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PubMed1985

The incidence and clinical implications of hypersensitivity to papain in an allergic population, confirmed by blinded oral challenge.

Five hundred allergy clinic patients were prick skin tested with papain, 1 mg/mL, in addition to usual local aeroallergens. Five of 475 subjects with seasonal allergic disease had positive skin tests to both papain and local pollens. None of the 25 individuals with negative skin test to pollens had skin reactivity to papain. The five subjects with positive skin tests to papain underwent double-blind placebo-papain challenges. All papain challenges were positive. Placebo challenges were negative. Papain-induced symptoms included palatal itching, watering itchy eyes, sneezing, rhinorrhea, abdominal cramps, diarrhea, and diaphoresis. Circulating papain-specific IgE was detected in all the papain-sensitive individuals, but not in control subjects. Confirmed papain sensitivity occurred in 1.05% of allergic subjects. In the papain-sensitive patients, cross-reacting antibodies with chymopapain were found. The small number of non-allergic subjects did not show any papain or chymopapain sensitivity in vitro.

Administration, Oral↗
PubMed1978

Conversion of the active-site cysteine residue of papain into a dehydro-serine, a serine and a glycine residue.

Photolysis of papain which had been inhibited with 2-bromo-2',4'-dimethoxyacetophenone regenerated papain, but also formed [deltaSer25]-papain (i.e. papain in which the active-site cysteine residue 25 was replaced by dehydroserine) via the intermediate dehydrocysteine analogue, [deltaCys25]-papain. Reduction with sodium borohydride gave [Ser25]papain. Both [Ser25]papain and [deltaSer25]-papain had binding properties similar to those of papain, but were devoid of enzymic activity. Their fluorescence properties were also investigated. Incubation of [deltaSer25]papain at pH 9.0 gave [Gly25]papain.

Acetophenones↗
PubMed1994

Active site structure and stability of the thiol protease papain studied by electron paramagnetic resonance employing a methanethiosulfonate spin label.

The electron paramagnetic resonance (EPR) spin labeling technique has been employed to study the properties and conformation of the thiol protease papain in solution, using (1-oxyl-2,2,5,5-tetramethyl-delta 3-pyrroline-3-methyl) methanethiosulfonate (MTS) as the spin label. The measurements of papain's amidase activity corroborate the EPR results. The major findings are: (i) the motion of the MTS spin label is very sensitive to the active site conformation of papain, which may reflect the location of the pyrroline ring of the spin label near the narrow portion of the active site cleft of papain, and thus there may be intimate interactions between the spin label and its environment; (ii) the active site cleft of papain may have a more open structure at intermediate pH (pH 4.2 to 8.0) than at higher (pH > 8.0) or lower (pH < 4.2) pH, which is consistent with the bell-shape pH curve of the enzyme's amidase activity with the optimum pH at pH 7.00; and (iii) the motion of spin label at the active site of free papain in solution becomes slower upon addition of a denaturant (urea or guanidine hydrochloride), suggesting that the denatured enzyme may have a more closed active site cleft. Urea is more effective than guanidine hydrochloride in denaturing papain at low concentration. However, both urea and guanidine hydrochloride can completely inactivate papain at high concentrations. When an appropriate spin label is selected to label the active site of papain (such as MTS spin label), the EPR spin labeling technique may offer additional insight into the conformation of papain over that obtained by optical methods. These results are discussed in terms of possible studies of biofunctional membranes, opaque assemblies in which a biological molecule is attached to a polymeric membrane.

Binding Sites↗
PubMed2000

Single disulfide bond reduced papain exists in a compact intermediate state.

Partially reduced proteins and other chemically modified derivatives are very useful model systems to understand the protein folding in vivo. Upon reduction, proteins attain different conformations with varying degrees of compactness. The reduction of papain in the presence of 8 M urea leads to the partial reduction of one disulfide bond. This derivative (single disulfide reduced carboxymethylated 1RCM papain (3RCM papain)) was characterized by spectroscopic methods and the effect of this reduction on the unfolding of the protein was investigated. Under this partial reduction, papain exhibits more than half of the tertiary and most of the secondary structures relative to the non-reduced molecule (free cysteine reduced and carboxymethylated papain (1RCM papain)). Hydrophobic regions are exposed to the solvent as observed through 8-anilino-1-naphthalene sulfonic acid binding which was absent in the fully intact and unfolded protein, at neutral pH. Hydrodynamic studies indicated that 3RCM papain, under neutral conditions, possess expanded conformation as compared to the native protein. Tryptophan fluorescence quenching studies suggested the exposure of aromatic residues to solvent. Guanidine hydrochloride induced unfolding of this derivative, at neutral pH, showed a non-cooperative transition contrary to the cooperativity seen with intact protein. Thermal unfolding indicates that 3RCM papain is less stable compared to the intact protein. These findings suggest that partial reduction of papain has a significant effect on the unfolding behavior of papain.

Anilino Naphthalenesulfonates↗
PubMed1989

Interaction of chicken cystatin with inactivated papains.

Papain which was inactivated by covalent attachment of small substituents to the active-site cysteine, up to the size of a carbamoylmethyl group, bound with high affinity to chicken cystatin (Kd less than approximately 15 pM), although less tightly than did active papain (Kd approximately 60 fM). However, as the size of the substituent was increased further, the affinity decreased appreciably, generally in proportion to the size of the inactivating group. For instance the dissociation constants for papain inactivated with N-ethylmaleimide and [N-(L-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]-amido-(4-guanido )butane were 0.17 and approximately 10 microM respectively. The spectroscopic changes accompanying the reaction of all but the most weakly binding (Kd greater than or equal to 2 microM) inactivated papains with cystatin were similar to those induced by the active enzyme. Interactions involving the reactive cysteine residue of papain are thus not crucial for high-affinity binding of the enzyme to cystatin, in accordance with a recently proposed model for the enzyme-inhibitor complex, based on computer docking experiments. In this model there is sufficient space around the reactive cysteine in the complex for a small inactivating group, explaining the tight binding of papains with such substituents. However, larger inactivating groups cannot be accommodated in this space and therefore must displace the inhibitor out of the tight fit with the enzyme, in agreement with the observed decrease in binding affinity with increasing size of bulkier substituents. The kinetics of binding of cystatin to inactivated papains were compatible with simple, reversible, bimolecular reactions, having association rate constants of (7-9) x 10(6) M-1 s-1 at pH 7.4, 25 degrees C, similar to what was shown previously for the binding of cystatin to active papain. The rate of association of the inhibitor with either active or inactivated papain thus appears to be primarily diffusion-controlled. The decreasing affinity of cystatin for papains inactivated with groups of increasing size was shown to be due to progressively higher dissociation rate constants, consistent with the greater impairment of fit between the binding regions of the two molecules.

Animals↗
PubMed1998

Inactivation of papain by antithrombin due to autolytic digestion: a model of serpin inactivation of cysteine proteinases.

Cross-class inhibition of cysteine proteinases by serpins differs from serpin inhibition of serine proteinases primarily in that no stable serpin-cysteine proteinase complex can be demonstrated. This difference in reaction mechanism was elucidated by studies of the inactivation of the cysteine proteinases, papain and cathepsin L, by the serpin antithrombin. The two proteinases were inactivated with second-order rate constants of (1.6+/-0.1)x10(3) and (8.6+/-0. 4)x10(2) M-1.s-1 respectively. An antithrombin to papain inactivation stoichiometry of approximately 3 indicated extensive cleavage of the inhibitor concurrent with enzyme inactivation, a behaviour verified by SDS/PAGE. N-terminal sequence analyses showed cleavage predominantly at the P2-P1 bond, but also at the P2'-P3' bond of antithrombin. The papain band in SDS/PAGE progressively disappeared on reaction of the enzyme with increasing amounts of antithrombin, but no band representing a stable antithrombin-papain complex appeared. SDS/PAGE with 125I-labelled papain showed that the disappearance of papain was caused by cleavage of the enzyme into small fragments. These results suggest a mechanism in which papain attacks a peptide bond in the reactive-bond loop of antithrombin adjacent to that involved in serine proteinase inhibition. The reaction proceeds, similarly to that between serpins and serine proteinases, to form an inactive acyl-intermediate complex, although with the substrate pathway dominating in the papain reaction. In this complex, papain is highly susceptible to proteolysis and is degraded by still active papain, which greatly decreases the lifetime of the complex and results in liberation of fragmented, inactive enzyme. This model may have relevance also for the inactivation of physiologically or pathologically important cysteine proteinases by serpins.

Antithrombins↗
PubMed1993

Expression of functional papain precursor in Saccharomyces cerevisiae: rapid screening of mutants.

A microbial expression system for the study of the cysteine protease papain has been developed as a more useful alternative to the insect cell/baculovirus expression system we have previously used. A synthetic papain precursor (propapain) gene was expressed in the yeast Saccharomyces cerevisiae under the control of the alpha-factor promoter. Efficient expression required fusion of the propapain sequence with the yeast alpha-factor prepro region and a yeast host cell defective in the synthesis of vacuolar proteases. Surprisingly, the glycosylated form of the inactive papain precursor is not secreted, but accumulates within the yeast cell. Complete conversion of the intracellular zymogen into active mature papain could be achieved in vitro. Purified recombinant papain produced by the yeast system has kinetic characteristics similar to those of the natural enzyme. An advantage of the yeast expression system over the baculovirus/insect cell system is that we can perform mutagenesis and screening of papain mutants very efficiently. We have set up a 'one-tube' screening procedure for the simultaneous characterization of numerous mutants of the papain precursor. Yeast cells are grown and lysed in microtiter plate wells and the released papain precursor is then activated to mature papain. This assay allows easy discrimination between proteins with close to wild type properties and proteins that are not functional. We have applied this assay to investigate the spectrum of amino acids which are tolerated at Asn175 of papain using two independently derived libraries of mutants at this position. Many amino acid substitutions at this position are not accepted; only the reintroduction of Asn restored normal function.

Amino Acid Sequence↗
PubMed1975

Formation and repair of papain sulfenic acid.

The inactivation of highly purified papain (2 times 10- minus 5M-minus 1 min-minus 1) for papain: peroxide molar ratios of 1:1 or 2:1. Loss of activity is accompanied by a parallel loss of sulfhydryl; however, the sulfhydryl losses, as determined with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNG) or p-hydroxymercuribenzoate (pHMB), are anomalously either too large or too small, respectively. These discrepancies resulted from the reaction of inactive papain with either the thiol anion product of the DTNB reaction, or with the pHMB reagent itself. The addition of 1.2M urea to the DTNB reaction mixture significantly decreased this error. Inactive papain reacted with high concentrations of cysteine or cyanide to yield completely repaired active papain, and with benylamine to yield non-repairable, inactive papain. Sodium arsenite, which is capable ofreducing sulfenic acids but not disulfide bonds, readily repaired peroxide-inactivated papain. A completely inactive but repairable papain fraction was isolated by virtue of its lessened ability to bind to a tetrapeptide inhibitor immobilized on Sepharose. The cumulative results indicate that the peroxide inactivation of papain is due almost exclusively to the formation of papain sulfenic acid (Cys25-SOH).

Arsenic↗
PubMed1993

An amplified assay for thiols based on reactivation of papain.

A sensitive spectrophotometric assay has been developed for thiol (sulfhydryl) groups using an inactive disulfide derivative of papain (papain-S-SCH3). The thiol-disulfide interchange reaction of a thiol with papain-S-SCH3 results in the stoichiometric formation of active papain (papain-SH). The reactivated papain catalyzes the hydrolysis of a chromogenic substrate, resulting in an amplified spectrophotometric signal proportional to the initial amount of thiol. A variety of thiols, e.g., cysteine, glutathione, penicillamine, cysteine methyl ester, and cysteamine, yield similar linear plots for the activity of papain vs the initial amount of thiol. An unknown concentration of a thiol is measured using a standard plot for the activity of papain vs the amount of thiol, obtained for the same thiol or for a similar thiol. Thiol groups on proteins and thiol groups of high values of pKa (2-mercaptoethanol, 3-mercaptopropanoic acid) can also be assayed using papain-S-SCH3 in the presence of excess cystamine. The assay is about 100-fold more sensitive than that using Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid)]. A 0.4 microM solution of cysteine produces an absorbance change of 0.55 at 410 nm after 30 min in the assay, compared to a predicted change in absorbance of 0.0054 using Ellman's assay.

Aniline Compounds↗
PubMed1994

Interaction of ebselen with glutathione S-transferase and papain in vitro.

The interaction of ebselen(2-phenyl-1,2-benzisoselenazol-3(2H)-one) with rat liver cytosolic glutathione S-transferases (GSTs) and the plant cysteine protease, papain, was studied as cysteine residues are important for the activity of these enzymes. The capacity of GST 1-2 and 3-4 for ebselen binding is similar (1.5 mol ebselen/mol GST isozyme), while GST 2-2 and GST 7-7 bind 0.3 and more than 2.0 mol ebselen/mol GST isozyme, respectively. Ebselen does not bind to N-ethylmaleimide-treated GST, and its binding to GST is prevented by 5 mM thiols. Ebselen irreversibly inactivates the different GST isozymes with a second order rate constant ranging from 20 to 2250 M-1 sec-1 for the different subunits. GST inhibition by ebselen is partially restored by 5 mM thiols. Ebselen binds to untreated papain and to cysteine-treated papain at a ratio of about 0.1 and 0.75 mol ebselen/mol papain, respectively. Ebselen does not bind to N-ethylmaleimide-treated papain, and its binding to papain is interfered with by added thiols. Papain is inactivated by ebselen with a second order rate constant of 1800 M-1 sec-1 in the absence of thiols. However, in the presence of GSH, 2-mercaptoethanol or sodium borohydride, ebselen exerts an activating effect on papain. The binding of ebselen by a seleno-sulfide bond to cysteine residues of GSTs and papain leads to their inactivation.

Animals↗
PubMed1981

Modification by papain of the structure and function of band 3, the erythrocyte anion transport protein.

Extracellular papain is known to inhibit the anion transport function of the band 3 protein of the human red blood cell membrane. Previous work [Jennings, M. L., & Passow, H. (1979) Biochim. Biophys. Acta 554, 498-519] had suggested that this inhibition may result from the removal by papain of 5 000-10 000 daltons from the 35 000-dalton chymotryptic peptide of band 3. The present work shows, however, that papain also removes a small peptide from the C terminus of the 60 000-dalton chymotryptic peptide. The C-terminal amino acid sequence of this peptide is -Lys-Thr-Tyr. Whether or not this newly discovered action of papain is responsible for inhibiting anion transport is unknown. The effects of extracellular papain on the band 3 function have been characterized in detail. Papain inhibits Cl-Cl exchange in a high Cl medium by almost 90%. This inhibition appears to result from inhibition of the efflux step in the catalytic cycle for the transport, because papain does not inhibit the anion transport when it is assayed under influx-limited conditions. Moreover, since papain has no detectable effect on the dissociation constant for extracellular substrate (SO4) binding, the material removed by papain cannot be involved closely in the outward-facing substrate site. In contrast, removal of this material strongly (12-fold) reduces the affinity of the inhibitor 4,4'-dinitro-2,2'-stilbenedisulfonate for outward-facing sites. Therefore, stilbenedisulfonate binding involves portions of the band 3 molecule which are not intimately related to substrate binding.

Adult↗
PubMed1966

The kinetics of papain- and ficin-catalysed hydrolyses in the presence of alcohols.

1. The maximum rate of production of p-nitrophenol (V(max.)) for both papain- and ficin-catalysed hydrolyses of p-nitrophenyl hippurate is independent of methanol concentration up to 2m for papain and 1.5m for ficin. 2. The observed catalytic constant (k(0)) for the production of hippuric acid for both papain- and ficin-catalysed hydrolyses of methyl hippurate decreases with increasing methanol concentration, 1/k(0) being linearly dependent on the methanol concentration. The k(MeOH)/k(H2O) ratio is determined. 3. These results provide strong evidence against general base catalysis for the rate-determining step in the deacylation of hippuryl-papain and hippuryl-ficin and probably for other specific acyl-papains and acyl-ficins. 4. The rate-determining step for the deacylation of the non-specific trans-cinnamoyl-papain appears to be different from that for the specific hippuryl-papain, and is probably subject to general base catalysis. It is possible, however, to accommodate all these observations in a single four-step reaction pathway. 5. Propan-2-ol did not influence the rate of production of hippuric acid for the papain-catalysed hydrolysis of methyl hippurate. A similar result has previously been reported for the ficin-catalysed hydrolysis of methyl hippurate. Ethanol and of course methanol (see 2) decrease the rate of production of hippuric acid for both papain- and ficin-catalysed hydrolyses of methyl hippurate. It is suggested that the secondary alcohol is incapable for structural reasons of approaching the bond to be hydrolysed.

1-Propanol↗
PubMed1956

Reversible collapse of rabbit ears after intravenous papain, and prevention of recovery by cortisone.

A substance has been demonstrated in solutions of crude papain, which, when injected intravenously into 1 kilo rabbits, in amounts less than 5 mg., results in complete collapse of both ears. The phenomenon becomes visible 4 hours after injection, and is complete within 24 hours. 3 or 4 days after papain, the ears gradually reassume their normal form. Ear collapse is associated with depletion of the ear cartilage matrix, and the disappearance of basophilia from the matrix. Similar changes occur in all other cartilage tissues, including bones, joints, larynx, trachea, and bronchi. At the time when the ears are restored to normal shape, the basophilic matrix reappears in cartilage. Repeated injections of papain, over a period of 2 or 3 weeks, bring about immunity to the phenomenon of ear collapse. When the arterial circulation to one ear is occluded for 15 minutes at the time of injection of papain, this ear is protected against collapse. The effect of crude papain could not be reproduced by crystalline papain protease or crystalline papain lysozyme, which together comprise a considerable portion of the dry weight of papain. The nature of the responsible factor has not been determined, and the possibility that chymopapain may be implicated is currently under study. Cortisone prevents the return of papain-collapsed ears to their normal shape and rigidity. Possibly this reflects a capacity of cortisone to impede the synthesis or deposition of sulfated mucopolysaccharides in tissues.

Animals↗
PubMedDate not supplied

Papain: a novel urine adulterant.

The estimated number of employees in the United Stated screened annually for illicit drugs is approximately 20 million, with marijuana being the most frequently abused drug. Urine adulterants provide an opportunity for illicit drug users to obtain a false-negative result on commonly used primary drug screening methods such as the enzyme multiplied immunoassay technique and the fluorescence polarized immunoassay technique (FPIA). Typical chemical adulterants such as nitrites are easily detected or render the urine specimen invalid as defined in the proposed SAMHSA guidelines for specimen validity testing based on creatinine, specific gravity, and pH. Papain is a cysteine protease with intrinsic ester hydrolysis capability. The primary metabolite of the psychoactive chemical in marijuana, 11-norcarboxy-Delta9-tetrahydrocannibinol (THC-COOH), was assayed by FPIA in concentrations ranging from 25 to 500 ng/mL, at pH values ranging from 4.5 to 8, over the course of 3 days with papain concentrations ranging from 0 to 10 mg/mL. FPIA analysis of other frequently abused drugs: amphetamines, barbiturates, benzodiazepines, cocaine, opiates, and phencyclidine, along with gas chromatography-mass spectrometry (GC-MS) of THC-COOH and high-pressure liquid chromatography-ultraviolet detection (HPLC-UV) of nordiazepam was performed in order to determine if the mechanism of urine adulteration by papain was analyte specific. Control and adulterated urine specimens (n = 30) were assayed for creatinine, specific gravity, and pH to determine if papain rendered the specimens invalid based on the proposed SAMHSA guidelines. There was a direct pH, temperature, and time-dependent correlate between the increase in papain concentration and the decrease in THC-COOH concentration from the untreated control groups (p < 0.01). The average 72-h THC-COOH concentration decrease at pH 6.2 with a papain concentration of 10 mg/mL was 50%. Papain did not significantly decrease the concentration of the other drugs analyzed with the exception of nordiazepam. GC-MS of THC-COOH and HPLC-UV of nordiazepam revealed a 66% and 24% decrease in concentration of the respective analyte with 10 mg/mL papain after 24 h at room temperature (approximately 23 degrees C). No adulterated specimens were rendered invalid based on the SAMHSA guidelines. Immediate FPIA analysis is suggested to minimize the interfering effects of papain with regards to primary drug screening.

Chromatography, High Pressure Liquid↗
PubMed1976

Inhibition of papain by isothiocyanates.

During the tapping of papaya latex for papain (EC 3.4.22.2), benzyl isothiocyanate is enzymatically produced from benzylglucosinolate, a major component of the latex fluid. Benzyl isothiocyanate inhibits papain hydrolysis of alpha-N-benzoyl-L-arginine ethyl ester (Bz-Arg-OEt). Since tha availability of the papain sulfhydryl group to 5,5'-dithiobis-2-nitrobenzoid acid (Nbs2) is inversely related to the extensiveness of the isothiocyanate inhibition, and treatment by benzyl isothiocyanate reduces the affinity of activated papain to a mercurial-Sepharose column, it is proposed that the papain sulfhydryl reacts with the electrophilic functional group of this inhibitor. Fifteen isothiocyanates were selected and both the chemical reactivity antors are involved in the isothiocyanate-papain inhibition: (1) chemical reactivity of isothiocyanates, (2) presence or absence of an aromatic substitution, and (3) the spatial relationship of the aromatic moiety to the -N = C = S group of isothiocyanates. These data further suggest the presence of an 'aromatic site' near the Cys-25 sulfhydryl group of activated papain. Based on the existing model of papain molecule, the imidazole group of His-159 coincides well with our proposed aromatic site. The prospects of using isothiocyanates as chemical probes for the study of chemical environment of active sites in other enzymes are briefly discussed.

Binding Sites↗
PubMed1994

Spacer effects on enzymatic activity of papain immobilized onto porous chitosan beads.

Papain was covalently immobilized onto the surface of porous chitosan beads without or with spacers of different lengths. The relative activity of the immobilized papain was found to be high toward a small ester substrate, N-benzyl-L-arginine ethyl ester (BAEE), but rather low toward casein, a high molecular weight substrate. Papain immobilized with spacer gave an almost constant activity, in marked contrast with the immobilized papain without spacer, whose activity monotonously decreased with decreasing surface concentration. The relative activity of the immobilized papain for hydrolysis of a high molecular weight substrate greatly depended on the length of the spacer. The pH, thermal and storage stabilities of the immobilized papain were higher than those of the free one, and ths papain immobilized directly to the chitosan beads' surface without any spacer gave a higher stability than those immobilized with spacer. The spacer's effect on the activity could be explained in terms of mobility of the immobilized papain molecule.

Arginine↗
PubMed2006

Glycosylation in the Fc domain of IgG increases resistance to proteolytic cleavage by papain.

IgG antibodies (Abs) and fragments of IgG Abs are becoming major biotherapeutics to treat an assortment of human diseases. Commonly prepared fragments of IgGs include Fc, Fab, and F(ab')2 fragments, all of which can be made using the sulfhydryl protease papain, although prolonged digestion times and/or excessive amounts of papain typically result in further cleavage of the Fc domain into smaller fragments. During our attempts to use papain to isolate Fc fragments from different IgG monoclonal Abs, it was observed that prior removal of Fc glycans resulted in a faster rate of papain-mediated degradation of the Fc domain. Subsequent time-course experiments comparing glycosylated and deglycosylated versions of IgG antibodies showed that the majority of molecules in a deglycosylated IgG sample were converted into Fab, Fc, and smaller Fc fragments in less than one hour, whereas the original glycosylated IgG required more than two hours to convert into a comparable amount of Fab and Fc fragments. Furthermore, whereas papain digestion converted almost all of a deglycosylated Fc fragment into smaller fragments of approximately 10 and approximately 12 kDa within 4 h, more than 40% of a glycosylated Fc fragment remained intact even after 24 h of digestion. These results indicate that the presence of CH(2) domain glycans in either IgGs or purified Fc fragments increases resistance to papain digestion. Increased sensitivity of non-glycosylated Fc domains to papain is consistent with the Fc domains lacking a defined structure, as exemplified by their inability to bind Fcgamma receptors, since misfolded proteins are often degraded by proteases because of increased accessibility of their proteolytic cleavage sites. Based on these observations it is possible to use papain sensitivity as a means of assessing proper Fc structure of IgG molecules.

Animals↗
PubMed1978

Respiratory hazards from papain.

Late-onset asthma occurred in a non-atopic worker in a factory where papain powder was packed. The patient had had 3 attacks of asthma since first being exposed to atmospheric papain dust. He gave a positive immediate reaction to skin-prick tests with solutions of papain which were appreciably weaker than solutions which caused no reaction in unexposed individuals. These results, together with his history and the fact that symptoms stopped when he was not exposed to papain, suggest that he had extrinsic allergic asthma caused by sensitisation to papain. Shortly after re-exposure to papain a worker in another factory died during an attack of asthma. Measures to prevent the inhalation of papain dust must be taken in factories where papain is handled, not only to avoid the proteolytic effects of the material but also to prevent workers from becoming sensitised.

Air Pollutants↗