A purification and some properties of two proteases from papaya latex

The proteolytic system of pineapple stems revisited: Purification and characterization of multiple catalytically active forms

Crude pineapple proteases extract (aka stem bromelain; EC 3.4.22.4) is an important proteolytic mixture that contains enzymes belonging to the cysteine proteases of the papain family. Numerous studies have been reported aiming at the fractionation and characterization of the many molecular species present in the extract, but more efforts are still required to obtain sufficient quantities of the various purified protease forms for detailed physicochemical, enzymatic and structural characterization. In this work, we describe an efficient strategy towards the purification of at least eight enzymatic forms. Thus, following rapid fractionation on a SP-Sepharose FF column, two sub-populations with proteolytic activity were obtained: the unbound (termed acidic) and bound (termed basic) bromelain fractions. Following reversible modification with monomethoxypolyethylene glycol (mPEG), both fractions were further separated on Q-Sepharose FF and SP-Sepharose FF, respectively. This procedure yielded highly purified molecular species, all titrating ca. 1 mol of thiol group per mole of enzyme, with distinct biochemical properties. N-terminal sequencing allowed identifying at least eight forms with proteolytic activity. The basic fraction contained previously identified species, i.e. basic bromelain forms 1 and 2, ananain forms 1 and 2, and comosain (MEROPS identifier: C01.027). Furthermore, a new proteolytic species, showing similarities with basic bomelain forms 1 and 2, was discovered and termed bromelain form 3. The two remaining species were found in the acidic bromelain fraction and were arbitrarily named acidic bromelain forms 1 and 2. Both, acidic bromelain forms 1, 2 and basic bromelain forms 1, 2 and 3 are glycosylated, while ananain forms 1 and 2, and comosain are not. The eight protease forms display different amidase activities against the various substrates tested, namely small synthetic chromogenic compounds (DL-BAPNA and Boc-Ala-Ala-Gly-pNA), fluorogenic compounds (like Boc-Gln-Ala-Arg-AMC, Z-Arg-Arg-AMC and Z-Phe-Arg-AMC), and proteins (azocasein and azoalbumin), suggesting a specific organization of their catalytic residues. All forms are completely inhibited by specific cysteine and cysteine/serine protease inhibitors, but not by specific serine and aspartic protease inhibitors, with the sole exception of pepstatin A that significantly affects acidic bromelain forms 1 and 2. For all eight protease forms, inhibition is also observed with 1,10-phenanthrolin, a metalloprotease inhibitor. Metal ions (i.e. Mn²⁺, Mg²⁺ and Ca²⁺) showed various effects depending on the protease under consideration, but all of them are totally inhibited in the presence of Zn²⁺. Mass spectrometry analyses revealed that all forms have a molecular mass of ca. 24 kDa, which is characteristic of enzymes belonging to the papain-like proteases family. Far-UV CD spectra analysis further supported this analysis. Interestingly, secondary structure calculation proves to be highly reproducible for all cysteine proteases of the papain family tested so far (this work; see also Azarkan et al., 2011; Baeyens-Volant et al., 2015) and thus can be used as a test for rapid identification of the classical papain fold.

Selective and reversible thiol-pegylation, an effective approach for purification and characterization of five fully active ficin (iso)forms from Ficus carica latex

The latex of Ficus carica constitutes an important source of many proteolytic components known under the general term of ficin (EC 3.4.22.3) which belongs to the cysteine proteases of the papain family. So far, no data on the purification and characterization of individual forms of these proteases are available. An effective strategy was used to fractionate and purify to homogeneity five ficin forms, designated A, B, C, D1 and D2 according to their sequence of elution from a cation-exchange chromatographic support. Following rapid fractionation on a SP-Sepharose Fast Flow column, the different ficin forms were chemically modified by a specific and reversible monomethoxypolyethylene glycol (mPEG) reagent. In comparison with their un-derivatized counterparts, the mPEG-protein derivatives behaved differently on the ion-exchanger, allowing us for the first time to obtain five highly purified ficin molecular species titrating 1mol of thiol group per mole of enzyme. The purified ficins were characterized by de novo peptide sequencing and peptide mass fingerprinting analyzes, using mass spectrometry. Circular dichroism measurements indicated that all five ficins were highly structured, both in term of secondary and tertiary structure. Furthermore, analysis of far-UV CD spectra allowed calculation of their secondary structural content. Both these data and the molecular masses determined by MS reinforce the view that the enzymes belong to the family of papain-like proteases. The five ficin forms also displayed different specific amidase activities against small synthetic substrates like dl-BAPNA and Boc-Ala-Ala-Gly-pNA, suggesting some differences in their active site organization. Enzymatic activity of the five ficin forms was completely inhibited by specific cysteine and cysteine/serine proteases inhibitors but was unaffected by specific serine, aspartic and metallo proteases inhibitors.

Potential of laticifer fluids for inhibiting Aedes aegypti larval development: evidence for the involvement of proteolytic activity

It has been shown previously that the laticifer fluid of Calotropis procera (Ait.) R.Br. is highly toxic to the egg hatching and larval development of Aedes aegypti L. In the present study, the larvicidal potential of other laticifer fluids obtained from Cryptostegia grandiflora R.Br., Plumeria rubra L. and Euphorbia tirucalli L. was evaluated. We attempted to correlate larvicidal activity with the presence of endogenous proteolytic activity in the protein fraction of the fluids. After collection, the fluids were processed by centrifugation and dialysis to obtain the soluble laticifer protein (LP) fractions and eliminate water insoluble and low molecular mass molecules. LP did not visibly affect egg hatching at the doses assayed. LP from Cr. grandiflora exhibited the highest larval toxicity, while P. rubra was almost inactive. E. tirucalli was slightly active, but its activity could not be correlated to proteins since no protein was detected in the fluid. The larvicidal effects of LP from C. procera and Cr. grandiflora showed a significant relationship with the proteolytic activity of cysteine proteinases, which are present in both materials. A purified cysteine proteinase (papain) from the latex of Carica papaya (obtained from Sigma) was similarly effective, whereas trypsin and chymotrypsin (both serine proteinases) were ineffective. The results provide evidence for the involvement of cysteine proteinase activity in the larvicidal action of some laticifer fluids. C. procera is an invasive species found in areas infested with Ae. aegypti and thus could prove useful for combating mosquito proliferation. This is the first report to present evidence for the use of proteolytic enzymes as chemical agents to destroy Ae. aegypti larvae.

Preparation and Characterization of a Truncated Caricain Lacking 41 Residues from the N-terminal

We purified an 18.8 kD protease from caricain solution. This protease was derived from caricain. It does not have the first 41 residues of the N-terminal sequence of caricain, and its N-terminal residue is Thr. Also, one of the disulfide bonds of caricain (cys22-cys63) was opened during the formation of the protease. We named this 18.8 kD protease caricain II. Caricain II has a wide pH range, and it is more sensitive to temperature changes than caricain. The proteolytic activity of caricain II is twice as much as that of caricain using casein as a substrate. However, caricain II has a low hydrolytic activity with N-benzoyl-L-arginine ethyl ester (BAEE) that is one of the special substrates of caricain. Our results indicate that caricain II is remarkably different from caricain and it can provide an improvement over caricain on the proteolytic activity.

Procerain, a stable cysteine protease from the latex of Calotropis procera

A protease was purified to homogeneity from the latex of medicinal plant Calotropis procera (Family-Asclepiadaceae). The molecular mass and isoelectric point of the enzyme are 28.8 kDa and 9.32, respectively. Hydrolysis of azoalbumin by the enzyme was optimal in the range of pH 7.0-9.0 and temperature 55-60 degree C. The enzyme hydrolyses denatured natural substrates like casein, azoalbumin, and azocasein with high specific activity. Proteolytic and amidolytic activities of the enzyme were activated by thiol protease activators and inhibited by thiol protease inhibitors, indicating the enzyme to be a cysteine protease. The enzyme named as procerain, cleaves N-succinyl-Ala-Ala-Ala-p-nitroanilide but not -Ala-Ala-p-nitroanilide, -Ala p-nitroanilide and N-d-Benzoyl--Arg-p-nitroanilide and appears to be peptide length dependent. The extinction coefficient (epsilon 1% 280 nm) of the enzyme was 24.9 and it had no detectable carbohydrate moiety. Procerain contains eight tryptophan, 20 tyrosine and seven cysteine residues forming three disulfide bridges, and the remaining one being free. Procerain retains full activity over a broad range of pH 3.0-12.0 and temperatures up to 70 degree C, besides being stable at very high concentrations of chemical denaturants and organic solvents. Polyclonal antibodies against procerain do not cross-react with other related proteases. Procerain unlike most of the plant cysteine proteases has blocked N-terminal residue.

Purification and biochemical characterization of a highly active cysteine protease ervatamin A from the latex of Ervatamia coronaria

Ervatamia coronaria, a flowering plant (family Apocynaceae) indigenous to India, has medicinally important applications. A search for biochemical constituents of the latex of the plant yielded at least three thiol proteases with distinctly different properties. One of them, a highly active protease (ervatamin A), was purified to homogeneity by ion exchange and gel filtration chromatography. The enzyme exhibited high proteolytic activity toward natural substrates and amidolytic activity toward synthetic substrates. The pH and temperature optima for proteolytic activity were 8-8.5 and 50-55 degrees C, respectively. Proteolytic activity of the enzyme was strongly inhibited by thiol-specific inhibitors. The estimated molecular mass of the enzyme was 27.6 kDa. The extinction coefficient (epsilon(1%) 280) of the enzyme was estimated as 21.9, and the protein molecule consists of 8 tryptophan, 11 tyrosine and 7 cysteine residues. Isoelectric point of the purified enzyme was 8.37. Polyclonal antibodies raised against the pure enzyme gave a single precipitin line in Ouchterlony's double immunodiffusion and a typical color in ELISA. The N-terminal sequence of the enzyme showed conserved amino acid residues to other plant cysteine proteases. Ervatamin A shows high activity in relation to the other thiol proteases isolated from the same source.

The structural origins of the unusual specificities observed in the isolation of chymopapain M and actinidin by covalent chromatography and the lack of inhibition of chymopapain M by cystatin

1. The selectivity observed when the potentially general technique for the isolation of fully active forms of cysteine proteinases, covalent chromatography by thiol-disulphide interchange, is applied to chymopapain M and to actinidin was investigated by a combination of experimentation and computer modelling. Neither of these enzymes is able to react with the original Sepharose-GSH-2-dipyridyl disulphide gel, but fully active forms of both enzymes are obtained by using Sepharose-2-hydroxypropyl-2'-dipyridyl disulphide gel, which is both electrically neutral and sterically less demanding than the GSH gel. Electrostatic potential calculations, minimization and molecular-dynamics simulations provide explanations for the unusual, but different, specificities exhibited by actinidin and chymopapain M in the interactions of their active centres with ligands. 2. The unique behaviour of chymopapain M in exerting an almost absolute specificity for substrates with glycine at the P1 position and in resisting inhibition by cystatin was examined by the computer-modelling techniques. A new, modelled, structure of the complete chicken egg-white cystatin molecule based on the crystal structure of a short form of cystatin was deduced as a necessary prerequisite. The results suggest that electrostatic repulsion prevents reaction of actinidin with the GSH gel, whereas a steric 'cap' resulting from a unique arginine-65-glutamic acid-23 interaction in chymopapain M prevents reaction of the gel with this enzyme and accounts for the lack of its inhibition by cystatin and its specificity in catalysis. 3. Use of chymopapain M as a structural variant of papain demonstrates the validity of the predictions of Lowe and Yuthavong [Biochem. J. (1971) 124, 107-115] relating to the structural requirements and binding characteristics of the S1 subsite of papain.

Structure of chymopapain M the late-eluted chymopapain deduced by comparative modelling techniques and active-centre characteristics determined by pH-dependent kinetics of catalysis and reactions with time-dependent inhibitors: the Cys-25/His-159 ion-pair is insufficient for catalytic competence in both chymopapain M and papain

Chymopapain M, the monothiol cysteine proteinase component of the chymopapain band eluted after chymopapains A and B in cation-exchange chromatography, was isolated from the dried latex of Carica papaya and characterized by kinetic and chromatographic analysis. This late-eluted chymopapain is probably a component of the cysteine proteinase fraction of papaya latex discovered by Schack [(1967) Compt. Rend. Trav. Lab. Carlsberg 36, 67-83], named papaya peptidase B by Lynn [(1979) Biochim. Biophys. Acta 569, 193-201] and partially characterized by Polgár [(1981) Biochim. Biophys. Acta 658, 262-269] and is the enzyme with unusual specificity characteristics (papaya proteinase IV) that Buttle, Kembhavi, Sharp, Shute, Rich and Barrett [Biochem. J. (1989) 261, 469-476] claimed to be a previously undetected cysteine proteinase eluted from a cation-exchange column near to the early-eluted chymopapains. A study of the time-dependent chromatographic consequences of thiol-dependent proteolysis of the components of papaya latex is reported. Chymopapain M was isolated by (i) affinity chromatography followed by separation from papain using cation-exchange f.p.l.c. on a Mono S HR5/5 column and (ii) cation-exchange chromatography followed by an unusual variant of covalent chromatography by thiol-disulphide interchange. The existence in chymopapain M of a nucleophilic interactive Cys/His catalytic-site system analogous to those in papain (EC 3.4.22.2) and other cysteine proteinases was deduced from the characteristics shape of the pH-second-order rate constant (k) profiles for its reactions with 2,2'-dipyridyl disulphide and ethyl 2-pyridyl disulphide. Analysis of the pH-k data for the reactions of chymopapain M with the 2-pyridyl disulphides and with 4,4'-dipyridyl disulphide permits the assignment of molecular pKa values of 3.4 and 8.7 to the formation and subsequent dehydronation of the Cys-S-/His-Im+H state of the catalytic site and reveals three other kinetically influential ionizations with pKa values 3.4, 4.3 and 5.6. The pH-dependences of kcat./Km for the hydrolysis of N-acetyl-L-Phe-Gly-4-nitroanilide at 25.0 degrees C and I0.1 M catalysed by chymopapain M and papain were determined. For both enzymes, little catalytic activity (5-7% of the maximal) develops consequent on formation of the catalytic site Cys-S-/His-Im+H ion-pair state (across pKa 3.4 for both enzymes). For papain, full expression of Kcat./Km for the uncharged substrate requires only the additional hydronic dissociation with pKa 4.2. By contrast, full expression of kcat./Km for chymopapain M requires additional hydronic dissociation with pKa values of 4.3 and 5.6.(ABSTRACT TRUNCATED AT 400 WORDS)

Fractionation and purification of the thiol proteinases from papaya latex

Three cysteine proteinases, i.e. chymopapain, papaya proteinase IV and proteinase III, were purified to homogeneity from papaya latex using a combination of ion-exchange chromatography and hydrophobic interaction chromatography. During the purification procedure, the thiol-groups of the active center were reversibly blocked as mixed disulfides with 2-thiopyridone. Homogeneity was proved electrophoretically by native polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate (SDS)-PAGE and rechromatography on a Mono S 5/5 column at pH 5.0.

Collagenolytic activity of crustacean midgut serine proteases: comparison with the bacterial and mammalian enzymes

1. We have investigated the collagenolytic activity of the following serine proteases: proteinase K, subtilisin Novo, Staphylococcal endoproteinase Glu-C, Streptomyces pronases, the trypsins and chymotrypsins from shrimp midgut and bovine pancreas. 2. By assays on both the insoluble 3H-collagen fibrils and the soluble type I collagen, it was demonstrated that the shrimp midgut serine proteases, and less efficiently, the pronases from Streptomyces griseus, could hydrolyze collagen while the other serine proteases tested could not. 3. Our data indicate that the trypsins and chymotrypsins of shrimp (Penaeus monodon) directly and indirectly digest native collagen, and that the indirect pathway probably involves activation of procollagenase in the native collagen by these serine proteases.

The amino acid sequence of chymopapain from Carica papaya

Chymopapain is a polypeptide of 218 amino acid residues. It has considerable structural similarity with papain and papaya proteinase omega, including conservation of the catalytic site and of the disulphide bonding. Chymopapain is like papaya proteinase omega in carrying four extra residues between papain positions 168 and 169, but differs from both papaya proteinases in the composition of its S2 subsite, as well as in having a second thiol group, Cys-117. Some evidence for the amino acid sequence of chymopapain has been deposited as Supplementary Publication SUP 50153 (12 pages) at the British Library Document Supply Centre, Boston Spa., Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms indicated in Biochem. J. (1990) 265, 5. The information comprises Supplement Tables 1-4, which contain, in order, amino acid compositions of peptides from tryptic, peptic, CNBr and mild acid cleavages, Supplement Fig. 1, showing re-fractionation of selected peaks from Fig. 2 of the main paper. Supplement Fig. 2, showing cation-exchange chromatography of the earliest-eluted peak of Fig. 3 of the main paper, Supplement Fig. 3, showing reverse-phase h.p.l.c. of the later-eluted peak from Fig. 3 of the main paper, and Supplement Fig. 4, showing the separation of peptides after mild acid hydrolysis of CNBr-cleavage fragment CB3.

Papaya proteinase IV amino acid sequence

The amino acid sequence of papaya proteinase IV (PPIV), a major proteinase from the latex of Carica papaya [(1989) Biochem. J. 261, 469-476] is described. The enzyme has a high degree of sequence identity with papaya proteinase III, chymopapain and papain (81, 70 and 67%, respectively), and is clearly a member of the papain superfamily of cysteine proteinases. Nevertheless, the sequence shows substitution of certain residues conserved in all other known members of the superfamily. It is suggested that some of these substitutions may account for the unusual specificity of PPIV.

Affinity purification of the novel cysteine proteinase papaya proteinase IV, and papain from papaya latex

A procedure is described for the purification of a previously undetected cysteine proteinase, which we have called papaya proteinase IV, from spray-dried latex of the papaya (Carica papaya) plant. The purification involves affinity chromatography on Gly-Phe-aminoacetonitrile linked to CH-Sepharose 4B, with elution by 2-hydroxyethyl disulphide at pH 4.5. The product thus obtained is a mixture of almost fully active papain and papay proteinase IV, which are then separated by cation-exchange chromatography. A preliminary characterization of papaya proteinase IV showed it to be very similar to chymopapain in both molecular size and charge. However, the new enzyme is immunologically distinct from the previously characterized cysteine proteinases of papaya latex. It also differs in its lack of activity against the synthetic substrates of the other papaya proteinases, in its narrow specificity against protein substrates and its lack of inhibition by chicken cystatin. Papaya proteinase IV is abundant, contributing almost 30% of the protein in spray-dried papaya latex, and contamination of chymopapain preparations with this enzyme may account for some of the previously reported heterogeneity of chymopapain.

Monoclonal antibodies to the two most basic papaya proteinases

The proteinases from Carica papaya include papain, isoenzymes of chymopapain and two proteinases A and B distinguished by their unusually high pI. The identity of one of the most basic proteinases has been questioned. The present report describes the preparation and characterisation of two monoclonal antibodies that react specifically with papaya proteinases A and B respectively and a third that identifies a common structural feature found in papain and proteinase A.

High-performance liquid chromatographic investigations on some enzymes of papaya latex

Papaya latex and commercial chymopapain have been examined by cation-exchange chromatography on a TSK SP 5PW column. Multiple components are observed and the resolution is superior to that obtained by low-pressure ion exchange. Most components display amidase activity. Fractions obtained from chymopapain by preliminary chromatography on SP-Sephadex have also been examined by the same procedure and by N-terminal and amino acid analysis. The results are consistent with the existence of chymopapain in multiple forms, the proportions of which alter. The chromatographic profile of chymopapain is influenced by the presence of cysteine in the sample.

Chymopapain. Chromatographic purification and immunological characterization

Chymopapain (EC 3.4.22.6) was purified from commercially available spray-dried latex of papaya (Carica papaya) fruit by (NH4)2SO4 fractionation and fast protein chromatography on the Mono S cation-exchange column. Multiple forms of chymopapain separated chromatographically were shown to be immunologically identical. A major form was isolated and found to be homogeneous by several criteria, and fully active, and its N-terminal amino acid was identified as tyrosine. Latex from fresh unripe papaya fruit contained predominantly one form of chymopapain, and it is concluded that chymopapain is a single enzyme distinct from the other cysteine proteinases of C. papaya latex.

Crystal and molecular structure of the sulfhydryl protease calotropin DI at 3.2 A resolution

The three-dimensional structure of the sulfhydryl protease calotropin DI from the madar plant, Calotropis gigantea, has been determined at 3.2 A resolution using the multiple isomorphous replacement method with five heavy atom derivatives. A Fourier synthesis based on protein phases with a mean figure of merit of 0.857 was used for model building. The polypeptide backbone of calotropin DI is folded to form two distinct lobes, one of which is comprised mainly of alpha-helices, while the other is characterized by a system of all antiparallel pleated sheets. The overall molecular architecture closely resembles those found in the sulfhydryl proteases papain and actinidin. Despite the unknown amino acid sequence of calotropin DI a number of residues around its active center could be identified. These amino acid side-chains were found in a similar arrangement as the corresponding ones in papain and actinidin. The polypeptide chain between residues 1 and 18 of calotropin DI folds in a unique manner, providing a possible explanation for the unusual inability of calotropin DI to hydrolyze those synthetic substrates that papain and actinidin act upon.

Isolation of highly active papaya peptidases A and B from commercial chymopapain

Four enzyme fractions were isolated from commercial chymopapain (EC 3.4.22.6) by chromatography on carboxymethyl cellulose CM-32 and were further purified on an agarose-mercurial column. Two fractions proved to be different forms of chymopapain B, the other two were papaya peptidase A and papaya peptidase B. The two latter enzymes were examined in detail. In contrast to previous findings, papaya peptidases exhibited high specific activity, similar to that of papain, (EC 3.4.22.2) and contained about 1 mol-SH group per mol enzyme. These results are not consistent with the idea that the essential -SH group of papaya peptidase A is 'masked' in the native state, but rather suggest that previous preparations contained a substantial amount of inactive enzyme.

Multiple forms of the asclepains. Cysteinyl proteases from milkweed

Two groups of asclepains (EC 3.4.22.7) isolated from the latex of Asclepias syriaca L. (milkweed) were each separated into five homogeneous enzymes. The members of each group are of similar amino acid composition, and leucine is the common N-terminal residue. Michaelis values are reported for each of the component cysteinyl proteases of milkweek latex, and are compared with those of analogous enzymes from other plant sources. The asclepains all catalysed the hydrolysis of insulin B chain to yield similar two-dimensional maps. The peptides produced from one such digestion were characterized and scission points were defined and compared with those for papain.

N-Terminal homology in three cysteinyl proteases from Papaya latex

Sequences to residue 17 have been determined for the three Papaya cysteinyl proteases, chymopapain and papaya peptidase A and B. Extensive homologies were found for these three enzymes and with papain and bromelain. These results suggest that the five sulphydryl enzymes discussed derive from a common ancestral gene.