Purification and characterization of a novel calcium-dependent serine proteinase secreted from malignant hamster embryo fibroblast Nil2C2

A novel serine proteinase was purified from the conditioned medium of malignant hamster embryo fibroblasts, Nil2C2. The molecular weight of the purified enzyme was estimated to be 88,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing conditions. The enzyme was split into two subunits (Mr 66,000 and 33,000) with a reducing agent. The enzyme hydrolyzed not only synthetic peptides which are susceptible to trypsin digestion but also extracellular matrix proteins such as type I and IV collagen, fibronectin and gelatin. For the digestion of these proteins, Ca2+ at millimolar concentrations was essential but Ca2+ or chelators did not affect the esterase activity for synthetic peptides. The proteolytic activity was inhibited by diisopropyl fluorophosphate (DFP) and also by phenylmethylsulfonyl fluoride. DFP was shown to bind to the 33 kDa subunit, indicating that the catalytic machinery of the enzyme is located in this subunit.     

Purification and characterization of a novel glutathione S-transferase from Atactodea striata

A novel GST isoenzyme was purified from hepatopancreas cytosol of Atactodea striata with a combination of affinity chromatography and reverse-phase HPLC. The molecular weight of the enzyme was determined to be 24 kDa by SDS-PAGE electrophoresis and 48 kDa by gel chromatography, in combination with GST information from literature revealed that the native enzyme was homodimeric with a subunit of M(r) 24 kDa. The purified enzyme, exhibited high activity towards 1-chloro-2,4-dinitrobenzene (CDNB) and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). Kinetic analysis with respect to CDNB as substrate revealed a K(m) of 0.43 mM and V(max) of 0.24 micromol/min/mg and a specific activity of 108.9 micromol/min/mg. The isoelectric point of the enzyme was 5.5 by isoelectric focusing and its optimum temperature was 38 degrees C and the enzyme had a maximum activity at approximately pH 8.0. The amino acid composition was also determined for the purified enzyme.     

Purification and characterization of an aminopeptidase from the edible basidiomycete Grifola frondosa

An aminopeptidase was purified 178-fold from an extract of Grifola frondosa by ammonium sulfate precipitation and a series of column chromatographies on phenyl-Toyopearl, Sephadex G-25, and Mono-Q. The molecular mass of the enzyme was estimated to be 27 kDa and 30 kDa by gel filtration and SDS-PAGE, respectively. The enzyme had an optimum pH of 8.5 and was stable between pH 6.0 and pH 10.5, and it also had a high level of heat stability. The enzyme was inactivated by EDTA and o-phenanthroline, and it was also strongly inhibited by bestatin, but no inhibitory effect of DFP was observed. The enzyme preferentially hydrolyzed peptides containing hydrophobic residues in the N-terminal position.     

Partial purification and characterization of NADH-glutamate synthase from faba bean (Vicia faba) root nodules

The NADH-dependent glutamate synthase (EC 1.4.1.14) from the plant fraction of N₂-fixing faba bean (Vicia faba) nodules has been purified 74-fold to a specific activity of about 3 μmol min⁻¹ mg protein⁻¹ with a final yield of 32%. The NADH-GOGAT activity was associated with a single form of the enzyme that behaved as a monomeric protein with a subunit molecular weight of 195 kDa and a native molecular weight from 222 to 236 kDa estimated by gel filtration or PAGE, respectively. The NADH-GOGAT band on SDS-PAGE was cut out and used to produce antibodies. Western blots of SDS-PAGE of crude nodule proteins revealed a 195 kDa polypeptide in root extracts but not in those of leaves or bacteroids. The antiserum also cross-reacted with a polypeptide of camparable molecular weight (195 kDa) from both amide and ureide transporting species legume nodules, indicating that some antigenic epitopes have been conserved between nodule NADH-GOGAT of different species.     

Purification and properties of Pinus taeda arginase from germinated seedlings

In germinated loblolly pine (Pinus taeda L.) seeds arginine accumulates in the seedling during its growth immediately following germination. The enzyme arginase (L-arginine amidinohydrolase, EC 3.5.3.1) is responsible for hydrolyzing this arginine into ornithine and urea. Loblolly pine arginase was purified to homogeneity from seedling cotyledons by chromatographic separation on DE-52 cellulose, Matrex Green and arginine-linked Sepharose 4B. The enzyme was purified 148-fold and a single polypeptide band was identified as arginase. The molecular mass was determined to be 140 kDa by FPLC, while the subunit size was shown to be 37 kDa by SDS-PAGE, predicting a homotetramer holoprotein. Removal of manganese from the enzyme abolishes catalytic activity, which can be restored by incubating the protein with Mn²⁺. Antibodies, raised against the arginase subunit, are able to immunotitrate arginase activity and are monospecific for arginase on immunoblots.     

Isolation and purification of an extracellular protease from a new strain of Bacillus subtilis, viz.NCIM 2711

A new extracellular protease having a prospective application in the food industry was isolated from Bacillus sUbtilis NCIM 2711 by (NH4)2SO4 precipitation from the cell broth. It was purified using DEAE-Cellulose and CM-Sephadex C-50 ion-exchange chromatography. With casein as a substrate, the proteolytic activity of the purified protease was found to be optimal at pH 7.0 and temperature 55 degrees C with Km 1.06 mg/ml. The enzyme was stable over a pH range 6.5-8.0 at 30 degrees C for 1 hr in presence of CaCl2 x 2H2O. At 55 degrees C, the enzyme retained 60% activity up to 15 min in presence of CaCl2 x 2H2O. EDTA and o-phenanthroline (OP) completely inhibited the enzyme activity while DFP, PMSF and iodoacetamide were ineffective. The enzyme was completely inhibited by Hg2+ and partially by Cd2+, Cu2+, Ni2+, Pb2+ and Fe2+. The OP inhibited enzyme could be reactivated by Zn2+ and Co2+ up to 75% and 69% respectively. It is a neutral metalloprotease showing a single band of 43 kDa on SDS-PAGE.     

Purification of CMP-N-acetylneuraminic acid synthetase from bovine anterior pituitary glands

CMP-beta-N-acetylneuraminic acid (CMP-neuNAc) is the substrate for the sialylation of glycoconjugates by sialyltransferases in microbes and higher eukaryotes. CMP-neuNAc synthetase catalyzes the formation of this substrate, CMP-neuNAc, from CTP and neuNAc. In this report we describe the purification of CMP-neuNAc synthetase from bovine anterior pituitary glands. The enzyme was purified by ion exchange, gel filtration, and affinity chromatography. The protein was homogeneous on SDS-PAGE with a molecular weight of 52 kDa, a subunit size similar to that of the E.coli K1 (48.6 kDa). The identity of the 52 kDa protein band was confirmed by native gel electrophoresis in that the position of the enzyme activity in gel slices coincided with the position of major bands in the stained gel. Photoaffinity labeling with 125I-ASA-CDP ethanolamine resulted in the modification of a 52 kDa polypeptide that was partially protected against modification by the substrate CTP. Enzyme activity in crude fractions could be adsorbed onto an immunoadsorbent prepared from antibody against the purified 52 kDa protein. Taken together these data suggest that the 52 kDa polypeptide purified by this procedure described in this report is indeed CMP-neuNAc synthetase. The active enzyme chromatographed on a gel filtration column at 158 kDa suggesting it exists in its native form as an oligomer.     

Purification and characterization of alkaline soda-bleach stable protease from Bacillus sp. APP-07 isolated from Laundromat soil

The detergent-compatible alkaline protease was produced from the bacterial strain Bacillus sp. APP-07 isolated from Laundromat soil of Solapur, Maharashtra, India. The culture was grown in 1000?ml capacity baffled flask with a working volume of 100?ml and incubated at 55?°C for 33?h on a rotary shaker. After incubation, alkaline protease was partially purified by the sequential method of acetone precipitation followed by nominal molecular weight limit (NMWL) cut-off ultrafiltration using 50?K and 10?K filters. Finally, Sephadex G-100 gel filtration chromatographic purification was performed to obtain 3.12 fold purified alkaline protease enzyme with a 66.67% final yield. The purified enzyme showed 31907.269 units (U) of enzyme activity containing 8741.718?U/mg of specific enzyme activity. The molecular weight of the enzyme was confirmed about 33.0?kDa (kDa) by the SDS-PAGE analysis. The purified enzyme was stable at higher pH and temperature range, with an optimum pH 10.5 and temperature 55?°C. The enzyme showed excellent stability and compatibility in various detergents, surfactants, bleach, and oxidizing agents. The enzyme activity enhanced in the presence of Ca²⁺, Cu²⁺, and surfactants, whereas; the phenylmethylsulphonyl fluoride (PMSF) and Diisopropyl fluorophosphate (DFP) completely inhibit the enzymatic activity, which pointed out that the enzyme affiliated to serine-centered metalloproteases family.In conclusion, the remarkable tolerance and stability of the enzyme explored the promising candidature for the several potential applications in the laundry detergents. The sustainability of the enzyme might serve several possible applications in the laundry detergents, leather industries, and other harsh industrial processes.     

A recombinant form of the catalytic subunit of phosphorylase kinase that is soluble, monomeric, and includes key C-terminal residues.

Residues 302-326 of the catalytic (gamma) subunit of phosphorylase kinase (PhK) may comprise an autoinhibitory, pseudosubstrate domain that binds calmodulin. To study this, the cDNA corresponding to rabbit muscle PhKgamma was expressed using Escherichia coli. This yielded two stable, high-activity PhKgamma forms (35 and 42 kDa by SDS-PAGE) that were smaller than an authentic sample of rabbit muscle PhKgamma (45 kDa by SDS-PAGE). Each recombinant form was purified to homogeneity. The N-terminal sequence of the larger, 42-kDa form (pk42) matched that of the rabbit muscle enzyme. This suggested that pk42 consisted of PhKgamma residues 1-362, including the putative calmodulin-binding, autoinhibitory domain. Kinetic parameters obtained for pk42 were like those previously reported for the intact gamma subunit. This implied that the lack of 25 PhKgamma C-terminal residues did not affect phosphorylase kinase activity, but greatly improved enzyme stability. An additional 60 residues were removed from the C-terminus of pk42 using the protease m-calpain. This increased the kinase activity 1.5-fold. Consistent with this, the activity of a mutant PhKgamma that consisted of residues 1-300, denoted gamma1-300, was like that of the m-calpain-treated enzyme. Therefore, although the effect was small, some influence by the C-terminus of pk42 was noted. Moreover, when pk42 was incubated with ATP alone, a C-terminal threonine residue became phosphorylated. Although the influence of this autophosphorylation cannot be inferred from this data, it was evidence that the C-terminus accessed the enzyme's active site. Taken together, these data imply that pk42 will be useful to study phosphorylase kinase structure/activity relationships.     

A 27.368 kDa retinal reductase in New Zealand white rabbit liver cytosol encoded by the peroxisomal retinol dehydrogenase-reductase cDNA: purification and characterization of the enzyme.

We obtained a full-length cDNA based on a sequence deposited in GenBank (accession No. AB045133), annotated as rabbit peroxisomal NADP(H)-dependent retinol dehydrogenase-reductase (NDRD). The rabbit NDRD gene, like its mouse and human homologs, harbors 2 initiation sites, one of which theoretically encodes a 29.6 kDa protein with 279 amino acids, and the other encodes a 27.4 kDa protein with 260 amino acids. The purification of a rabbit cytosolic retinol oxidoreductase with a subunit molecular mass of 34 kDa and an N terminus that is not completely identical to that of NDRD, has been reported. An enzyme responsible for the all-trans retinal reductase activity in the liver cytosol of New Zealand white rabbit was purified to homogeneity using differential centrifugation and successive chromatographic analyses. The subunit molecular mass of the purified enzyme, revealed by SDS-PAGE, was approximately 27 kDa. The intact molecular mass, measured by MALDI-TOF mass spectrometry, was 27.368 kDa. The 60 kDa relative mobility observed in size-exclusion chromatography indicates that the native protein probably exists as a dimer. The purified enzyme was positively confirmed to be the product of NDRD by peptide mass fingerprinting, tandem mass spectrometry, and N-terminal sequencing. Taken together, the results suggested that the native protein is truncated at the N terminus.     

Highly stable glycosylated serine protease from the medicinal plant Euphorbia milii

A serine protease, named as "Milin" was purified to homogeneity from the latex of Euphorbia milii, a medicinal plant of Euphorbiaceae family. The molecular mass (SDS-PAGE), optimum pH and temperature of the enzyme were 51kDa, pH 8.0 and 60 degrees C, respectively. Milin retains full proteolytic activity over a wide range of pH (5.5-12) and temperature (up to 65 degrees C) with casein and azoalbumin as substrates. The activity of milin is inhibited by serine proteases inhibitors like PMSF, APMSF and DFP, but not by any other protease inhibitors such as E-64 and PCMB. Like the other serine proteases from the genus Euphorbia, the activity of milin was not inhibited by the proteinaceous inhibitor soyabean trypsin inhibitor (SBTI) even at very high concentrations that is naturally present in plants. The specific extinction coefficient (epsilon(280 nm)(1%)), molar extinction coefficient (a(m)) and isoelectric point of the enzyme were found to be 29, 152,500 M(-1) cm(-1) and pH 7.2, respectively. The enzyme is a glycoprotein with detectable carbohydrate moiety (7-8%) in its constitution, which is essential for the activity. The numbers of tryptophan, tyrosine and cysteine residues in the sequence of milin were estimated chemically and are 23, 14 and 14, respectively. Of the 14-cysteine residues, 12 constituted 6-disulfide linkages while two are free cysteines. The N-terminal sequence (first 12 amino acid residues) was determined and does not match with any sequence of known plant serine proteases. Perturbation studies by temperature, pH and chaotropes of the enzyme also reveal its high stability as seen by CD, fluorescence and proteolytic activity. Thus, this serine protease may have potential applications in food industry.     

Purification and characterization of an intracellular heat-stable proteinase (pernilase) from the marine hyperthermophilic archaeon Aeropyrum pernix K1

A novel intracellular serine proteinase from the marine aerobic hyperthermophilic archaeon Aeropyrum pernix K1 (JCM 9820) that we designated pernilase was purified by ammonium sulfate precipitation, anionic-exchange chromatography, affinity chromatography, and gel filtration chromatography. The purified enzyme was composed of a single polypeptide chain with a molecular mass of 50 kDa as determined by SDS-PAGE. The proteinase had a broad pH profile (pH 5–10) with an optimum pH of 9.0 for peptide hydrolysis. The optimum temperature for enzyme activity was 90°C. The enzyme was strongly inhibited by diisopropyl fluorophosphate (DFP) and phenylmethyl sulfonylfluoride (PMSF), suggesting that it corresponds to a serine proteinase. The enzyme was highly resistant to the reducing agents dithiothreitol and 2-mercaptoethanol but sensitive to the denaturing reagents guanidine-HCl and urea and also to the detergent sodium dodecyl sulfate (SDS). Pernilase showed high substrate specificity for Boc-Leu-Gly-Arg-MCA peptide. Thermostability of this enzyme showed half-lives of 85 min at 100°C and 12 min at 110°C. Received September 24, 1997 / Accepted May 20, 1998     

Purification of diacylglycerol kinase from Microsporum gypseum and its phosphorylation by the catalytic subunit of protein kinase A

Diacylglycerol (DG) kinase (EC 2.7.1.107) was purified to homogeneity from the soluble extract of Microsporum gypseum, a dermatophyte. Purified enzyme showed a final specific activity of 2172 pmol/min/mg protein and its apparent molecular weight on SDS-PAGE was found to be 93 kDa. The activity of purified enzyme was inhibited in a dose-dependent manner in the presence of DG-kinase inhibitor (D5919, Sigma). DG-kinase activity was found to be stimulated in the presence of phosphatidylcholine, phosphatidylethanolamine, and cardiolipin while the activity was alleviated in the presence of phosphatidic acid and arachidonic acid. Kinase activity was partially inhibited when assayed after prior treatment with alkaline phosphatase. Treatment of DG-kinase with the catalytic subunit of protein kinase A (PKA)-stimulated DG-kinase activity in a dose-dependent manner. Incubation of DG-kinase with the catalytic subunit of PKA led to the phosphorylation of DG-kinase as revealed by autoradiography. The phosphorylated band disappeared completely in the presence of specific PKA inhibitor. Increased activity of DG-kinase on incubation with the catalytic subunit of PKA was possibly due to the phosphorylation of the former by the latter. Whether this in vitro phosphorylation and activation of DG-kinase occurs under physiological conditions remains to be elucidated.     

Glucose-fructose oxidoreductase, a periplasmic enzyme of Zymomonas mobilis, is active in its precursor form

Abstract Glucose-fructose oxidoreductase (GFOR) is a periplasmic enzyme of the ethanologenic, Gram-negative bacterium Zymomonas mobilis . It contains tightly bound NADP⁺ as cofactor. In Z. mobilis GFOR-recombinant strains, a precursor form of GFOR was accumulated. To assay the preGFOR for its NADP(H) content and enzymatic activity, it was purified from an overproducing strain. Using SDS-PAGE, the precursor subunit size was determined to approximately 45 kDa (compared with a 40 kDa subunit size for the mature GFOR subunit). The N-terminal amino acid sequence of the precursor was determined. The N-terminal residues of the GFOR matched with the signal sequence from the DNA sequence of the gene gfo . The precursor form of GFOR was enzymatically active and contained the cofactor NADP(H).     

Purification and characterization of glutathione peroxidase from human blood platelets. Age-related changes in the enzyme

Platelet glutathione peroxidase (GPx) is known to play a pivotal role in controlling the level of lipid hydroperoxides, especially those resulting from the 12-lipoxygenase activity. GPx was purified fromm the cell cytosol by more than 700-fold using an exchange chromatography, FPLP, gel filtration and covalent fixation. Isoelectric focusing revealed a peak activity at pH 5.1. The molecular mass of enzyme was found between 90 and 100 kDa by gel filtration, and was approximating at 23kDa by SDS-PAGE. A polyclonal antibody raised against commercial bovine erthrocyte GPx recognized the human platelet enzyme. It is concluded that human platelet GPx is likely a homotetramer of 92 kDa as described for most sources. We have also found that the decreased platelet GPx activity observed in platelets from elederly people is associated with a lower content of the immunoreactive enzyme.     

The generation of big-endothelin (1-22) (endothelin-valine) from big-endothelin in the soluble fraction of porcine lung.

The degradation of big-endothelin (big-ET) in the soluble fraction of porcine lung was investigated. The degradation in the presence of p-chloromercuribenzoate (PCMB), pepstatin A, and EDTA resulted in the accumulation of two newly-formed fragments, big-ET (23-39) and big-ET (1-22), the latter called endothelin-valine (ET-Val). The generation of the two fragments was inhibited by diisopropylfluorophosphate (DFP). The enzyme responsible, called ET-Val-generating endopeptidase, was isolated from porcine lung by a procedure including chromatographies on columns of DEAE-cellulose, hydroxylapatite, Mono Q, p-mercuribenzoate-Sepharose, and Superose 6. The molecular weight of the enzyme was 140,000 and the pH optimum of the activity was 7.0. The activity was strongly inhibited by DFP, but scarcely inhibited by PCMB, EDTA, and pepstatin A. Thus, the isolated enzyme was classified as a serine protease cleaving big-ET at the Val22-Asn23 bond.     

Purification and characterization of cAMP dependent protein kinase from Microsporum gypseum

A cyclic AMP dependent protein kinase (PKA), its regulatory (R) and catalytic (C) subunits were purified to homogeneity from soluble extract of Microsporum gypseum. Purified enzyme showed a final specific activity of 277.9 nmol phosphate transferred min(-1) mg protein(-1) with kemptide as substrate. The enzyme preparation showed two bands with molecular masses of 76 kDa and 45 kDa on sodium dodecyl polyacrylamide gel electrophoresis. The 76 kDa subunit was found to be the regulatory (R) subunit of PKA holoenzyme as determined by its immunoreactivity and the isoelectric point of this subunit was 3.98. The 45 kDa subunit was found to be the catalytic (C) subunit by its immunoreactivity and phosphotransferase activity. Gel filtration using Sepharose CL-6B revealed the molecular mass of PKA holoenzyme to be 240 kDa, compatible with its tetrameric structure, consisting of two regulatory subunits (76 kDa) and two catalytic subunits (45 kDa). The specificity of enzyme towards protein acceptors in decreasing order of phosphorylation was found to be kemptide, casein, syntide and histone IIs. Purified enzyme had apparent K(m) values of 71 microM and 25 microM for ATP and kemptide, respectively. Phosphorylation was strongly inhibited by mammalian PKA inhibitor (PKI) but not by inhibitors of other protein kinases. The PKA showed maximum activity at pH 7.0 and enzyme activity was inhibited in the presence of N-ethylmaleimide (NEM) which shows the involvement of sulfhydryl groups for the activity of PKA. PKA phosphorylated a number of endogenous proteins suggesting the multifunctional role of cAMP dependent protein kinase in M. gypseum. Further work is under progress to identify the natural substrates of this enzyme through which it may regulate the enzymes involved in phospholipid metabolism.     

Purification and properties of ornithine carbamoyltransferase from loggerhead turtle liver

Ornithine carbamoyltransferase has been purified from the liver of the loggerhead turtle Caretta caretta by a single-step procedure using chromatography on an affinity column to which the transition-state analogue, delta-N-(phosphonoacetyl)-L-ornithine (delta-PALO), was covalently bound. The procedure employed yielded an enzyme which was purified 373-fold and was judged to be homogeneous by nondenaturing and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed a specific activity of 224. The molar mass of the C. caretta enzyme was approximately 112 kDa, the single band obtained by SDS-PAGE indicated a subunit molar mass of 39.5 kDa; hence, the enzyme is a trimer of identical subunits. It catalyzes an ordered sequential mechanism in which carbamoyl phosphate binds first, followed by L-ornithine. The Michaelis constants were 0.858 mM for L-ornithine and 0.22 mM for carbamoyl phosphate, the dissociation constant of the enzyme-carbamoyl phosphate complex was 0.50 mM.     

Molecular cloning,purification, and characterization of a superoxide dismutase from a fast-growing <Emphasis Type="Italic">Mycobacterium</Emphasis> sp. Strain JC1 DSM 3803

A cytosolic superoxide dismutase (SOD) was purified and characterized from a fast-growing Mycobacterium sp. strain JC1 DSM 3803 grown on methanol. The native molecular weight of the purified SOD was estimated to be 48 kDa. SDS-PAGE revealed a subunit of 23 kDa, indicating that the enzyme is a homodimer. The enzyme activity was inhibited by H₂O₂ and azide. The purified SOD contained 1.12 and 0.56 g-atom of Mn and Fe per mol of enzyme, respectively, suggesting that it may be a Fe/Mn cambialistic SOD. The apo-SOD reconstitution study revealed that Mn salts were more specific than Fe salts in the SOD activity. The gene encoding the SOD was identified from the JC1 cosmid genomic library by PCR screening protocol. The cloned gene, sodA, had an open reading frame (ORF) of 624 nt, encoding a protein with a calculated molecular weight of 22,930 Da and pi of 5.33. The deduced SodA sequence exhibited 97.6% identity with that of Mycobacterium fortuitum Mn-SOD and clustered with other mycobacterial Mn-SODs. A webtool analysis on the basis of SOD sequence and structure homologies predicted the SOD as a tetrameric Mn-SOD, suggesting that the protein is a dimeric Mn-SOD having tetramer-specific sequence and structure characteristics.     

Purification and properties of soman-hydrolyzing enzyme from human liver

A soman-hydrolyzing enzyme (soman-ase) was purified from human liver. The humansomanase is capable of hydrolyzing pinacolyl meth-ylphosphonofluoridate (soman), diisopropylphos-phorofluoridate (DFP), and ethyl-N-dimethyl phos-phoramidocyanidate (Tabun) with P–F or P–CNbonding, but not ethyl (S-2-diisopropylaminoethyl)methylphosphonothiolate (VX) and diethyl-p -nitro-phosphenylphosphate (paraoxon) with P–S or P–O bonding. The somanase has been purified 1570-fold with a specific activity of 41.4 μmol/min/mg protein. Its molecular weight is around 58 kDa determined by SDS-PAGE. The somanase could be stimulated by the divalent cations Mn⁺², Mg⁺², and Co⁺², where Co⁺² activation is the highest. The requirement of disulfide bonds for the enzyme activity was demonstrated by the inhibition effect of DTT. © 1998 John Wiley & Sons, Inc. J Biochem Toxicol 12: 213–217, 1998