Studies on Metabolic Pathway of NAD in Yeast

Electrophoretically homogeneous preparation of yeast 5′~nucleotidase, one of NAD metabolizing system, was obtained from yeast autolysate by ammonium sulfate fractionation, chromatography, gel filtration and zone electrophoresis. The preparation had strong NAD-splitting activity, namely nucleotide pyrophosphatase activity.

Throughout purification steps, the ratio of the two activities were kept constant and they could not be separated even by treatments with EDTA, urea, thioglycol and alkaline buffer. These seem to suggest that both activities of 5′-nucleotidase and nucleotide pyrophosphatase localize on a single protein.     

NAD-linked formate dehydrogenase from methanol-grown Pichia pastoris NRRL-Y-7556

An NAD-linked formate dehydrogenase (EC 1.2.1.2.) from methanol-grown Pichia pastoris NRRL Y-7556 has been purified. The purification procedure involved ammonium sulfate fractionation, hollow-fiber H1P10 filtration, ion-exchange chromatography, and gel filtration. Both dithiothreitol (10 mm) and glycerol (10%) were required for stability of the enzyme during purification. The final enzyme preparation was homogeneous as judged by polyacrylamide gel electrophoresis and by sedimentation pattern in an ultracentrifuge. The enzyme has a molecular weight of 94,000 and consists of two subunits of identical molecular weight. Formate dehydrogenase catalyzes specifically the oxidation of formate. No other compounds tested can replace NAD as the electron acceptor. The Michaelis constants were 0.14 mm for NAD and 16 mm for formate (pH 7.0, 25 °C). Optimum pH and temperature for formate dehydrogenase activity were around 6.5–7.5 and 20–25 °C, respectively. Amino acid composition of the enzyme was also studied. Antisera prepared against the purified enzyme from P. pastoris NRRL Y-7556 form precipitin bands with isofunctional enzymes from different strains of methanol-grown yeasts, but not bacteria, on immunodiffusion plates. Immunoglobulin fraction prepared against the enzyme from yeast strain Y-7556 inhibits the catalytic activity of the isofunctional enzymes from different strains of methanol-grown yeasts.     

An amylase from fresh fruiting bodies of the monkey head mushroom Hericium Erinaceum

An amylase with a molecular mass of 55 kDa and an N-terminal sequence exhibiting similarity to enzyme from Bacteroides thetaitaomicron was isolated from fruiting bodies of the monkey head mushroom Hericium erinaceum. The purification scheme included extraction with distilled water, ion exchange chromatography on DEAE-cellulose and SP-sepharose, and gel filtration by FPLC on Superdex 75. The amylase of H. erinaceum was adsorbed on DEAE-cellulose in 10 mM Tris-HCl buffer (pH 7.4) and eluted with 0.2 M NaCl in the same buffer. The enzyme was subsequently adsorbed on SP-Sepharose in 10 mM ammonium acetate buffer (pH 4.5) and eluted with 0.3 M NaCl in the same buffer. This fraction was subsequently subjected to gel filtration on Superdex 75. The first peak eluted had a molecular mass of 55 kDa in SDS-PAGE. The amylase of H. erinaceum exhibited a pH optimum of 4.6 and a temperature optimum of 40°C. The enzyme activity was enhanced by Mn²⁺ and Fe³⁺ ions, but inhibited by Hg²⁺ ions.     

A simple purification method for the preparation of solubilized chlorophyllase from Chlorella protothecoides

A simple and rapid purification procedure is described for the routine preparation of large quantities of purified chlorophyllase (chlorophyll chlorophyllido-hydrolase, EC 3.1.1.14) from Chlorella protothecoides. The enzyme with specific activity of 960 nmol chlorophyll a hydrolyzed (mg protein)^?1 min^?1 was prepared by treating the homogenate with n-butanol, ammonium sulfate fractionations and gel filtration through Sephadex G-200 and Sepharose CL-6B, with a yield of 53% of activity based on the butanol extract. The enzyme preparation showed apparent homogeneity as judged by polyacrylamide gel electrophoresis. The procedures take only 4 days and can be operated routinely without column repacking.     

A Simple Purification Method for Chloroperoxidase and Its Use in Organic Media

A simple two-step purification method for chloroperoxidase from Caldariomyces fumago has been developed. After filtration of the mycelium the enzyme was bound to a DEAE Sepharose fast flow column. The enzyme was eluted with a 20–200 mM phosphate buffer, pH=5.8. After gel filtration on a Superose 12 HPLC column pure enzyme was obtained. Instead of gel filtration it was also possible to purify the enzyme by concentration over a membrane filter, 10 K cutoff. Concentration to 8% of the original volume yielded an enzyme preparation with R_z=1.31^b in 77% yield. The enzyme was active in t-butyl alcohol/water mixtures up to 70% t-butyl alcohol. The sulfoxidation of thioanisole proceeded readily (conversion > 99%) and with high enantioselectivity (>99%) in t-butyl alochol/water mixtures.     

Cytochrome c oxidase biosynthesis and assembly in Candida utilis yeast cells. Subunit structure and molecular weight determination.

Cytochrome c oxidase was purified from mitochondria of Candida utilis yeast cells. The purification procedure involved the hypotonic incubation of mitochondria followed by washes with increasing concentrations of KCl. The membrane fragments derived from this procedure were subjected to ammonium sulfate fractionation in the presence of 2% cholate. The purified active enzyme contained 8.5–9.2 nmol heme a per mg protein and was free of other types of hemoproteins. Upon Sephadex G200 gel filtration in the presence of cholate, an apparent molecular weight of 200,000 was estimated. A single band was observed for the active enzyme upon DEAE-cellulose chromatography, sucrose density gradient centrifugation, and Sephadex G200 gel filtration.Electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate resolved the enzyme into six polypeptide bands with apparent molecular weights of 49,000, 32,000, 28,000, 20,000, 13,500, and 8,000, respectively. The six components were also resolved by gel filtration on Sephadex G200, equilibrated with 0.1% sodium dodecyl sulfate, giving apparent molecular weights of 46,000, 35,000, 23,000, 19,000, 12,500, and 7,800.     

Purification and properties of alpha-mannosidase from bakers' yeast.

The yeast alpha-mannosidase [EC 3.2.1.24] was purified 1160-fold from the crude extract of the autolysate. The purified preparation was practically free from alpha-glucosidase, beta-glucosidase, alpha-galactosidase, beta-galactosidase, beta-mannosidase, and beta-N-acetylhexosaminidase activities. After the separation of yeast mannan during the purification procedures the enzyme became unstable but could be stored at 5 degrees C for three weeks with 50% loss of activity. The purified enzyme hydrolyzed both aryl and alkyl mannosides, but hydrolysis of yeast mannan proceeded slowly. Yeast mannan and Zn2+ increased the enzyme catalyzed hydrolysis of p-nitrophenyl mannoside, whereas NaN3, monoiodoacetate and methyl alpha-D-mannoside acted as inhibitors. The molecular weight was estimated to be 450,000 by gel filtration.     

Purification and some kinetic properties of catalase from parsley (Petroselinum hortense Hoffm., Apiaceae) leaves

In this study, catalase (CAT: EC 1.11.1.6) was purified from parsley (Petroselinum hortense) leaves; analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps, including preparation of homogenate, ammonium sulfate fractionation, and fractionation by DEAE-Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 9.5% and had a specific activity of 1126 U (mg proteins)(-1). The overall purification was about 5.83-fold. A temperature of 4 degrees C was maintained during the purification process. Enzyme activity was spectrophotometrically measured at 240 nm. In order to control the purification of the enzyme, SDS-polyacrylamide gel electrophoresis was carried out in 4% and 10% acryl amide for stacking and running gel, respectively. SDS-polyacrylamide gel electrophoresis showed a single band for the enzyme. The molecular weight was found to be 183.29 kDa by Sephadex G-200 gel filtration chromatography. The stable pH, optimum pH, and ionic strength were determined for phosphate and Tris-HCl buffer systems. In addition, K(M) and V(max) values for H(2)O(2), at optimum pH and 25 degrees C, were determined by means of Lineweaver-Burk plots.     

Structural and chemical characterization of a homogeneous peptide N-glycosidase from almond

A peptide N-glycosidase that catalyzes the hydrolysis of N-linked oligosaccharide chains from glycopeptides and glycoproteins has been purified to homogeneity from almond emulsin and from almond meal. Purification from almond emulsin using ion-exchange chromatography, gel filtration chromatography, and preparative polyacrylamide gel electrophoresis gave an enzyme which was purified more than 700-fold and with a yield of 63%. An alternative procedure, more suitable for efficient large scale purification, used ion-exchange, affinity, and gel filtration chromatography. When purification began with almond emulsin, the enzyme was purified 1200-fold with a 37% yield, while when purification began with almond powder, the enzyme was purified 9000-fold with a yield of 45%. The homogeneous enzyme is stable at 4 degrees C for several months in 10 mM sodium acetate, pH 5.0, buffer. The peptide N-glycosidase is itself shown to be a glycoprotein consisting of a single polypeptide chain with a molecular weight of 66 800 on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Circular dichroism spectra of the native molecule indicate the presence of a high (approximately 80%) alpha-helix content. The amino acid and carbohydrate contents of the enzyme are presented. When a convenient new assay with a turkey ovomucoid glycopeptide as a substrate is used, the enzyme preparation exhibits a broad pH optimum centered between pH 4 and pH 6. The enzyme is readily inactivated by SDS and guanidine hydrochloride, but it is stable in the presence of moderate concentrations of several other protein denaturants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Purification of phosphoenolpyruvate carboxykinase from Saccharomyces cerevisiae and its use for bicarbonate assay

Electrophoretically homogeneous phosphoenolpyruvate carboxykinase (EC 4.1.1.49) from Saccharomyces cerevisiae was obtained in high yields by means of a two-step purification procedure consisting of ion-exchange chromatography and affinity chromatography on adenosine 5'-monophosphate-Sepharose 4B. In the latter step the binding of the enzyme to the resin specifically required the presence of Mn2+. The enzyme was eluted when Mn2+ was removed by addition of ethylenediaminetetraacetate to the elution buffer. Homogeneity, molecular weight, and subunit composition of phosphoenolpyruvate carboxykinase were checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration. A factor which caused an underestimation of the enzyme activity in crude extracts was identified as adenylate kinase. Finally, a method is proposed for the enzymatic assay of bicarbonate using a purified phosphoenolpyruvate carboxykinase preparation.     

Rapid procedure for the isolation of cytochrome c peroxidase

A simple, rapid method is described for the preparation of cytochrome c peroxidase from baker's yeast. The procedure involves lysis of the yeast in the presence of ethyl acetate, extraction of the peroxidase in 0.05 M sodium acetate buffer, pH 5.0, and the concentration of the crude extract on a DEAE-agarose column. The DEAE eluate is further concentrated by ultrafiltration, and gel filtration of the concentrate results in a highly purified form of the enzyme. Consistent yields with 80% recovery are easily obtained. Protein isolated by this method in the presence or absence of the protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), contains purely high-spin Fe(III) heme as monitored by its resonance Raman spectrum.     

Bakers' yeast protease a purification and enzymatic and molecular properties

It has been previously demonstrated in our laboratory that uridine nucleosidase (EC 3.2.2.3) is inactivated by yeast protease A (EC 3.4.23.8). A complete purification procedure for protease A from bakers' yeast, which lacks the acidic activation step used by other workers, and the major properties of the enzyme are shown. The enzyme is homogeneous as judged by disc gel electrophoresis. Its molecular weight, calculated from both sodium dodecyl sulfate-disc gel electrophoresis and gel filtration experiments, is around 45,000. The protein does not possess quaternary structure. The isoelectric point is 4.1. Carbohydrate content is around 8%. Amino acids analysis and sulfur analysis reveal the presence of 1-SH group and two disulfide bridges. The free-SH group does not seem to be involved in catalysis. Amino terminal analysis shows that isoleucine is at the amino terminal position. The pH optima are 2.4 for the hydrolysis of azocasein and casein, and 3.3 for the hydrolysis of hemoglobin. The K_m value for hemoglobin is 1.7 × 10^?5m. The inhibition exerted by pepstatin on the proteolytic activity of protease A is pH dependent. Among various yest enzyme substrates only uridine nucleosidase is inactivated by protease A.     

Human blood group glycosyltransferase. II. Purification of galactosyltransferase

A galactosyltransferase, which converts blood group O red bloodcells to B-cells, was purfied to homogeneity from plasma of blood group B subjects. The stepwise purification procedures include: (a) column chromatography with CM-Sephadex, followed by ammonium sulfate fractionation; (b) Sephadex G-200 gel filtration; (c) column chromatogr,phy with DEAE-Sephadex; and (d) column chromatography with hydroxylapatite. The procedures provided about a 400,000-fold increase of specific activity with a 40 to 50% yield. Further purification of the enzyme was performed by small scale preparative acrylamide gel electrophoresis at pH 4.3. The final enzyme preparation showed a single protein band which coincided with enzyme activity, in acrylamide gel electrophoresis, and revealed a single protein band in sodium dodecyl sulfate-gel electrophoresis. Judging from the molecular weight, which was estimated by Sephadex gel filtration, and subunit size estimated by sodium dodecyl sulfate-gel electrophoresis, the enzyme is presumably in a dimeric form. The enzyme required Mn2+ for its activity and had a pH optimum at 7.0 to 7.5.     

Purification of p-hydroxyphenylpyruvate hydroxylase from rat liver--requirement for cofactors.

The enzyme p-hydroxyphenylpyruvate hydroxylase (EC 1.13.11.27) from rat liver was studied with the assay method which measures the release of 14CO2 from p-hydroxyphenyl [carboxy-14C]pyruvate. Extensive dialysis of the crude enzyme extract against Tris buffer or purification involving ammonium sulfate, gel filtration, and ion exchange results in loss of enzyme activity that can be reactivated by Fe2+, dichlorophenolindophenol, and various other agents. The effect of these activators depends critically on their final concentration in the assay media. A 70-fold purification of the enzyme fraction yielded a preparation which behaved as a single protein band in Sephadex G-150. It had an isoelectric point at 5.85 and molecular weight of 63 000. The enzyme obtained appears to be different in some respects from those described by other workers from the liver of dog, human, chicken, and frog.     

Gamma-cystathionase: the non-ideal gel filtration high performance liquid chromatography. Physico-chemical and immunochemical characteristics of the enzyme

The rapid method for gamma-cystathionase purification was developed. It is based on the non-ideal gel filtration HPLC. The isolated homogeneous enzyme was used for immunization and immunosorbent preparation. A monospecific polyclonal antibody was prepared. The substrate specificity of the isolated enzyme was studied.     

Partial purification and characterization of glycylprolyl dipeptidyl aminopeptidase in porcine pancreas

This study reports the presence of glycylprolyl dipeptidyl aminopeptidase in porcine pancreas, and its partial purification and some properties. Crude enzyme preparation was obtained by extraction from acetone-dried powder of the pancreas at pH 7.6. For solubilization of enzyme, freezing and thawing were carried out. Crude enzyme extract was fractionated with ammonium sulfate precipitation, gel filtration on Sephadex G-200 column and ion-exchange chromatography on DEAE-cellulose. Partially purified enzyme showed 2897-folds purification. The enzyme activity on polyacrylamide gel electrophoresis showed good agreement with a main protein band stained with Coomassie brilliant blue. Molecular weight of this enzyme from the pancreas was estimated to be 300 000 by gel filtration on Sephacryl S-300 column. Optimum pH was between 8.5 and 9.0, and K_m value for glycylproline-p-nitroanilide tosilate was 0.33 mM. This enzyme from the pancreas was a serine enzyme and was relatively stable to heat at 60°C for 10 min.     

Marine bacterial proteases. I. Characterization of an endopeptidase produced by Vibrio B-30

A purification procedure is described for a highly active endopeptidase produced by a marine bacterium (Vibrio B-30). The purified enzyme was shown to be homogeneous by ion-exchange chromatography, gel filtration, and electrophoresis. A crystalline preparation was obtained. The pH optimum of the enzyme was about 7.0, and it was stable in the pH range of 5.0–8.5. Using hemoglobin as the substrate, a K_m of 0.095 mm was obtained. The temperature optimum of the enzyme was 40 ° in the absence of calcium and about 50 ° in the presence of 10⁻³ m calcium. Calcium both activated and stabilized the enzyme against thermal denaturation. The enzyme was shown to be a serine protease which was irreversibly inhibited by certain metal-complexing agents. Gel filtration studies revealed that Vibrio B-30 endopeptidase had a molecular weight of 49,000 ± 5,000 but it rapidly autolyzed during the second and third passage through a gel column. Removal of a metal ion (probably calcium) resulted in the formation of a high-molecular-weight, enzymatically inactive component and a low-molecular-weight, partially active component.     

Resolution of brewer's yeast pyruvate decarboxylase into multiple isoforms with similar subunit structure and activity using high-performance liquid chromatography.

A method for the purification of brewer's yeast pyruvate decarboxylase (EC 4.1.1.1) that resolves the enzyme into multiple active isoforms was developed. Seven activity fractions are resolved by DEAE HPLC chromatography. Among these fractions, three distinct subunit composition isoforms are apparent by sodium dodecyl sulfate-polyacrylamide gel electrophoresis: alpha 4, a homotetrameric holoenzyme consisting of the lower mass subunit; alpha 2 beta 2, a heterotetrameric holoenzyme consisting of lower and higher mass subunits; and beta 4, a homotetrameric holoenzyme consisting of the higher mass subunit. Beta 4 is a heretofore unreported form which may represent the unproteolyzed form of the enzyme. The Km and Vmax for the alpha 4 and beta 4 isoforms are identical within the limits of experimental error, as is their behavior vis-à-vis the allosteric regulator pyruvamide. All active isoforms exist as tetramers according to gel filtration analysis under native conditions. The purification has been successfully applied to pyruvate decarboxylase isolated from two different species of yeast and therefore is likely to be of general utility for purification of this enzyme from other yeast sources. Conditions under which all three isoforms demonstrate exceptional stability, making them amenable to prolonged physicochemical studies at 4 degrees C and even at room temperature are reported.     

Purification and properties of the allophanate hydrolase from Chlamydomonas reinhardii

Allophanate hydrolase was purified to homogeneity from extracts of Chlamydomonas reinhardii grown phototrophically using urea as sole source of nitrogen. The following sequence of steps comprised the purification procedure: (1) protamine sulfate precipitation; (2) ammonium sulfate fractionation; (3) poly(ethylene glycol) fractionation; (4) batch-wise DEAE-cellulose adsorption; (5) Sepharose 6-B gel filtration; (6) hydroxyapatite chromatography. This procedure yielded an allophanate hydrolase preparation which was homogenous as judged by polyacrylamide gel electrophoresis. The molecular weight, as determined by gradient polyacrylamide electrophoresis and gel filtration, was 110 000 and 100 000, respectively. The pH optimum of this enzyme was approximately 9.0, while the K_m for allophanate was 0.55 mM. Allophanate hydrolase was sensitive to N-ethylmaleimide but was protected from this inhibition by allophanate. Malonic acid, oxaloacetic acid, and acetoacetic acid were inhibitory to allophanate hydrolysis.     

Purification and preliminary characterization of human leukocyte elastasel.

Affinity chromatography permits the purification of 1–3 mg of human leukocyte elastase from the leukocytes contained in 500 ml of whole blood. Lysosomal granule proteins are extracted from polymorphonuclear leukocytes and subjected to chromatography on a column of elastin-Sepharose. Contaminating proteins are eluted with buffer containing 1 m NaCl and then elastase activity is eluted with buffer containing 8 m urea. The enzyme retains all of its esterase activity against N-t-BOC-l-alanine p-nitrophenyl ester after exposure to 8 m urea and retains 22% of its activity in the presence of 1% sodium dodecyl sulfate. In sodium dodecyl sulfate and 2-mercaptoethanol leukocyte elastase undergoes autolysis giving rise to several low molecular weight fragments. The molecular weight of the native enzyme is found to be 22.000 by both gel filtration and sodium dodecyl sulfate—acrylamide gel electrophoresis. A characteristic set of four isozymes is seen after acrylamide disc gel electrophoresis at pH 4.5. All bands are active against elastin and also contain carbohydrate by the periodic acid-Schiff stain. On the basis of stain intensity, the slower moving isozymes appear to be richest in carbohydrate. Active leukocyte elastase forms a complex with α₁-antitrypsin in a 1:1 molar ratio. The elastase must be enzymatically active for complex formation to occur.