Phosphodiesterase from the venom of Crotalus ruber ruber

Phosphodiesterase was isolated from the venom of Crotalus ruber ruber from the U.S.A. using the gel filtration on a Sephadex G-75 column, followed by anion or cation exchange chromatography. Phosphodiesterase was homogeneous as established by a single band on acrylamide gel electrophoresis and isoelectric focusing electrophoresis. Phosphodiesterase activity was inhibited by ethylenediamine tetraacetic acid (EDTA), o-phenanthroline, thioglycolic acid or p-chloromercuribenzoate (PCMB), but not by soybean trypsin inhibitor (SBTI) or benzamidine. The molecular weight of this enzyme was determined to be approx. 98,000 and the isoelectric point was found to be pH 10.5 by isoelectric focusing with carrier ampholyte. This enzyme contained 1.04 mol zinc per mol. The Michaelis constant (Km) of this enzyme for p-nitrophenyl thymidine-5'-phosphate and inhibition constant (Ki) for PCMB were found to be 8.3 X 10(-3) and 1.2 X 10(-2) M, respectively.     

Proline iminopeptidase from Bacillus coagulans: purification and enzymatic properties

Proline iminopeptidase [EC 3.4.11.5] was purified about 2,700-fold from cell-free extract of Bacillus coagulans by a series of column chromatographies on DEAE-Toyopearl, PCMB-T-Sepharose, and hydroxyapatite, and gel filtration on Sephadex G-150. The purified enzyme was homogeneous as judged by disc gel electrophoresis. The enzyme was most active at pH 7.3 with Pro-beta-naphthylamide (Pro-2-NNap) as the substrate, and hydrolyzed Pro-X (X = amino acid including proline, peptide, amide, and arylamide) bonds when the proline residue was at the amino terminus. Pro-D-amino acid bonds were also susceptible to the enzyme. The enzyme was completely inhibited by p-chloromercuribenzoate (PCMB) and partially by proline but not by metal chelators, diisopropylphosphorofluoridate (DFP), or phenylmethanesulfonyl fluoride (PMSF). The enzyme inactivated with PCMB was reactivated by incubation with 2-mercaptoethanol. These results and the chromatographic profile on PCMB-T-Sepharose suggest that the enzyme is a sulfhydryl enzyme. The isoelectric point of the enzyme was 4.0, and the molecular weight of the enzyme was estimated to be 40,000 by gel filtration on Sephadex G-100 and 35,000 by sodium dodecyl sulfate (SDS) gel electrophoresis, indicating that the enzyme exists as a monomer.     

Proline iminopeptidase from Bacillus megaterium: purification and characterization

Proline iminopeptidase [EC 3.4.11.5] was purified about 1,700-fold from cell free extract of Bacillus megaterium by a series of column chromatographies on DEAE-Toyopearl, PCMB-T-Sepharose and hydroxyapatite, and gel filtration on Toyopearl FW-55. The purified enzyme still contained a minor contaminant as judged by disc gel electrophoresis. The enzyme was most active at pH 7.0 with Pro-beta-naphthylamide (Pro-2-NNap) as the substrate, and hydrolyzed Pro-X (X = amino acid, peptide, amide, and arylamide) bonds when the proline residue was at the amino terminal. The enzyme was completely inactivated by p-chloromercuribenzoate (PCMB), but was not inhibited by metal chelators, diisopropylphosphorofluoridate (DFP) and phenylmethanesulfonyl fluoride (PMSF). The enzyme inactivated with PCMB was reactivated by adding 2-mercaptoethanol. From this result and the chromatographic profile on PCMB-T-Sepharose, the enzyme seems to be a sulfhydryl enzyme. The isoelectric point of the enzyme was 4.0. The molecular weight of the enzyme was estimated to be 58,000 by gel filtration on Toyopearl and 60,000 by sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme is a monomer.     

Purification and characterization of an acidic amino acid specific endopeptidase of Streptomyces griseus obtained from a commercial preparation (Pronase)

A protease was purified 163-fold from Pronase, a commercial product from culture filtrate of Streptomyces griseus, by a series of column chromatographies on CM-Toyopearl (Fractogel), Sephadex G-50, hydroxyapatite, and Z-Gly-D-Phe-AH-Sepharose 4B using Boc-Ala-Ala-Pro-Glu-pNA as a substrate. The final preparation was homogeneous by polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and gel isoelectric focusing. Studies on the substrate specificity with peptide p-nitroanilides revealed that this protease preferentially hydrolyzed peptide bonds on the carbonyl-terminal side of either glutamic acid or aspartic acid. It was most active at pH 8.8 for the hydrolysis of Boc-Ala-Ala-Pro-Glu-pNA. The molecular weight of the protease was estimated to be 20,000 by gel filtration on Sepharose 6B using 6 M guanidine hydrochloride as an eluent, and 22,000 by SDS-PAGE in the presence of 2-mercaptoethanol. The isoelectric point of the enzyme was 8.4. The enzyme was inactivated by diisopropyl phosphofluoridate (DFP) but not by p-chloromercuribenzoate (PCMB) or EDTA.     

Post-proline cleaving enzyme (prolyl endopeptidase) from bovine brain

A post-proline cleaving enzyme [prolyl endopeptidase, EC 3.4.21.26] was purified about 3,700-fold from an extract of bovine brain by a series of column chromatographies on DEAE-Sephadex, hydroxyapatite and PCMB-T-Sepharose, and gel filtration on Sephadex G-200 using N-carbobenzoxy-Gly-Pro-beta-naphthylamide (Z-Gly-Pro-2-NNap), thyrotropin releasing hormone (TRH) and oxytocin as substrates. The purified enzyme appeared homogeneous as judged by disc gel and SDS gel electrophoreses. The enzyme was most active at pH 7.5 and 7.2 with Z-Gly-Pro-2-NNap and TRH, respectively, and hydrolyzed peptide bonds involving Pro-X (X=amino acid, peptide, ester and amide) bonds of synthetic substrates, oxytocin, vasopressin, neurotensin, substance P, tuftsin, bradykinin, and insulin B chain. However, the enzyme was inert toward collagen, gelatin, and casein. The enzyme was completely inactivated by diisopropylphosphorofluoridate (DFP), Z-Gly-Pro-chloromethyl ketone and p-chloromercuribenzoate (PCMB), while it was not inhibited by phenylmethane sulfonylfluoride (PMSF) or metal chelators. Determination of the amino acid composition revealed that the enzyme contained 25 half-cystines. Modification of three cysteine residues of the enzyme by PCMB led to complete inactivation. The isoelectric point of the enzyme was 4.8, and the molecular weight was estimated to be 76,000 by ultracentrifugal analysis and 75,000-74,000 by both gel filtration and sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme is present as a monomer. These results indicate that the post-proline cleaving enzyme from bovine brain is very similar to those previously purified from lamb brain and kidney in its enzymatic properties, substrate specificity and physicochemical properties, in sharp contrast with the results obtained by Tate, who reported that the bovine brain prolyl endopeptidase was inert toward oxytocin, vasopressin and bradykinin.     

Beta-fibrinogenase from the venom of Agkistrodon p. piscivorus

1. Beta-fibrinogenase was isolated from the venom of Agkistrodon p. piscivorus by column chromatography on Sephadex G-100, DEAE-Sephacel and by chromatofocusing, with a yield of 2.5 mg of purified enzyme from 1 g of crude venom. 2. The enzyme was homogeneous by SDS and non-SDS disc electrophoresis on polyacrylamide gel at pH 8.3. 3. Beta-fibrinogenase is a glycoprotein possessing both TAME hydrolase and kinin-releasing activities. 4. A mol. wt of approximately 33,500 and an isoelectric point 4.5 was determined. 5. The enzyme is stable to heat treatment and to a pH range of 2-10. 6. Beta-fibrinogenase activity is inactivated by DFP, suggesting that serine is involved in the enzymatic activity. 7. The Michaelis constant (Km) of this enzyme for TAME and inhibition constant (Ki) for DFP were found to be 7.04 X 10(-3) and 4.13 X 10(-3) M, respectively.     

Purification and properties of an enzyme catalyzing the splitting of carbon-mercury linkages from mercury-resistant Pseudomonas K-62 strain. I. Splitting enzyme 1.

An enzyme (S-1) which catalyzes the splitting of carbon-mercury linkages of organomercury compounds was purified about 24-fold from the cell-free extract of mercury-resistant Pseudomonas K-62 strain by treatment with streptomycin, precipitation with ammonium sulfate, and successive chromatography on Sephadex G-150, DEAE-Sephadex, and DEAE-cellulose. A purified preparation of the enzyme showed a single band on polyacrylamide gel electrophoresis, and was colorless. The molecular weight of the enzyme was estimated to be 19,000, and Km was 5.3 X 10(-5) M for p-chloromercuribenzoic acid (PCMB). The temperature and pH optimum for the reaction were 50degrees and 7.0, respectively. The enzyme was capable of catalyzing the decomposition of methylmercuric chloride (MMC), ethylmercuric chloride (EMC), phenylmercuric acetate (PMA), and PCMB in the presence of a sulfhydryl compound to form a mercuric ion plus methane, ethane, benzene, or benzoic acid, respectively. The mercuric ion thus formed was reduced to metallic mercury by metallic mercury-releasing enzyme (MMR-enzyme).     

Purification and properties of pig liver kynureninase.

Kynureninase [L-kynurenine hydrolase, EC 3.7.1.3] was purified from pig liver by a procedure including DEAE-cellulose chromatography, hydroxyapatite chromatography, ammonium sulfate fractionation, DEAE-Bio Gel chromatography, Sephacryl S-200 gel filtration, kynurenine-Sepharose affinity chromatography, and Sephadex G-200 gel filtration. The enzyme was found to be homogeneous by the criterion of disc-gel electrophoresis. The enzyme has a molecular weight of about 100,000 and exhibits absorption maxima at 280 and 420 nm. The optimum pH and the isoelectric point of the enzyme are 8.5 and 5.0, respectively. The Michaelis constants were determined to be as follows: L-kynurenine, 7.7 X 10(-4) M; L-3-hydroxykynurenine, 1.3 X 10(-5) M; and pyridoxal 5'-phosphate, 1.8 X 10(-6) M. L-3-Hydroxykynurenine is hydrolyzed more rapidly than L-kynurenine; the liver enzyme can be regarded as a 3-hydroxy-kynureninase.     

Isolation and purification of restriction endonuclease SacI from Streptomyces achromogenes ATCC 12767

A procedure for isolation and purification of restriction endonuclease Sac I from Streptomyces achromogenes ATCC 12767 is proposed. It allows to obtain an electrophoretically homogeneous enzyme preparation with the purification degree 1097 and the enzyme yield by activity 3.7%. The molecular weight of SacI was found to be 52,000 +/- 5,000 D, and isoelectric point 6.2. The enzyme consists of two subunits, which was found by polyacrylamide gel electrophoresis under denaturing conditions. Km and Vmax values were determined for the enzymatic reaction; they are equal to 4.6 X 10(-9) M and 9.19 X 10(-10) M/min, respectively.     

Purification and characterization of human seminal plasma acid phosphatase

A 81-fold purification of human seminal plasma acid phosphatase was obtained by a three-step procedure, involving ammonium sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. Homogeneity of the preparation during purification steps was tested by polyacrylamide gel electrophoresis and only one major band was obtained after the final step. The pH optimum for the activity of the purified enzyme was 5.6 and thermal stability was obtained even up to 40 degrees C. PNPP was the most specific synthetic substrate. The Km of purified seminal acid phosphatase towards PNPP was 1.5 X 10(-3) M. Among the metal ions tested, Hg+2 showed an I50 value of 4.2 X 10(-7) M. Studies with PCMB, PMSF and EDTA did not show any inhibition, whereas NaF and L(+)tartrate, at 1 mM concentration, inhibited the enzyme by 95% and 85%, respectively.     

Purification and properties of the nuclease inhibitor of Aspergillus oryzae and kinetics of its interaction with crystalline nuclease O.

A nuclease inhibitor found in the mycelia of Aspergillus oryzae has been purified 158,000-fold by ammonium sulfate precipitation, chromatography on Sephadex G-75, DEAE-Sephadex A-50 and Bio-Gel p-60 columns, preparative disc electrophoresis on acrylamide gel, and electrofocusing in ampholite. The purified inhibitor is nearly homogeneous as judged by disc electrophoresis. It shows a typical ultraviolet absorption curve for protein, and the inhibitory activity is inactivated by chymotrypsin. The inhibitor and nuclease O (EC 3.1.4.9, a crystalline enzyme from the mycelia of the same organism) form a stable enzyme inhibitor complex. The molecular weights of nuclease O, the inhibitor and the enzyme inhibitor complex are estimated to be 46,000, 22,000 and 73,000 respectively, by Sephadex G-100 gel filtration. The isoelectric points of the enzyme and the inhibitor are 10.0 and 4.09, respectively, as determined by electrofocusing in ampholite. The inhibition is noncompetitive, and the inhibitor constant (K1) is 3.2 X 10(-12) M, whereas the Michaelis constant (Km) for DNA is 2.2 X 10(-8) M. The inactive enzyme-inhibitor complex is reactivated by chymotrypsin through inactivation of the inhibitor. The reactivated enzyme can be inactivated again by the inhibitor, which shows that desensitization of the enzyme does not occur by the action of chymotrypsin.     

Purification and properties of glucoamylase from Endomycopsis sp. 20-9]

Homogenous yeast (Endomycopsis sp. 20-9) glucoamylase was isolated from cultural medium. The homogeneity of the enzyme preparation is demonstrated by means of polyacrylamide gel disc electrophoresis, isofocusing and ultracentrifugation. Amino acid composition, molecular weight (53 000), sedimentation constant (4.3S) and isoelectric point (pI 3.80-3.82) of the enzyme are determined. Glucoamylase is found to be glucoprotein.     

Purification and characterization of phosphoglycerate mutase from methanol-grown Hyphomicrobium X and Pseudomonas AM1.

Phosphoglycerate mutase has been purified from methanol-grown Hyphomicrobium X and Pseudomonas AMI by acid precipitation, heat treatment, ammonium sulphate fractionation, Sephadex G-50 gel filtration and DEAE-cellulose column chromatography. The purification attained using the Hyphomicrobium X extract was 72-fold, and using the Pseudomonas AMI extract, 140-fold. The enzyme purity, as shown by analytical polyacrylamide gel electrophoresis, was 50% from Hyphomicrobium X and 40% from Pseudomonas AMI. The enzyme activity was associated with one band. The purified preparations did not contain detectable amounts of phosphoglycerate kinase, phosphopyruvate hydratase, phosphoglycerate dehydrogenase or glycerate kinase activity. The molecular weight of the enzymic preparation was 32000 +/- 3000. The enzyme from both organisms was stable at low temperatures and, in the presence of 2,3-diphosphoglyceric acid, could withstand exposure to high temperatures. The enzyme from Pseudomonas AMI has a broad pH optimum at 7-0 to 7-6 whilst the enzyme from Hyphomicrobium X has an optimal activity at pH 7-3. The cofactor 2,3-diphosphoglyceric acid was required for maximum enzyme activity and high concentrations of 2-phosphoglyceric acid were inhibitory. The Km values for the Hyphomicrobium X enzyme were: 3-phosphoglyceric acid, 6-0 X 10(-3) M: 2-phosphoglyceric acid, 6-9 X 10(-4) M; 2,3-diphosphoglyceric acid, 8-0 X 10(-6) M; and for the Pseudomonas AMI ENzyme: 3-4 X 10(-3) M, 3-7 X 10(-4) M and 10 X 10(-6) M respectively. The equilibrium constant for the reaction was 11-3 +/- 2-5 in the direction of 2-phosphoglyceric acid to 3-phosphoglyceric acid and 0-09 +/- 0-02 in the reverse direction. The standard free energy for the reaction proceeding from 2-phosphoglyceric acid to 3-phosphoglyceric acid was -5-84 kJ mol(-1) and in the reverse direction +5-81 kJ mol(-1).     

Comparative study of Agkistrodon acutus venoms from China and Taiwan

Three hemorrhagic toxins (Ac1-, Ac2- and Ac3-proteinases) were isolated from the lyophilized venom of Agkistrodon acutus from China using gel filtration on a Sephadex G-75 column, followed by chromatography on diethylaminoethyl (DEAE)-Sephadex A-50, DEAE-Sephacel and DEAE-cellulose. Homogeneity was established by the formation of a single band in acrylamide gel electrophoresis, isoelectric focusing and sodium dodecyl sulfate (SDS) acrylamide gel electrophoresis. Three hemorrhagic toxins possessed both lethal and proteolytic activities. These activities were inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol (beta-aminoethyl)N,N,N',N'-tetraacetic acid (EGTA), o-phenanthroline or cysteine, but not by soybean trypsin inhibitor (SBTI), p-chloromercuribenzoate (PCMB) or diisopropyl fluorophosphate (DFP). Molecular weight of hemorrhagic toxins (Ac1-, Ac2- and Ac3-proteinases) were determined to be 24,500, 25,000 and 57,000, respectively. It was found that hemorrhagic toxins have considerable similarity to hemorrhagic toxins isolated by Nikai et al. (1977) and Sugihara et al. (1978, 1979), but Ac2- and Ac3-proteinases from China and Taiwan are electrophoretically unrelated.     

Purification and characterization of acid trehalase from the yeast suc2 mutant

Acid trehalase was purified from the yeast suc2 deletion mutant. After hydrophobic interaction chromatography, the enzyme could be purified to a single band or peak by a further step of either polyacrylamide gel electrophoresis, gel filtration, or isoelectric focusing. An apparent molecular mass of 218,000 Da was calculated from gel filtration. Polyacrylamide gel electrophoresis of the purified enzyme in the presence of sodium dodecyl sulfate suggested a molecular mass of 216,000 Da. Endoglycosidase H digestion of the purified enzyme resulted after sodium dodecyl sulfate gel electrophoresis in one distinct band at 41,000 Da, representing the mannose-free protein moiety of acid trehalase. The carbohydrate content of the enzyme was 86%. Amino acid analysis indicated 354 residues/molecule of enzyme including 9 cysteine moieties and only 1 methionine. The isoelectric point of the enzyme was estimated by gel electrofocusing to be approximately 4.7. The catalytic activity showed a maximum at pH 4.5. The activity of the enzyme was not inhibited by 10 mM each of HgCl2, EDTA, iodoacetic acid, phenanthrolinium chloride or phenylmethylsulfonyl fluoride. There was no activation by divalent metal ions. The acid trehalase exhibited an apparent Km for trehalose of 4.7 +/- 0.1 mM and a Vmax of 99 mumol of trehalose min-1 X mg-1 at 37 degrees C and pH 4.5. The acid trehalase is located in the vacuoles. The rabbit antiserum raised against acid trehalase exhibited strong cross-reaction with purified invertase. These cross-reactions were removed by affinity chromatography using invertase coupled to CNBr-activated Sepharose 4B. Precipitation of acid trehalase activity was observed with the purified antiserum.     

Demonstration of two molecular forms of dipeptidyl peptidase IV in normal human serum

The heterogeneity of dipeptidyl peptidase IV (EC 3.4.14.5) was investigated in normal human serum. Thin-layer analytical isoelectric focusing revealed the presence of multiple molecular forms of the enzyme, their isoelectric points being in the pH range of 3.30-4.25. The maximum of enzyme activity appeared around pH 3.50. After treatment with neuraminidase the pI shifted to 4.70-5.40 with two maxima at pH 5.00 and 5.15. The Triton X-100 solubilized as well as the papain-treated-Triton X-100 solubilized enzyme from the whole human adult jejunal biopsy were also found to be heterogeneous. They focused--both before and after neuraminidase treatment--at pH values different from those of the enzyme of normal human serum. There was almost no pI shift after neuraminidase treatment of the intestinal enzyme from adult enterobiopsy. Electrophoresis in continuous polyacrylamide gradient gels as well as gel chromatography on Bio-Gel A-1.5m revealed two molecular forms of dipeptidyl peptidase IV in normal human serum. The estimated relative molecular mass of the major enzyme form was 250 000 in both the separation techniques used. On the other hand, the apparent relative molecular mass of the minor enzyme form was 450 000 as assessed by gradient gel electrophoresis, and 550 000, when estimated by gel chromatography. The Km values for glycyl-L-proline-4-nitroanilide as substrate with the major and minor forms of the serum enzyme were 1.60 +/- 0.39 X 10(-4) mol/l and 1.60 +/- 0.13 X 10(-4) mol/l, respectively. Our results indicate that the dipeptidyl peptidase IV in normal human serum is a heterogeneous enzyme as far as its charge and molecular size are concerned.     

Purification and characterization of peptidylarginine deiminase from rabbit skeletal muscle

The preceding paper described the identification and some properties of peptidylarginine deiminase, which catalyzes the deimination of arginyl residues in protein, from rabbit skeletal muscle, kidney, brain, and lung. In the present work we purified peptidylarginine deiminase from rabbit skeletal muscle with a 16% yield by 7 steps. The purification involved ion-exchange chromatography on DEAE-Sephacel, gel filtration on Bio-Gel A-0.5 m, and affinity chromatography on soybean trypsin inhibitor-Sepharose 4B and aminohexyl-Sepharose 4B. The purified enzyme was homogeneous on polyacrylamide gel electrophoresis with and without sodium dodecyl sulfate. The molecular weight of the enzyme was estimated to be about 83,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and 130,000-140,000 by gel filtration on Sephadex G-200. The isoelectric point was 5.3 and the amino acid composition was also determined. The enzyme preferably catalyzed the formation of citrulline derivatives from arginine derivatives in which both the amino and carboxyl groups were substituted and showed the highest activity towards Bz-L-Arg-O-Et among the arginine derivatives tested. The Km value for Bz-L-Arg-O-Et was found to be 0.50 X 10(-3) M. The enzyme also showed marked activities towards native protein substrates, such as protamine sulfate, soybean trypsin inhibitor, histone and bovine serum albumin.     

Purification and characterization of phytase from cotyledons of germinating soybean seeds

Soybean phytase (myo-inositol-hexakisphosphate phosphohydrolase; EC 3.1.3.8) was purified from 10-day-old germinating cotyledons using a four-step purification scheme. Phytase was separable from the major acid phosphatase present, and stained as a minor band of the three acid phosphatases detectable by activity staining after gel electrophoresis. The purified enzyme exhibited two closely migrating bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of approximately 59 and 60 KDa. The molar extinction coefficient of the enzyme at 280 nm was estimated to be 7.5 X 10(4) M-1 cm-1. The isoelectric point of phytase, as judged by the elution profile on chromatofocusing, was about 5.5. The enzyme was totally absorbed to a Procion Red HE3B column and eluted as a single protein component at a salt concentration of 250-300 mM. The enzyme possessed a high affinity for phytic acid (apparent Km = 48 microM), and was strongly inhibited by phosphate (apparent Ki = 18 microM), vanadate, and fluoride. Characteristic of other plant phytases, the pH and temperature optima were 4.5-4.8 and 55 degrees C, respectively.     

Preparative isoelectric focusing in ampholine electrofocusing columns versus immobiline polyacrylamide gel for the purification of biologically active leukoregulin

Preparative vertical and rotating horizontal (Rotofor) ampholine column and immobiline flat bed polyacrylamide gel isoelectric focusing were evaluated for the isolation of the biologically active acidic form of leukoregulin, a 50,000-Da glycoprotein lymphokine with tumor growth inhibitory activity. Leukoregulin secreted by normal human lymphocytes was concentrated by 10,000 nominal molecular weight size exclusion ultrafiltration and by DEAE anion exchange chromatography using step elution with 0.02 M Tris-HCl: 0.1 M NaCl, pH 7.4. Preparative isoelectric focusing was carried out in a 110-ml vertical column containing 1% ampholines in a pH 4-6 gradient at 15 W constant power for 16-18 h, in a Rotofor 55-ml horizontal column containing 2% ampholines in a pH 4-6 gradient at 12 W constant power for 4-6 h, or in an immobiline pH 4.5-6.5 gradient within a 5% polyacrylamide 120 X 110 X 5-mm flat bed gel at 3 W constant power for 16-18 h. Recovery of biologically active leukoregulin from the vertical and horizontal ampholine columns was similar. The pH 4.9-5.2 fractions from the Rotofor ampholine column contained 4-7% and the fractions from the immobiline gel contained 4% of the leukoregulin activity applied to the electrofocusing column or gel, respectively. Analytical immobiline isoelectric focusing of the leukoregulin in the pH 4.9-5.2 fractions from the Rotofor column demonstrated that a single silver staining band with a pI of 5.1 can be obtained by this rapid method of preparative isoelectric focusing.     

Purification and characterization of an extracellular prolyl endopeptidase from Agaricus bisporus

Prolyl endopeptidase [EC 3.4.21.26] was purified to homogeneity from the culture filtrate of Agaricus bisporus by a procedure that comprised ammonium sulfate fractionation, anion-exchange chromatographies on DEAE-Toyopearl and DEAE-Sephadex, hydroxylapatite chromatography, and high-performance liquid chromatography (HPLC) on a TSKgel G 2000 SW column. The overall activity recovery was 8.6%. The enzyme was most active at or around pH 7.5 and was stable in the range of pH 5-9 when checked with Z-Gly-Pro-beta-naphthylamide as a substrate. The isoelectric point of the enzyme was about 4.8. The enzyme was a monomeric protein of molecular weight 78,000 +/- 2,000 as judged by gel permeation chromatography on Sephadex G-150 and electrophoresis on sodium dodecyl sulfate (SDS) polyacrylamide gel. The enzyme hydrolyzed Pro-X bonds and at least five subsites (S3, S2, S1, S1', and S2') were found to be involved in enzyme-substrate binding. Among them, S2, S1, and S1' subsites of the enzyme showed high stereospecificity. The enzyme was strongly inhibited by diisopropylfluorophosphate (DFP), Z-Gly-Pro-CH2Cl, Z-Pro-prolinal, Z-Pro-pyrrolidine, Z-Thiopro-pyrrolidine, Z-Pro-thiazolidine, Z-Thioprothiazolidine, and p-chloromercuribenzoate (PCMB), while it was not inhibited by phenyl-methylsulfonyl fluoride (PMSF), E-64, iodoacetamide, or metal chelators. Although the A. bisporus enzyme showed no immunological cross reaction with anti-bovine prolyl endopeptidase antiserum, the other characteristics were quite similar to those of mammalian and plant enzymes.