibits the binding of anti-PVG antiserum to PVG cells, but not the binding of anti-DA serum to DA cells. The preparation represents a 16% yield of the activity of the cells from which it was derived.

Animals↗
PubMed1986

Efficiency of papain-treated microfilariae of Wuchereria bancrofti (var. pacifica) as antigen for serodiagnosis of bancroftian filariasis in French Polynesia.

Papain-treated microfilariae of Wuchereria bancrofti have been used as antigen for indirect fluorescent assay: 0% of non-endemic sera, 8% of healthy exposed Polynesians, 48% of clinical patients and 96% of microfilaraemic subjects were positive by this test. The geometric mean titres were 22, 41, 147 and 605 respectively. Untreated microfilariae were unsuitable for diagnostic purposes. Dirofilaria immitis adult sections showed low reactivity, giving poor discrimination between non-endemic and microfilaraemic sera. The geometric mean titres were 6 and 61 respectively.

Antigens, Helminth↗
PubMed1977

Amphibian embryo protease inhibitors. IV. Studies on an inhibitor of chymotrypsin and papain.

Amphibian embryo chymotrypsin and papain inhibitor (ACPI) purified by the procedure described in this paper produces a single band on sodium dodecyl sulfate (SDS) gel electrophoresis and a single peak on Sephadex G-75 chromatography. Except for its enzyme specificity, ACPI is very similar to amphibian embryo trypsin inhibitor (ATI). Its molecular weight is about 10,500 and its amino acid composition is typical of many naturally occurring protease inhibitors. Inhibition develops slowly, is retarded by the presence of substrate and is temporary. ACPI is localized in the yolk platelets and its disappearance both from whole embryos and from select tissue types corresponds closely with that of ATI. Possible roles for amphibian embryo proteases and protease inhibitors in development are discussed.

Animals↗
PubMed1988

Improvement of a procedure for preparing single smooth muscle cells from guinea pig tenia coli by purified collagenase and papain.

Procedures for isolating single smooth muscle cells from tenia coli of guinea pigs have been developed. The cells were isolated with a combination of highly purified collagenase and a small amount of strong peptidase, papain, in the presence of Ca. This combination resulted in approximately a 100-fold yield of the single cells as compared with the ordinary method in which only collagenase preparations contaminated with various peptidases were used. More than 95% of the single cells were viable when examined by the trypan blue exclusion technique. In addition, this combination greatly increased the responsiveness to agonists such as carbachol (CCh). A concentration of CCh for the half maximum response for this preparation was about one five-hundredth that of cells prepared by the ordinary method. This value was approximately one-quarter that of intact tissue. This preparation can be used to investigate the physiology, pharmacology, and biochemistry of smooth muscle.

Animals↗
PubMedDate not supplied

Direct production of Fv-fragments from a family of monoclonal IgGs papain digestion.

Fv fragments of four monoclonal antibodies specific for morphine binding have been produced from their divalent IgG forms by papain digestion using the classic procedure for Fab formation. The binding characteristics of one of the Fv fragments have been determined relative to the intact antibody by equilibrium dialysis. Its dissociation constant is a factor of five lower than the IgG. Previous work had resulted in the sequences of each the chains for the four Fv fragments. The light chains are all from the highly homologous lambda subclass while the gamma heavy chains are closely related except for their CDR regions. In this work optical molar extinction coefficients are predicted from amino acid sequences for each of the fragments. It is found that they differ significantly from each other and from the commonly used value for intact IgG. Detailed comparisons between our results and those reported previously on the molecular masses of Fv-derived light and heavy chains and hapten-Fv dissociation constants are given based on analytical gel electrophoresis and electroblotting experiments using dye and immunovisualization techniques. Isoelectric focusing experiments have been performed and the pIs obtained are compared to those predicted theoretically from the chain sequences. Gel filtration column chromatography, acrylamide gel electrophoresis and equilibrium dialysis experiments are consistent with significant aggregation of the Fv fragments in neutral solution with accompanying inactivation of the binding site. Comparison of sequences for the Fv light and heavy chains are made with those which have been proposed to be important for chain dimer association and for canonical hypervariable regions. This methods of Fv production is not regarded as a general one. However, it may be an approach which is general to lambda chain containing antibodies.

Animals↗
PubMed1990

The structure-activity relationship of the papain hydrolysis of N-benzoylglycine esters.

The relationship between structure and the Michaelis-Menten constants (Km) for the papain hydrolysis of a series of 37 N-benzoylglycine esters was investigated. The series studied comprises a wide range of aromatic and aliphatic esters with a 5000-fold variation in their Km constants and essentially constant kcat values. It was found that the variation in the Km constants could be rationalized by the following quantitative structure-activity relationship (QSAR): log 1/Km = 8.13F + 0.33Z + 1.27II3' + 1.95. In this equation F is the field inductive parameter, II3' is the hydrophobic constant for the more lipophilic of the two possible meta substituents and Z is the Van der Waals distance from oxygen through the end of the molecule, in the direction of the 4 position of the aromatic ester moiety.

Computer Simulation↗
PubMed1991

Separation of electronic and hydrophobic effects for the papain hydrolysis of substituted N-benzoylglycine esters.

The role of hydrophobic and electronic effects on the kinetic constants kcat and Km for the papain hydrolysis of a series of 22 substituted N-benzoylglycine pyridyl esters was investigated. The series studied comprises a wide variety of substituents on the N-benzoyl ring, with about a 300,000-fold range in their hydrophobicities, and 2.1-fold range in their electronic Hammet constants (sigma). It was found that the variation in the log kcat and log 1/Km constants could be explained by the following quantitative-structure activity relationships (QSAR): log 1/Km = 0.40 pi 4 + 4.40 and log 1/kcat = 0.45 sigma + 0.18. The substituent constant, pi 4, is the hydrophobic parameter for the 4-N-benzoyl substituents. QSAR analysis of two smaller sets of glycine phenyl and methyl esters produced similar results. A clear separation of the substituent effects indicates that in the case of these particular esters, acylation appears to be the rate limiting catalytic step.

Catalysis↗
PubMedDate not supplied

The detection of Rh antigens (D,C,c,E,e) on bloodstains by a micro-elution technique using low ionic strength solution (LISS) and papain-treated red cells.

Ninety experimental bloodstains, were examined, with the intention of detecting the principal Rh antigens, by using a micro-elution method improved by the use of low ionic strength solution (LISS) and papain-treated red cells. This method makes it possible to employ most commercially produced sera in routine forensic haematology laboratory work. The antigens could regularly be detected in stains of the following ages: D, C and c in stains of at least 6 months, E in stains of at least 4 months, and e in stains of at least 2 months.

Antigens↗
PubMed2004

Low molecular weight chitosans: preparation with the aid of papain and characterization.

Low molecular weight chitosans (LMWC) of different molecular weight (4.1-5.6 kDa) were obtained by the depolymerization of chitosan using papain (from Carica papaya latex, EC. 3.4.22.2) at optimum conditions of pH 3.5 and 37 degrees C for 1-5 h. Scanning electron microscopy (SEM) showed approximately 15-fold decrease in the particle size after depolymerization. Decrease in the molecular weight was associated with decrease in the degree of acetylation (DA) as evidenced by circular dichroism (CD), FT-IR and solid-state CP-MAS 13C-NMR data. X-ray diffraction pattern revealed slight decrease in the crystallinity index (CrI) whereas the 13C-NMR data showed molecular inhomogeneity. LMWC showed lytic effect towards Bacillus cereus and Escherichia coli more efficiently than native chitosan. The growth inhibitory effect was maximal towards B. cereus, with minimum inhibitory concentration (MIC) of 0.01% (w/v).

Acetylation↗
PubMed2006

The catalytic mode of cysteine proteinases of papain (C1) family.

The Proton Inventory (PI) method has been applied in the hydrolysis of synthetic substrates by papain, chymopapain and stem bromelain, comparing also their corresponding pH-(k(cat)/K(m)) profiles, and it was found: (a) k(cat)/K(m)=k(1), and thus K(S)=k(2)/k(1) is a dynamic equilibrium constant, (b) bowed-downward PI for k(cat)/K(m) exhibiting large inverse SIE, and (c) linear PI exhibiting large normal SIE for K(S), k(2) and k(3). A novel finding of this work is that the association of substrates onto all three studied cysteine proteinases proceeds via a stepwise pathway, in contrast to purely concerted pathways found previously for both acylation and deacylation. A hydrogen bond, which seems more likely to be developed across a pK(a)-value close to 4.00, connecting [see text] (papain/chymopapain or bromelain numbering), constitutes another novelty of this work.

Bromelains↗