Should nagarse be used during the isolation of brain mitochondria?

When nagarse is used to isolate brain mitochondria, a proportion of the nagarse stays associated with the mitochondrial fraction. This results in no detrimental affect on the respiratory activities. The nagarse is active in the presence of 2.3% sodium dodecyl sulfate and when samples are prepared for sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the nagarse degrades a substantial amount of the mitochondrial proteins.     

Charge separation of proteins complexed with sodium dodecyl sulfate by acid gel electrophoresis in the presence of cetyltrimethylammonium bromide.

Globular proteins, casein, and membrane proteins which were reacted with sodium dodecyl sulfate were studied by acid urea gel electrophoresis. The sodium dodecyl sulfate bound tightly to the proteins, producing a more acidic charge which prevented migration into the gel. When cetyltrimethylammonium bromide was added to the sodium dodecyl sulfate-protein complexes, the sodium dodecyl sulfate apparently reacted with cetyltrimethylammonium bromide and dissociated so that the proteins migrated in acid gel in a normal manner as compared to the proteins without any added detergent. The sodium dodecyl sulfate-cetyltrimethylammonium bromide complex could be removed from the proteins by centrifugation. Thus, cetyltrimethylammonium bromide used in conjunction with acid gel electrophoresis allows direct comparison by charge of proteins fractionated in the presence of sodium dodecyl sulfate with the starting mixture of proteins not exposed to detergent. The reaction of cetyltrimethylammonium bromide with sodium dodecyl sulfate in acidic urea also provides a simple convenient method of removal of sodium dodecyl sulfate from proteins.     

Prenyltransferase from Saccharomyces cerevisiae. Purification to homogeneity and molecular properties.

Prenyltransferase (EC 2.5.1.1) has been purified to homogeneity from the supernatant fraction of yeast by ammonium sulfate fractionation, diethylaminoethyl-cellulose and hydroxylapatite chromatography, and column isoelectric focusing techniques. The active enzyme from isoelectric focusing columns emerged as a single symmetrical peak with specific activities 15- to 35-fold higher than previously reported preparations. The enzyme was found to be homogeneous by continuous polyacrylamide gel electrophoresis at pH 8.4 and discontinuous polyacrylamide gel electrophoresis at pH 6.9 as well as sodium dodecyl sulfate polyacrylamide electrophoresis at pH 7.0. By means of gel chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis, the protein was shown to be a dimer with a molecular weight of 84,000 plus or minus 10%. The isoelectric point of the enzyme was determined to be 5.3. The enzyme synthesizes farnesyl and geranylgeranyl pyrophosphates from dimethylallyl, geranyl, and farnesyl pyrophosphates. Michaelis constants for the enzyme were 4, 8, and 14 mu M for isopentenyl, dimethylallyl, and geranyl pyrophosphates, respectively.     

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.     

Characterization of the sex steroid binding protein of human pregnancy serum. Improvements in the purification procedure

The sex steroid binding protein (SBP) of human pregnancy serum was purified to homogeneity by the sequential use of ammonium sulfate precipitation, affinity chromatography on 5alpha-dihydrotestosterone-17beta-succinyldiaminoethyl-(1,4-butanediol diglycidyl ether)-agarose, and preparative polyacrylamide gel electrophoresis. The yield of pure SBP was improved from 5% as originally reported [Mickelson, K. E., and Petra, P. H. (1975), Biochemistry 14, 957] to 34%. Homogeneity of SBP was shown by equilibrium sedimentation ultracentrifugation in 6 M guanidine hydrochloride containing 0.1 M mercaptoethanol which yields a minimum molecular weight of 36 335 +/- 525. The protein is also homogeneous when examined by gel electrophoresis in the presence of sodium dodecyl sulfate. A value of 52 000 for the molecular weight is obtained by this method. SBP partially purified from Cohn fraction IV has also a molecular weight of 52 000 by gel electrophoresis in the presence of sodium dodecyl sulfate; that fraction is contaminated with another protein of molecular weight 90 000 which must be removed to obtain homogeneous SBP. The amino acid composition of SBP isolated from pregnancy serum is presented.     

Purification of rosmarinic acid synthase from cell cultures of Coleus blumei Benth

Rosmarinic acid synthase from cell cultures of Coleus blumei Benth. was purified to apparent homogeneity by fractionated ammonium sulfate precipitation (60–80% saturation), hydrophobic interaction chromatography, affinity chromatography and gel filtration. This purification procedure resulted in a 225-fold-enriched specific enzyme activity with a yield of 9%. The protein preparation was apparently pure according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis. The apparent molecular mass determined by gel filtration and SDS-PAGE was 77 kDa, indicating that rosmarinic acid synthase is a monomeric enzyme.Abbreviations DTT dithiothreitol - HIC hydrophobic interaction chromatography - RA rosmarinic acid - RAS rosmarinic acid synthase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis The financial support of the Deutsche Forschungsgemeinschaft is gratefully acknowledged. Two-dimensional gel electrophoresis was done with the help of Dr. Guy Bauw, University of Gent, Belgium.     

Purification and properties of acid phosphatase from cultured tobacco cells

One component of acid phosphatase was purified from cultured tobacco cells. The purified enzyme was homogeneous on polyacrylamide gel electrophoresis with or without sodium dodecyl sulfate. The enzyme possesses high activity toward nucleoside di- and triphosphate, much less activity toward nucleoside monophosphates and sugar esters. The MWs of the phosphatase determined by Sephadex G-100 gel filtration and dodecyl sulfate gel electrophoresis were 74000 and 76000, respectively. The phosphatase showed high affinity for concanavalin A-Sepharose and single superimposed bands of protein and carbohydrate on gel electrophoresis, suggesting that it is a glycoprotein.     

Identification of the milk fat globule membrane proteins: I. Isolation and partial characterization of glycoprotein B

The salt soluble proteins from the fat globule membrane of cow's milk were resolved into three fractions by Sephadex column chromatography in sodium dodecyl sulfate. One of the fractions, termed glycoprotein B, was purified by rechromatography to essentially one band on sodium dodecyl sulfate gel electrophoresis. It was found to contain 14% carbohydrate including sialic acid, mannose, galactose, glucose, glucosamine and galactosamine. The amino acid composition of glycoprotein B was determined; it has amino terminal serine and carboxyl terminal leucine. The molecular weight of this glycoprotein as estimated by sodium dodecyl sulfate gel electrophoresis is 49 500.     

Isolation of a 32P-labeled polypeptide of low molecular weight from phosphorylated human erythrocyte membranes.

The incorporation of 32P into well washed human erythrocyte membranes was studied in a medium containing [gamma-32P]ATP, Mg2+, and EGTA. Following phosphorylation, the membranes were completely solubilized in 1% sodium dodecyl sulfate and subjected to gel electrophoresis in dodecyl sulfate polyacrylamide. A large incorporation of radioactivity was observed in a band which migrated faster than component 7 (nomenclature of T. L. Steck, (1972), J. Mol. Biol. 66, 295) but slower than the bromophenol blue tracking dye, and did not stain with Coomassie Blue. Isolation of this band by preparative gel electrophoresis revealed that 41% of the radioactivity was associated with a 32P-labeled polypeptide. This polypeptide was further purified by gel chromatography on Sephadex LH-20 in chloroform-methanol-HCl, and Bio-Gel A 1.5m in dodecyl sulfate. Its amino acid composition is characterized by a high content of acidic residues. The calculated minimal molecular weight is 15084. Based upon the recovery of amino acids, the polypeptide fraction comprises at least 1.8% by weight of the total erythrocyte membrane proteins. An apparent molecular weight of 15000 was estimated by gel chromatography in dodecyl sulfate, while a range of 14000-16000 was estimated by electrophoresis in dodecyl sulfate polyacrylamide. The state of phosphorylation of this peptide may reflect a physiological function in the intact red cell.     

Purification and molecular characterization of rat intestinal brush border membrane dipeptidyl aminopeptidase IV

Dipeptidyl aminopeptidase IV (EC 3.4.14.-) was solubilized from a particulate membrane fraction of rat intestinal mucosa with Triton X-100. The solubilized enzyme was purified to homogeneity following ammonium sulfate fractionation, chromatography on DEAE-Sepharose and hydroxyapatite, gel filtration and preparative polyacrylamide gel electrophoresis. The final enzyme preparation had a specific activity of 55 units/mg protein representing a 1373 fold purification over the starting material. Purity was judged by polyacrylamide gel electrophoresis and double immunodiffusion. The molecular weight of the native undenatured enzyme was estimated to be 230000 by gel filtration and polyacrylamide gel electrophoresis. Electrophoresis under denaturing conditions (sodium dodecyl sulfate) indicated that the protein consists of two identical 98 kDa subunits. Dipeptidyl aminopeptidase IV is a glycoprotein containing approx. 8% carbohydrate by weight. A detailed analysis of the individual sugar components demonstrated that fucose, galactose, glucose, mannose, sialic acid and hexosamine sugars were present. The nature of the constituent asparagine linked oligosaccharide side chains was further examined following cleavage from the peptide backbone by hydrazinolysis. Following high voltage paper electrophoresis approx. 80% of the isolated oligosaccharide was found with the neutral fraction while the remaining 20% consisted of a single acidic component. Gel filtration of the neutral oligosaccharide fraction indicated that it contains approx. 19 sugar residues.     

Purification and properties of a thiol protease from rat liver nuclei

A thiol protease was purified about 800-fold from the chromatin fraction of rat liver by employing Sepharose 6B gel filtration, chromatofocusing and Sephadex G-100 gel filtration. It was nearly homogeneous on sodium dodecyl sulfate/polyacrylamide gel electrophoresis and its molecular weight was about 29000. The isoelectric point of the enzyme was 7.1. The pH optimum for degradation of 3H-labelled ribosomal proteins was 4.5. It is noticeable that the maximal activity was shifted to pH 5.5 by DNA, and that 30-40% of the maximal activity was observed at neutral pH in the presence of DNA. The activity was increased about twice by 2-4 mM dithiothreitol. The protease may be specific for the nuclei because it is different from all lysosomal thiol proteases ever known.     

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.     

Induction of rat hepatic alkaline phosphatase and its appearance in serum: electrophoretic characterization of liver-membranous and serum-soluble forms

Simultaneous bile duct ligation and colchicine injection (2 mg/kg body weight) in rats caused a remarkable induction of alkaline phosphatase in the liver. Concomitantly, a marked elevation of the enzyme activity occurred in the serum, and three activity peaks (peaks I, II, and III) were separated by Sephadex G-200 gel filtration. By several criteria for alkaline phosphatase isoenzymes it was determined that the liver-derived enzyme was distributed in peak I (30% of total serum activity) as a vesicle-bound form and in peak II (65%) as a soluble form, while the intestinal enzyme was contained in peak III (5%). The serum alkaline phosphatase in peaks I and II was compared with the liver enzyme extracted from plasma membrane with n-butanol. Under non-reducing conditions, the soluble form of peak II showed an electrophoretic mobility different from that of the liver enzyme; in the presence of sodium dodecyl sulfate the serum-soluble form migrated a little more slowly than the liver one, while in the presence of Triton X-100 the former migrated much faster than the latter. The sedimentable fraction of peak I was found to contain two forms corresponding to the serum-soluble and liver-membranous forms. Neuraminidase treatment of these two forms reduced their mobilities but did not abolish the relative difference in their mobilities on gel electrophoresis in the presence of either Triton X-100 or sodium dodecyl sulfate. Under reducing conditions, however, each form (which was dissociated into single subunits) migrated with an identical mobility on sodium dodecyl sulfate gel electrophoresis. These results suggest that the hepatic alkaline phosphatase exists as conformationally different forms in the serum and the liver membrane (even solubilized), but the difference is no longer preserved after their denaturation into subunits.     

Isolation and characteristics of endonuclease tightly bound to alpha-polymerase from the rat liver

Three major polypeptides are found in purified DNA polymerase alpha from rat liver: 160, 77 and 58 kDa. The electrophoretic analysis has identified polypeptide 160 kDa as the catalytically active subunit of DNA polymerase alpha. The other two polypeptides showed no DNA polymerase activity. Individual polypeptide p77 kDa purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis was used to produce antibodies in rabbits. Immunoblot analysis indicated that the complex DNA polymerase alpha-3'-5'-exonuclease contained polypeptide p77 kDa. To elucidate the function of the p77 kDa protein we have prepared an immunoabsorbent column with antibodies against the p77 kDa polypeptide. The antibody column purified p77 kDa protein was homogeneous according to sodium dodecyl sulfate gel electrophoresis. The activity of alpha-polymerase was increased approximately 10-fold as a result of purification of DNA polymerase alpha from the p77 kDa protein. The in vitro experiments showed the identity of the p77 kDa polypeptide to endonuclease. It cleaved both single-stranded and double-stranded DNA. The function of endonuclease p77 kDA in complex with DNA polymerase alpha remains obscure.     

Barley aleurone layers secrete a nuclease in response to gibberellic Acid : purification and partial characterization of the associated ribonuclease, deoxyribonuclease, and 3'-nucleotidase activities

Incubation of barley (Hordeum vulgare L. cv Himalaya) half-seeds with gibberellic acid enhances the secretion of ribonuclease and deoxyribonuclease from aleurone tissue (MJ Chrispeels, JE Varner 1967 Plant Physiol 42: 398-406; L Taiz, JE Starks 1977 Plant Physiol 60: 182-189). These activities were over 50-fold greater in medium of half-seeds incubated with gibberellic acid than in control medium. Ribonuclease and deoxyribonuclease activities initially appeared in the medium 24 to 48 hours after hormone induction and increased for up to 96 hours. Both activities had a pH optimum of 6.0 and a temperature optimum of 55°C. When the medium from gibberellic acid-treated half-seeds was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, the major ribonuclease and deoxyribonuclease activity bands comigrated. The two enzyme activities remained associated throughout a 2,700-fold purification employing ammonium sulfate fractionation, Heparin-Agarose affinity chromatography, and Reactive Blue 2-Agarose affinity chromatography. Also accompanying the ribonuclease and deoxyribonuclease activities throughout purification was the ability to hydrolyze the 3′-phosphoester linkage of 3′-AMP. The purified protein was composed of a single polypeptide with an apparent molecular weight of 36 kilodaltons as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It is concluded that in response to gibberellic acid, barley aleurone tissue secretes a nuclease having ribonuclease, deoxyribonuclease, and 3′-nucleotidase activities.     

Sodium- and potassium-activated adenosine triphosphatase of the nasal salt gland of the duck (Anas platyrhynchos). Purification, characterization, and NH2-terminal amino acid sequence of the phosphorylating polypeptide.

Sodium- and potassium-activated adenosine triphosphatase (NaK-ATPase) was purified from nasal salt glands of the duck (Anas platyrhynchos). Enzyme of specific activity 2,000 to 2,300 mumol of Pi/mg/hour was routinely obtained by sodium dodecyl sulfate treatment of a microsomal fraction of gland homogenate in the presence of 3 mM ATP followed by pelleting of the enzyme through a sucrose density gradient. Purified NaK-ATPase was stable for over 3 months at -20 degree. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography purified NaK-ATPase was shown to contain two polypeptide chains of molecular weight 94,000 and 60,000, the smaller of which was a glycoprotein. Purified enzyme of activity 2,300 mumol of Pi/mg/hour bound 3,600 pmol of ouabain/mg of enzyme protein. Reaction with [gamma-32P]ATP in the presence of Mg2+ and Na+ gave 7,025 pmol of acyl phosphate/mg of enzyme protein. The turnover number calculated from phosphorylation data was 5,460 min-1. Amino acid analysis of the polypeptide components of duck salt gland enzyme after separation by gel filtration chromatography in sodium dodecyl sulfate demonstrated strong compositional homology with highly purified NaK-ATPase preparations from other organs and species. The NH2-terminal amino acid of the 94,000-dalton component was glycine and of the 60,000-dalton component, alanine. With a combination of manual sequencing and automated Edman degradation, the NH2-terminal amino acid sequence of the 94,00-dalton catalytic subunit was found to be Gly-Arg-Asn-Lys-Tyr-Glu-Thr-Thr-Ala-()-Ser-Glu.     

Isolation and characterization of bovine factor VII.

Factor VII (proconvertin) has been purified approximately 5 x 10(5)-fold from bovine plasma with an overall yield of 30%. The isolation procedure involves barium sulfate adsorption and elution, DEAE-Sephadex batchwise adsorption and elution, benzamidine-agarose column chromatography, heparin-agarose column chromatography, and preparative polyacrylamide gel disc electrophoresis. The final product was homogeneous when examined by gel electrophoresis in the presence of sodium dodecyl sulfate. A minimal molecular weight of 45,500 was determined by sedimentation equilibrium. The molecular weight estimated by sodium dodecyl sulfate gel electrophoresis was 54,000. Factor VII is composed of a single polypeptide chain possessing an amino-terminal sequence of Ala-Asn-Gly-Phe-Leu-. The amino acid and carbohydrate compositions of factor VII are also reported.     

Purification and characterization of alpha-toxin of Clostridium oedematiens type A

The alpha-toxin of Clostridium oedematiens type A was purified from culture filtrate by two steps of column chromatography and repeated gel filtration. The purified alpha-toxin proved homogeneous in polyacrylamide gel electrophoresis and agar gel double diffusion. The molecular weight of the alpha-toxin was estimated at 280,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and at 260,000 by gel filtration on a Sephadex G-200 column. The isoelectric point determined by isoelectric focusing polyacrylamide gel electrophoresis was 6.1. No dissociation of the purified alpha-toxin into subunits was demonstrated in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 50% lethal and edematizing doses per mg protein of the purified alpha-toxin were 5.9 X 10(4) and 5.9 X 10(5), respectively. The L +/50 doses per mg protein of the toxin was 4.6 X 10(3). The purified alpha-toxin, when injected intradermally into the rabbit skin, induced increased vascular permeability. The toxin contained little or no hemolytic or lecithinase activity. These results attest that the lethal, edematizing and vascular permeability-enhancing activities elicited by C. oedematiens type A culture reside on the same protein molecule.     

Purification and characterization of a DNA polymerase from the archaebacterium Thermoplasma acidophilum

A thermophilic DNA polymerase has been purified to near homogeneity from the archaebacterium Thermoplasma acidophilum. Analysis of the purified enzyme by sodium dodecyl sulfate gel electrophoresis revealed a single polypeptide of 88 kDa which co-sediments with the DNA polymerase activity on sucrose gradients. Combination of sedimentation and gel filtration analyses indicates that this DNA polymerase is an 88-kDa monomeric enzyme in its native form. The DNA polymerase is resistant to aphidicolin, slightly sensitive to 2',3'-dideoxyribosylthymine triphosphate and inhibited by N-ethylmaleimide when preincubation with this reagent is performed at 65 degrees C. We find that a 3'----5' exonuclease activity is associated with the purified DNA polymerase; the two activities of the enzyme are optimal at 65 degrees C but the exonuclease activity is active in a broader range of lower temperatures and is more thermostable than the DNA polymerase activity.