Purification of bovine liver microsomal NADH-cytochrome b5 reductase using affinity chromatography

Microsomal NADH-cytochrome $\text{b}{}_5$ reductase has been purified from bovine liver by an improved procedure which employs affinity chromatography on ADP-agarose in combination with anion exchange chromatography. The reductase was extracted from a 105,000 × $\text{g}$ microsomal pellet with Triton X-100. The overall purification from isolated microsomes was 98-fold and the yield was 10%. The preparation was nearly homogeneous on SDS-PAGE. This procedure requires less time and effort than previously described procedures. Partially purified cytochrome $\text{b}{}_5$ is also obtained.     

Solubilization and partial purification of cytochrome P-450 from rat lung microsomes

Cytochrome P-450 from rat lung microsomes has been solubilized and purified 8-fold by using affinity chromatography on an ω-amino-$\text{n}$-octyl derivative of Sepharose 4B. The purified fraction was free of cytochrome $\text{b}$₅ and NADPH-cytochrome $\text{c}$ reductase and showed spectral characteristics similar to those of lung microsomal cytochrome P-450. When combined with NADPH-cytochrome $\text{c}$ reductase partially purified from liver microsomes, the cytochrome P-450 fraction supported the hydroxylation of benzo (α)pyrene and the activity was proportional to the content of the hemoprotein. No absolute requirement for phosphatidylcholine was found.     

Extraction of pure ribosomal protein and removal of Coomassie blue from acrylamide gels

A method has been developed to recover pure ribosomal proteins from two-dimensional polyacrylamide electrophoresis slabs. Proteins and Coomassie blue were extracted from the gels and separated by passing them through a Sephadex G-25 column. All the steps were performed in the presence of 66% ($\text{v}\text{v}$) acetic acid. The technique has been applied to Escherichia coll ribosomal proteins labeled with ¹²⁵I.     

Primary structure of heat-stable enterotoxin produced by Yersinia enterocolitica

A heat-stable enterotoxin was isolated and purified from the culture supernatant of $\text{Yersinia enterocolitica}$ by reversed-phase high-performance liquid chromatography. The amino acid sequence of the purified toxin was determined to be as follows: Gln-Ala-Cys(X)-Asp-Pro-Pro-Ser-Pro-Pro-Ala-Glu-Val-Ser-Ser-Asp-Trp-Asp-Cys-Cys-Asp-Val-Cys-Cys-Asn-Pro-Ala-Cys-Ala-Gly-Cys (X: not determined). The C-terminal sequence containing 6 half-cystine residues was highly homologous to that of heat-stable enterotoxin of enterotoxigenic $\text{Escherichia coli.}$     

Resolution of cyclic AMP stimulated protein kinase from polymerization-purified brain microtubules.

Polymerization-deploymerization purified microtubules from mouse brain contain, in addition to tubulin, several minor proteins, including protein kinase activity. The protein kinase copurifies with microtubules in constant proportion to tubulin through two, three, or four cycles of polymerization; it can be resolved from tubulin by gel filtration chromatography and has an apparent molecular weight of 280,000. Its activity is stimulated 7-fold by cyclic AMP, and resembles the soluble brain protein kinase described by Miyamoto $\text{et al.}$ (1). The microtubule preparation serves as an endogenous substrate for this protein kinase; both 6S and 30S tubulin are substrates for phosphorylation to the extent of about 0.10 ± 0.05 moles/mole.     

Partial purification of human liver cytochrome P 450.

Human liver cytochrome P 450 was partially purified by hydrophobic chromatography on Octyl-Sepharose, followed by ion-exchange chromatography on DEAE-cellulose. Two fractions (A and B) were obtained; cytochrome P 450 of fraction A was purified sixfold, with an overall yield of about 6 %. Its spectral properties were similar to those previously described in animal cytochromes P 450. Moreover, p-nitroanisole-O-demethylase activity could be obtained in a reconstituted system involving cytochrome P 450 of fraction A, human NADPH-cytochrome $\text{c}$ reductase and phospholipids.     

Purification of thiamine-binding protein from Escherichia coli

An affinity column coupled with thiamine pyrophosphate quantitatively absorbs the thiamine-binding activity from a partially purified preparation of $\text{Escherichia}\text{coli}$. The thiamine-binding protein can be eluted from the affinity column in high yield by use of 8 M urea-containing buffer. Approximately 90-fold purification occurs by affinity chromatography yielding a preparation which appears to be homogenous.     

Solubilization and partial purification of a rat intestinal 1,25-dihydroxyvitamin D3 binding protein.

A protein containing fraction that will bind 1,25-dihydroxyvitamin D₃ both $\text{in}$$\text{vivo}$ and $\text{in}$$\text{vitro}$ has been solubilized from the nuclear-debris fraction of rat intestinal mucosa and purified 15-fold.     

Affinity chromatography of thermolysin and of neutral proteases from B. subtilis

Affinity chromatographic systems are described for the purification of neutral metalloendopeptidases on columns of acetyl-$\text{D}$-phenylalanine or succinyl-$\text{D}$-leucine covalently linked to Sepharose by spacers of various lengths. The neutral proteases of $\text{B. subtilis}$ are separated in a single chromatographic procedure from all other proteins of the culture filtrates and subfractionated into two active species. An analogous chromatographic system is effective in the purification of thermolysin of $\text{B. thermoproteolyticus}$.     

Sugar specificity of anti-B hemagglutinin produced by Streptomyces sp

A hemagglutinin specific for blood group B antigen has been purified to 190-fold from the culture fluid of a strain of $\text{Streptomyces}$ sp. by conventional procedure involving ammonium sulfate fractionation and column chromatography. The molecular weight of the partially purified preparation was estimated to be approximately 5000±1000; this value is extremely small as compared with those of hemagglutinins which have been so far isolated from various sources.Hemagglutination-inhibition tests revealed that the $\text{Streptomyces}$ agglutinin has a specificity to combine with D-galactose and several saccharides having D-galactose residues at the non-reducing terminal, and that the special configuration of the hydroxyl groups at C-2 and C-4, particularly the hydroxyl group at C-2, is essential for binding of the sugars to the hemagglutinin.     

Galactosyltransferase: confirmation of equilibrium-ordered mechanism.

A thermostable protein that strongly inhibits the soluble $\text{E. coli}$ D-alanine carboxypeptidase was isolated from a cell-free extract of $\text{E. coli B}$. The inhibitor was purified 140-fold by heat treatment, selective precipitation at pH 4.5, ion exchange chromatography on DEAE-cellulose and gel chromatography on Sephadex G-100. Inhibition of soluble D-alanine carboxypeptidase by this inhibitor is reversed by cations such as Mg⁺⁺ or Na⁺ and abolished by digestion of the inhibitor with proteolytic enzymes. The inhibitor does not affect either the particulate D-alanine carboxypeptidase of $\text{E. coli}$ or the growth of the bacteria.     

Purification of a new glutathione S-transferase (transferase μ) from human liver having high activity with benzo(α)pyrene-4,5-oxide

A new glutathione $\text{S}$-transferase from human liver has been purified to homogeneity in good yield by use of ion-exchange chromatography on DEAE-cellulose, affinity chromatography on $\text{S}$-hexylglutathione coupled to epoxy-activated Sepharose 6B, and chromatography on hydroxyapatite. This new enzyme, transferase μ, is present in high concentration, but only in some individuals. It has an isoelectric point at about pH 6 to 6.5 and a different substrate specificity than the previously described alkaline transferases α-ε from human liver. Especially noteworthy is the finding of high activity against benzo(α)pyrene-4,5-oxide. Glutathione $\text{S}$-transferase μ has about 20-fold higher activity with this substrate than have the alkaline transferases. The most pronounced difference was found with $\text{trans}$-4-phenyl-3-buten-2-one which was >100-fold better as substrate for transferase μ than for the previously described transferases.     

Translation of bacteriophage T4 mRNA into active lysozyme by a wheat germ cell-free system.

T4 bacteriophage mRNA for lysozyme was extracted from T4 phage infected $\text{E. coli}$ cells, partially purified by column chromatography, and translated in a heterologous cell-free protein synthesizing system prepared from wheat germ. The translation product was confirmed by SDS polyacrylamide gel electrophoresis and enzymatic activity — bacteriolysis as tested with $\text{Micrococcus luteus}$. The specific activity of the enzyme prepared was 660 U/mg.     

Purification and properties of acid phosphatase from Drosophila virilis

One allelic form(Acph²) of acid phosphatase (EC 3.1.3.2) specified by Acph locus of Drosophila virilis was purified about 1000-fold in 20% yield. The purified preparation was fairly homogeneous as examined by disc and SDS-polyacrylamide gel electrophoresis. The enzyme protein is considered to be a dimer composed of identical or very similar subunits which have a molecular weight of 50,000. The enzyme is also a glycoprotein which contained 20% neutral sugars and a low content of hexosamines. The optimum pH of the enzyme activity was 5.0 and optimum temperature was 53°C. The Acph² enzyme was shown to be relatively heat stable. The purified preparations have a $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ for $\text{p-}\text{nitrophenyl}$ phosphate of 0.2 mM and a broad substrate specificity. The enzyme was inhibited by compounds which inhibit high-molecular weight-acid phosphatase in eukaryotes, localized to lysosomal fractions. The isoelectric point was 9.8. The amino acid analysis revealed a high content of glycine and alanine, but there was no characteristic feature of the composition which accounted for the high isoelectric point.     

Isolation and purification of myotube and myoblast nuclei from cultures of embryonic chick skeletal muscle.

Methods are described for the preparation of purified myotubes from embryonic chick skeletal muscle cultures and the preparation of purified nuclei from both myotubes and myoblasts. Myotubes are released from the culture dish by digestion of their collagen substratum with collagenase, and purified by sucrose density gradient sedimentation. Nuclei are prepared from the isolated myotubes by controlled homogenization in Ca²⁺-free medium and sedimentation through 2.1 M sucrose. Nuclei are prepared from cultured myoblasts in a similar fashion, with the inclusion of the non-ionic detergent NP-40 in the homogenization medium and sedimentation through 2.4 M sucrose. Phase contrast microscopic examination showed that the nuclear preparations are free of visible cytoplasmic contamination, and are morphologically similar to nuclei observed in situ. Biochemical assays (protein/DNA and $\text{RNA}\text{DNA}$ ratios) confirm the purity of the nuclear preparations. Both nuclear preparations have been used to prepare purified chromatin which has spectral and chemical properties similar to those reported for chromatin purified directly from several chick tissues.     

Formate : a new electron donor for nitrite reduction in Escherichia coli K12.

Reduction of nitrite by unbroken cells of $\text{Escherichia coli}$ occurs with formate as electron donor. This activity constitutes about 25 % of the overall nitrite reduction. Electron transfer is performed through the formate dehydrogenase and, probably, a cytochrome-containing chain.     

Purification of ferredoxin-NADP+ oxidoreductase from cyanobacteria by affinity chromatography on 2′,5′-ADP-Sepharose 4B

A simple and rapid method for the purification to homogeneity of ferredoxin-NADP⁺ oxidoreductase (EC 1.18.1.2) from the nitrogen-fixing filamentous cyanobacterium Anabaena sp. strain 7119 is described. A crude extract prepared by solubilizing the cells with a detergent was first partially purified on a DEAE-cellulose column and then chromatographed on 2′,5′-ADP-Sepharose 4B. Ligand-bound ferredoxin-NADP⁺ oxidoreductase was eluted by a linear gradient of NaCl. The overall procedure provided an enzyme purified about 400-fold with a yield of 60 to 70%. The final enzyme preparation exhibited a specific activity of 120 units/mg protein and an absorbance ratio $\text{A}{}_{280}\text{A}{}_{458}$ of 8.26. The enzyme protein migrated as a single band when subjected to polyacrylamide gel electrophoresis and chromatographed as a single isoelectric species under chromatofocusing.     

Evidence that Escherichia coli 30 S ribosomal subunit populations are conformationally heterogeneous.

We have estimated the number of sites on each protein of the 30 S ribosome which are accessible to chemical iodination. First, the total number of iodinatable sites was determined for the intact 30 S ribosome. The proteins were extracted, separated and the relative distribution of iodine in each protein determined. This distribution of iodine divided into the total sites per ribosome gave an estimate of the number of sites per individual protein.Second, the iodinated proteins were purified and their trypsin digestion products separated. The number of radioactive peptides was taken as a measure of the number of sites on that protein open to the iodination reaction. The number of iodinatable sites for each protein was found to be radically different by the two methods. In almost all cases, the number of unique, radioactively labeled peptides, derived from a given 30 S protein, far exceeded the total incorporation into that protein. We suggest that the best explanation for this unexpected discrepancy is that the 30 S ribosome population we used in these experiments is heterogeneous in its topography.In addition we have compared the topography by the chemical iodination procedure for ribosomes in two different conformations: active and inactive (see Zamir et al., 1971). We have found very little change in the chemical reactivity of the proteins when the ribosomes are in the two different conformations. The most notable changes involve proteins S10, $\text{S}\text{18}\text{S}\text{19}$ and especially $\text{S}\text{12}\text{S}\text{13}$.     

Intramolecular determination of primary kinetic isotope effects in hydroxylations catalyzed by cytochrome P-450

Isotope effects for hydroxylation reactions catalyzed by cytochrome P-450 have usually been measured by comparing the overall reaction velocities of deuterated and nondeuterated substrates. Since the rate-limiting step is probably not the single reaction involving covalent bond cleavage, such an approach does not yield information about the primary isotope effect. We measured the primary kinetic isotope effect for benzylic hydroxylation by a method utilizing intramolecular competition, using the symmetrical substrate 1,3-diphenylpropane-1,1-d₂. These experiments yield a value of $\text{k}{}_{\mathrm{<mtext>H</mtext>}}\text{k}{}_{\mathrm{D}}\text{= 11}$, a larger effect than has previously been reported for benzylic hydroxylations.