Isolation of the mRNA encoding rat liver catechol-O-methyltransferase

A highly specific, well characterized rabbit antiserum to purified rat liver catechol-O-methyltransferase (COMT; EC 2.1.1.6) and the procedure of polysome immunoadsorption have been used to isolate a messenger RNA which encodes a single polypeptide when translated in vitro. Western blotting and immune fixation have shown multiple active forms of the enzyme to exist; a major, soluble one with MW of 23,000 and pI of 5.2 and another, membrane-bound one with MW of 26,000 and a pI of 6.2 (1). When translated in vitro, the purified message synthesizes a protein of molecular weight (MW) 23,000 and pI 5.2, values in agreement with those for purified enzyme reported by other investigators (2,3). Only the soluble form is seen after in vitro translation; the other immunoreactive proteins possibly arise due to post-translational modifications which do not occur in the lysate; or perhaps another mRNA exists. Cloning of the COMT cDNA will resolve this issue and should be feasible in light of our data indicating that the mRNA isolated here represents 0.46% of total rat liver polyadenylated message.     

Purification of a new extracellular 90-kDa serine proteinase with isoelectric point of 3.9 from Bacillus subtilis (natto) and elucidation of its distinct mode of action.

A new extracellular 90-kDa serine proteinase with an isoelectric point (pI) of 3.9 was purified from Bicillus subtilis (natto). Microheterogeneity was detected in the 50-kDa protease of bacillopeptidase F with pI 4.4 reported previously by Wu et al. and the sequence for the first 25 amino acids in the internal region of the enzyme was analyzed: ATDGVEWNVDQIDAPKAWALGYDGA. The cleavage sites in the oxidized B-chain of insulin by the proteinase were CySO3H7-Gly8, Val12-Glu13, Try16-Leu17, and Phe25-Tyr26. The activity was inhibited by phenylmethylsulfonyl fluoride (PMSF) and chymostatin, while the activity was not inhibited by proteinaceous Streptomyces subtilisin inhibitor (SSI) or alpha 2-macroglubulin.     

Characterization of the multiple forms and main component of dextransucrase from Leuconostoc mesenteroides NRRL B-512F

Multiple forms of dextransucrase (sucrose:1.6-alpha-D-glucan 6-alpha-D-glucosyltransferae EC 2.4.1.5) from Leuconostoc mesenteroides NRRL B-512F strain were shown by gel filtraton and electrophoretic analyses. Two components of enzyme, having different affinities for dextran gel, were separated by a column of Sephadex G-100. The major component voided from the Sephadex column was treated with dextranase and purified to an electrophoretically homogeneous state. The ]urified enzyme had a molecular weight of 64 000-65 000, pI value of 4.1, and 17% of carbohydrate in a molecule. EDTA showed a characteristic inhibition on the enzyme while stimulative effects were observed by the addition of exogenous dextran to the incubation mixture. The enzyme activity was stimulated by various dextrans and its Km value was decreased with increasing concentration of dextran. The purified enzyme showed no affinity for a Sephadex G-100 gel, and readily aggregated after the preservation at 4 degrees C in a concentrated solution.     

Bacillopeptidase F of Bacillus subtilis: purification of the protein and cloning of the gene.

We have purified a minor extracellular serine protease from Bacillus subtilis. Characterization of this enzyme indicated that it was most likely the previously reported enzyme bacillopeptidase F. The amino-terminal sequence of the purified protein was determined, and a "guess-mer" oligonucleotide hybridization probe was constructed on the basis of that sequence. This probe was used to identify and clone the structural gene (bpr) for bacillopeptidase F. The deduced amino acid sequence for the mature protein (496 amino acids) was preceded by a putative signal sequence of 30 residues and a putative propeptide region of 164 amino acids. The bpr gene mapped near pyrD on the chromosome and was not required for growth or sporulation.     

Isolation of Two Acetyl Esterases from Extracts of Bacillus subtilis

Acrylamide gel electrophoresis of crude cellular extracts of Bacillus subtilis revealed the presence of two acetyl esterases. Esterase A, the slower migrating enzyme, was found to be present in both vegetative and sporulating cells, whereas esterase B activity was more abundant after exponential growth ceased. Both esterases were present in the supernatant fraction of lysed spheroplasts and in a disrupted spore preparation. Of four pleiotropic asporogenous mutants tested, three exhibited decreased esterase B activity. Esterases A and B were partially purified by differential precipitation and co-chromatographed on diethylaminoethyl (DEAE)-cellulose (pH 7.5) and DEAE-Sephadex (pH 8.5). By employing gel filtration chromatography, the two esterases were separated, and molecular weights of 160,000 and 51,000 were estimated for esterases A and B, respectively. Esterase A was further purified to electrophoretic homogeneity by differential heating and preparative starch block electrophoresis. Sodium dodecyl sulfate-acrylamide gel electrophoresis of purified esterase A yielded a single protein band with a molecular weight of 31,000. The pI values of esterases A and B were determined to be 6.4 and 5.4, respectively.     

Purification and characterization of rat plasma kallikrein

Kallikrein enzyme initially was isolated from rat plasma by passage of citrated plasma through a DEAE-Sephadex column at pH 7.2. The active fraction was purified to electrophoretic apparent homogeneity by precipitation to 60% ammonium sulfate saturation, sequential passage through DE-52 cellulose, Sephadex G-200 and SP-Sephadex columns and finally by chromatofocusing on a PBE-94 column. The kallikrein content of each fraction during purification was monitored on the synthetic substrate N-alpha-tosyl-L-arginine methyl ester (TAME) and by its ability to form kinin from heat-treated rat plasma. The molecular weight was estimated by gel filtration to be 50,000 and by SDS-gel electrophoresis 41,000. Multiple isozymic forms were obtained with pI values ranging from 4.2 to 5.0. The enzyme has a pH optimum of 8.3. The Km and Vmax values for TAME, Bz-pro-phe-arg-pNA and H-D-val-leu-lys-pNA were 1.6, 0.16 and 1.7 mM and 3.09, 0.96 and 0.25 microM/mg/min respectively. The enzyme was inhibited by soybean trypsin inhibitor but not by lima bean trypsin inhibitor.     

Purification and characterization of arginase from Neurospora crassa

We have purified an enzymatically active form of arginase from a wild-type strain of Neurospora crassa to homogeneity. The enzyme has a subunit molecular weight of 38,300 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native protein migrated as a hexamer during gel-filtration chromatography with an apparent molecular weight of 266,000. The enzyme exhibited hyperbolic kinetics at pH 9.5 with an apparent Km for arginine of 131 mM. Antiserum was prepared against the purified enzyme and used to demonstrate the existence of three cross-reactive proteins in crude extracts of wild-type N. crassa. One of these proteins corresponded to the purified protein, whereas the other two were of molecular weights 41,700 and 26,800, respectively. Using the same antiserum, we found that rat liver, but not rat kidney, contains immunoreactive material. We also detected two proteins in extracts of Saccharomyces cerevisiae that were weakly cross-reactive with the antiserum. These data provide evidence for the existence of multiple forms of arginase in fungi as well as in mammals.     

Purification and characterization of the naturally occurring allelic variants of sn-glycerol-3-phosphate dehydrogenase in Drosophila melanogaster

The naturally occurring electrophoretic variants of sn-glycerol-3-phosphate dehydrogenase and a heterodimeric form of the enzyme resulting from a genetic cross of two variant strains of Drosophila were purified to homogeneity by a combination of DEAE-cellulose chromatography and 8-(6-aminohexyl)-amino-ATP-Sepharose affinity chromatography. Each purified protein was compared with respect to a number of physicochemical and kinetic properties. All forms of the enzyme were found to be similar, except for pI differences associated with the electrophoretic variation observed.     

Plasma alpha-galactosidase A:properties and comparisons with tissue alpha-galactosidases.

The human plasma form of alpha-galactosidase A (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) was highly purified and exhibited apparent Km values of 1.9 mM with 4-methylumbelliferyl-alpha-D-galactopyranoside and 0.23 mM with globotriglycosylceramide. Its inhibition with myo-inositol (Ki = 0.29 M) was similar to that observed with alpha-galactosidase A from various tissues. The plasma form of this lysosomal enzyme has a lower molecular weight of 96 600, a lower pI of 3.7 and faster electrophoretic mobility in polyacrylamide gels than the enzyme obtained from human liver. These data and the increased pI obtained after neuraminidase treatment suggest that the plasma form is an isoenzyme with a more highly sialylated carbohydrate moiety than the tissue isoenzymes.     

Isolation and properties of multiple forms of histidine decarboxylase from rat gastric mucosa.

The heterogeneity of histidine decarboxylase from rat gastric mucosa was studied. The partially purified enzyme was fractionated by preparative isoelectric focusing on a flat-gel bed by using narrow pH-range carrier ampholytes and a short focusing time. The activity was resolved, with about 95% recovery, into three forms, designated I, II and III, with pI values of 5.90, 5.60 and 5.35 respectively. These three forms exhibited similar molecular weights, indicating that the forms were not the result of different degrees of polymerization. By preparative refocusing each form refocused as a single peak of enzyme activity with reproducible pI, but a high loss of activity occurred with repeated focusing. Forms I, II and III were purified by the combined use of preparative isoelectric focusing and gel chromatography and other fractionation methods. The active forms could be distinguished by electrophoresis and isoelectric focusing on polyacrylamide gels and displayed protein heterogeneity. These forms were found in the crude extract and in the partially purified preparations in the presence or absence of proteinase inhibitors. Form II had the highest specific activity, but all three forms had the same optimum pH and Km value for histidine.     

Biochemical and immunological studies of purified mouse beta-galactosidase.

Beta-Galactosidase (EC 3.2.1.23) has been purified from the livers of C57BL/6J mice. The enzyme migrated as a single band of protein on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The molecular weight of the denatured and reduced enzyme was 63,000. The native form of beta-galactosidase appeared to be a tetramer of 240,000 at pH 5.0, which was reversibly dissociated at alkaline pH to a dimer with apparent molecular weight of 113,000. Multiple charge isomers of beta-galactosidase were resolved by polyacrylamide gel electrophoresis and ion exchange chromatography. Treatment of beta-galactosidase with neuraminidase markedly reduced its electrophoretic mobility. Purified enzyme as well as crude liver extract hydrolyzed p-nitrophenyl-beta-D-fucoside at one-tenth the rate of hydrolysis of the beta-galactoside. Antiserum to the purified enzyme precipitated the major portion of beta-galactosidase activity of mouse liver, brain, and kidney. This antiserum cross-reacts with beta-galactosidases from rat and Chinese hamster, but not with human, porcine, or bovine beta-galactosidase.     

Human alpha-L-iduronidase. I. Purification and properties of the high uptake (higher molecular weight) and the low uptake (processed) forms

Two major forms of human alpha-L-iduronidase have been individually purified over 175,000-fold to apparent homogeneity by sequential anion exchange, lectin affinity, and gel filtration chromatography. The two forms, initially designated as soluble and membrane-associated, were extracted from human lung in approximately equal amounts. Optimal solubilization of the membrane-associated form was facilitated by use of a non-ionic detergent or mannose 6-phosphate and saponin. Following detergent homogenization, the two forms were separated by anion exchange chromatography and then individually purified. The more electronegative form was membrane-associated, had a pI of approximately 5.9, and was selectively taken up (high uptake) by cultured Hurler syndrome fibroblasts; the more electropositive soluble form had a pI of about 6.6 and was incorporated into Hurler fibroblasts at a markedly lower rate (low uptake). After treatment with alkaline phosphatase, the pI values of both enzymes were about 7.8. Using 4-methylumbelliferyl-alpha-L-iduronide as substrate, the low and high uptake forms were each purified in milligram quantities to specific activities of 284,000 and 202,000 units/mg, respectively, with a combined yield greater than 35%. Each purified enzyme form migrated as a single protein band which also stained for enzymatic activity when electrophoresed in 7% native polyacrylamide disc gels at pH 4.3. By gel filtration, the high uptake form had an Mr = 85,000 whereas the Mr for the low uptake form was 68,000. Molecular weight estimates by analytical polyacrylamide gel electrophoresis were 82,000 and 70,000 for the high and low uptake forms, respectively. Rabbit anti-human low uptake alpha-L-iduronidase antibodies cross-reacted with the high uptake form as demonstrated by both immunotitration and Ouchterlony double immunodiffusion. Amino acid analysis revealed that the high uptake (higher molecular weight) form contained more arginine, glycine, alanine, glutamate or glutamine, leucine, isoleucine, histidine, and proline residues per molecule than the low uptake (lower molecular weight) form. Automated Edman degradation determined that the NH2-terminal residues of both forms were blocked. Both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high performance liquid chromatography demonstrated that each purified form was composed of several components; each post-high performance liquid chromatographic component retained catalytic activity and was immunologically cross-reactive with antibodies against the low uptake form.(ABSTRACT TRUNCATED AT 400 WORDS)     

Purification and Characterization of the (alpha)-Glucuronidase from Thermoanaerobacterium sp. Strain JW/SL-YS485, an Important Enzyme for the Utilization of Substituted Xylans

A cell-associated (alpha)-glucuronidase was purified to gel electrophoretic homogeneity from the thermophilic anaerobic bacterium Thermoanaerobacterium sp. strain JW/SL-YS485. This enzyme had a pI of 4.65, a molecular weight of 130,000, and two subunits; the molecular weight of each subunit was 74,000. The enzyme exhibited the highest level of activity at pH 5.4 and 60(deg)C, as determined by a 5-min assay. The K(infm) and k(infcat) values of the enzyme for 4-methylglucuronosyl xylobiose were 0.76 mM and 1,083 IU/(mu)mol, respectively. The Arrhenius energy was 26.4 kJ/mol. The specific activities of the enzyme with 4-O-methylglucuronosyl xylobiose, 4-O-methylglucuronosyl xylotriose, and 4-O-methylglucuronosyl xylotetraose were 8.4, 4.8, and 3.9 IU/mg, respectively. The purified (alpha)-glucuronidase and a (beta)-xylosidase purified from the same organism interacted synergistically to hydrolyze 4-methylglucuronosyl xylotetraose.     

Comparison of the Soluble and Membrane-Bound Forms of the Puromycin-Sensitive Enkephalin-Degrading Aminopeptidases from Rat

Enkephalin degradation in brain has been shown to be catalyzed, in part, by a membrane-bound puromycin-sensitive aminopeptidase. A cytosolic puromycin-sensitive aminopeptidase with similar properties also has been described. The relationship between the soluble and membrane forms of the rat brain enzyme is investigated here. Both of these aminopeptidase forms were purified from rat brain and an antiserum was generated to the soluble enzyme. Each of the aminopeptidases is composed of a single polypeptide of molecular mass 100 kilodaltons as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography. The antisoluble aminopeptidase antiserum reacts with both enzyme forms on immunoblots and inhibits both with nearly identical inhibition curves. The isoelectric points (pI = 5.0) of both forms were shown to be identical. N-terminal sequencing yielded a common sequence (P-E-K-R-P-F-E-R-L-P-T-E-V-S-P-I-N-Y) for both enzyme forms, and peptide mapping yielded 26 peptides that also appeared identical between the two enzyme forms. Studies on the nature of the association of the membrane enzyme form with the cell membrane suggest that this enzyme form does not represent the soluble form trapped during the enzyme preparation. It is suggested that the membrane form of the puromycin-sensitive aminopeptidase is identical to the soluble enzyme and that it associates with the membrane by interactions with other integral membrane proteins.     

粗毛栓菌胞外锰过氧化物酶的纯化及性质

培养于麦草粉上的白腐担子菌粗毛栓菌分泌胞外木质纤维素降解酶(纤维素酶、木聚糖酶、漆酶、锰过氧化物酶和木质素过氧化物酶)。经过超滤、盐析、离子交换层析、凝胶过滤和活性聚丙烯酰胺凝胶电泳等步骤,获得了初步纯化的锰过氧化物酶组分。利用变性聚丙烯酰胺凝胶电泳和等电点聚焦技术所测定的锰过氧化物酶的相对分子质量和等电点分别为35.7 ku和pI 2.8。研究结果表明,所纯化的锰过氧化物酶在407nm处具有最大光吸收峰,该酶最适作用pH值和温度分别为pH 5.3和35℃。     

Purification and characterization of novel transglutaminase from Bacillus subtilis spores

Transglutaminase activity was detected in suspensions of purified spores prepared from lysozyme-treated sporulating cells of Bacillus subtilis AJ 1307. The enzyme was easily solubilized from the spores upon incubation at pH 10.5 at 37 degrees C. The transglutaminase activity was separated into two fractions upon purification by hydrophobic interaction chromatography (TG1 and TG2). Each enzyme was purified to electrophoretic homogeneity (about 1,000-fold). Both enzymes had the same molecular weight of 29,000 as estimated by SDS-PAGE, had the same N-terminal 30 amino acid sequence, and also showed the same optimal temperature (60 degrees C) and pH (8.2). The purified enzyme catalyzed formation of cross-linked epsilon-(gamma-glutamyl)lysine isopeptides, resulting in the gel-formation of protein solutions such as alphas-casein and BSA.     

The interrelation between high- and low-molecular-weight forms of GM1-beta-galactosidase purified from porcine spleen

1) Two forms of acid beta-galactosidase [EC 3.1.23] with different molecular weights catalyzing the hydrolysis of GM1-ganglioside and p-nitrophenyl-beta-D-galactoside were separated and purified from porcine spleen. 2) The apparent molecular weights were 400,000-600,000 and 70,000-74,000 for the high (termed Am form) and low (termed A1 form) molecular weight forms, respectively. 3) On examination by sodium dodecyl sulfate (SDS)/polyacrylamide gel electrophoresis, both forms of the enzyme had a common protein band of molecular weight 63,000, and the Am form showed three additional protein bands with molecular weights of 31,000, 21,000, and 20,000. 4) Both forms of the enzyme had similar catalytic functions with regard to pH-optimum, Km, substrate specificity and sensitivity to substrate analogues and other substances such as detergents, bovine serum albumin (BSA) and NaCl. 5) Both forms of the enzyme were fairly stable upon preincubation at 45 degrees C at acidic pH (pH 4.5), but lost their activities at neutral pH (pH 7.0). 6) The A1 form was a monomer at neutral pH (pH 7.0) and formed a dimer at acidic pH (pH 4.5). However, most of the Am form could not be converted to a dimeric form on gel filtration at acidic pH.     

Immunochemical study of subtilisins obtained from Bacillus subtilis A-50 and some of its mutants]

Physico-chemical parameters of subtilisins from the original Bacillus subtilis A-50 strain (proteolytic activity, electrophoretic mobility, molecular weight, reactions with specific inhibitors) were similar to those mentioned in the literature for the enzymes of other strains. Immunological experiment has shown, that Bacillus subtilis A-50 subtilisins with various electrophoretic mobility do not differ in their antigenic properties. Enzymes with high electrophoretic mobility from mutant strains were similar to I--III subtilisin fractions from Bac. subtilis A-50 in the antigenic characteristics. However, the antigenic heterogeneity was observed in I, II and III enzyme fractions of some mutant strains. Subtilisins studied appear to form the isoenzyme system.     

Alanyl aminopeptidase of bovine seminal vesicle secretion

Multiple forms of an aminopeptidase hydrolysing L-alanine- and various other amino acid-beta-naphthylamides in bovine seminal vesicle secretion were studied after fractionation on gel filtration, anion exchange chromatography and chromatofocusing. Two forms of the enzyme were found in all these fractionations: one with a high molecular weight was aggregated or particle-bound and the other had a molecular weight of about 237,000. The high-molecular-weight form dissociated with Triton X-100 via an intermediate into the basic enzyme form with concurrent change in the pI and anionic sites. The basic form of the enzyme differed from the high-molecular-weight forms in substrate preference, response to some modifiers, thermal stability and kinetic constants.     

Purification and characterization of S layer proteins from Clostridium difficile GAI 0714

The S layer of Clostridium difficile GAI0714 was shown to be composed of two proteins, of 32 kDa and 45 kDa, as determined by SDS-PAGE. The two proteins were extracted with 8 M-urea (pH 8.3) from a cell wall preparation and purified by DEAE-Sepharose CL-6B chromatography followed by HPLC gel filtration. When solubilized in 0.1 M-urea, both proteins appeared to exhibit dimeric forms, with respective molecular masses of about 61 kDa and 99 kDa, upon HPLC. Although the amino acid compositions of the two proteins differed from each other, both proteins had a high content of acidic amino acids, very low contents of histidine and methionine, and no cysteine. The 32 kDa protein exhibited multiple isoelectric forms (pI 3.7-3.9), whereas the 45 kDa protein had a single form (pI 3.3). Radioiodination and immunogold labelling revealed that both proteins were exposed evenly over the entire cell surface. Based on immunodiffusion analysis using monospecific antiserum raised to the individual proteins, there was no antigenic relationship between the two proteins. Furthermore, immunoblot analysis showed that the antigenicity of the 32 kDa protein appeared to be strain specific, whereas that of the 45 kDa protein appeared to be group specific.