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1.
A simple and very sensitive method for the separation of 4-hydroxyacetanilide, 3-hydroxyacetanilide, 2-hydroxyacetanilide, and acetanilide was developed with the use of high-pressure liquid chromagraphy. Each of these phenolic derivatives can be separated completely from acetanilide and from one another. A simple assay for “acetanilide 4-hydroxylase activity” is thus described. The limit of sensitivity for cytochrome P-450-mediated acetanilide 4-hydroxylase activity is estimated to be 1.0 pmol/min/mg microsomal protein, thereby allowing this assay to be useful in detecting monooxygenase activity in “low level” nonhepatic tissues. Hepatic acetanilide 4-hydroxylase activity is induced about fourfold in mice by 3-methylcholanthrene. Although acetanilide 2-hydroxylase activity is about seven times lower than the 4-hydroxylase activity, the 2-hydroxylase is also induced about three- or fourfold in mice by 3-methylcholanthrene. The “2-hydroxylase activity” cannot, however, be strictly quantitated under the conditions described herein. The Km values of both the 3-methylcholanthrene-induced and control 4-hydroxylase activity are about 0.55 mm; Vmax values for 3-methylcholanthrene-treated and control mice, respectively, are 4.9 ± 1.1 and 1.1 ± 0.31 nmol/min/mg microsomal protein. The 4-hydroxylase in the liver of both 3-methylcholanthrene-treated and control mice appears to represent two or more catalytic activities, i.e., two or more forms of P-450 having widely differing affinities for the substrate acetanilide. 相似文献
2.
The mitochondrial phenotype of and other extra-nuclear mutants is known to predominate over that of wild type in heteroplasms. This phenomenon was investigated in heterokaryons using normally occurring strain differences in restriction enzyme patterns to distinguish wild-type and mitochondrial DNAs. Each of ten independent heterokaryons eventually showed the phenotype as judged by slow growth rate and deficiency of 19 S RNA. Six heterokaryons contained mitochondrial DNAs with restriction enzyme patterns of the parent whereas four contained DNAs which lacked restriction enzyme fragments characteristic of the parent. The latter may be recombinants of wild-type and mitochondrial DNA. 相似文献
3.
O Brown F Yein D Boehme L Foudin C S Song 《Biochemical and biophysical research communications》1979,91(3):982-990
Quinolinate phosphoribosyl transferase was rapidly inactivated in exposed to hyperbaric oxygen. The enzyme is essential for de novo biosynthesis of NAD in and man. Because of its sensitivity and essentiality, inactivation of this enzyme is proposed as a significant mechanism of cellular oxygen toxicity. Niacin which enters the NAD biosynthetic pathway below the oxygen-poisoned enzyme provided significant protection against the decrease in pyridine nucleotides and the growth inhibition from hyperoxia in and could be useful in cases of human oxygen poisoning. 相似文献
4.
E A Meighen I G Bogacki A Bognar G A Michaliszyn 《Biochemical and biophysical research communications》1976,69(2):423-430
Bioluminescence rises very rapidly in the later stages of growth of due to the induction of luciferase activity. This enzyme catalyzes the oxidation of FMNH2 and a long chain aliphatic aldehyde resulting in the emission of light. The present experiments report the discovery of an aldehyde dehydrogenase in which is remarkably similar to luciferase in its specificity for long chain aliphatic aldehydes. Furthermore, the activity of this enzyme is shown to be induced at the same time as luciferase thus providing strong evidence for a functional implication of aldehyde dehydrogenase in the bioluminescent system of . 相似文献
5.
The cytochrome oxidase (EC 1.9.3.1) of HB8 was isolated from the membrane fraction, and was highly purified. The oxidase contained heme and heme as the prosthetic groups. The purified preparation showed a single band in polyacrylamide gel electrophoresis, and three major polypeptides with apparent molecular weights of 52,000, 37,000 and 29,000 were observed in the presence of sodium dodecyl sulfate. The enzyme reacted rapidly with cytochrome c-552. The oxidation of cytochrome -555,549 by the enzyme was very slow, and was stimulated by the addition of cytochrome -552. The enzyme was highly stable to heat. 相似文献
6.
Charles D. Boyer Jack Preiss 《Biochemical and biophysical research communications》1978,80(1):169-175
Purification of starch branching enzymes from kernels of two nonlinked mutants of maize, and , showed the basis of the two mutations to be associated with branching enzymes I and IIb, respectively. Branching enzyme I from kernels purified as nonmutant branching enzyme I, but had an altered pattern of activity when amylose was used as a substrate. In addition to the typical fall in absorbance at high wavelengths (550–700 nm) of the amylose-iodine complex, branching of amylose by branching enzyme I caused an increase in absorbance at low wavelengths (400–550 nm). Branching enzyme IIb was undetected in extracts of kernels, while branching enzymes I and IIa appeared unaltered. Low umprimed starch synthase activity was also observed in DEAE-cellulose fractions of maize, but this activity was regenerated by the addition of any branching enzyme. 相似文献
7.
-Octopamine was characterized as substrate for monoamine oxidase (MAO) in rat brain and liver mitochondria. The m and max values of the brain enzyme were 735 μM and 32.5 nmoles/mg protein/30 min, and those of the liver enzyme 351 μM and 125 nmoles/mg protein/30 min, respectively. The inhibition experiments with clorgyline and deprenyl showed that -octopamine was a common substrate for type A and type B MAO, though a major part of the activity was due to type A enzyme. 相似文献
8.
A Novel function of cytochrome C (555, Chlorobium thiosulfatophilum) in oxidation of thiosulfate 总被引:2,自引:0,他引:2
Thiosulfate-cytochrome c-551 reductase derived from has been highly purified. The enzyme reduces cytochrome in the presence of thiosulfate while cytochrome -555 of the organism is not reduced by the enzyme. Cytochrome -555 reacts with the enzyme at an appreciable rate only in the presence of cytochrome -551. However, the reduction rate of cytochrome -551 by the enzyme is greatly enhanced on addition of a catalytic amount of cytochrome -555. Therefore, cytochrome -555 seems to function as an effector on thiosulfate-cytochrome -551 reductase as well as it acts as the electron donor to the light-excited chlorobium chlorophylls. 相似文献
9.
K Okazaki 《Biochemical and biophysical research communications》1975,64(1):20-27
Thiamine pyrophosphokinase (E.C. 2.7.6.2.) from was found to require the presence of a non-protein, non-metal compound for its activity. -Inositol was found capable of stimulating the kinase activity in the presumably resolved but otherwise crude sample of the enzyme. The hexytol was also found capable of inducing the enzyme in growing yeast cells. The cultured yeast cells, in which the kinase had been induced, were used as source of the enzyme for its purification. The compound that had been left adsorbed to the final column of DEAE-Sephadex was proved to have a coenzyme activity towards the enzyme and tentatively identified with -inositol 1-pyrophosphate. A sample of synthetic -inositol 1-pyrophosphate was made and its coenzyme activity was observed. 相似文献
10.
P P Hipps M R Eveland M H Laird W R Sherman 《Biochemical and biophysical research communications》1976,68(4):1133-1138
-Inositol:NAD(P)+ oxidoreductase (-inositol oxidoreductase) has been identified in bovine brain. This enzyme elutes from DEAE cellulose with 0.3 M KCl in 50 mM Tris buffer, pH 7.5. Using NADH as cofactor -inosose-2 is reduced selectively to -inositol. With NADPH the enzyme forms both -inositol and -inositol, however, at a lower rate. The enzyme was chromatographed on G-100 Sephadex and found to have an apparent molecular weight of 74,000. This enzyme differs in DEAE binding, molecular weight and cofactor specificity from the previously described -inositol oxidoreductase which utilizes NADPH exclusively to produce 3 fold more -inositol than -inositol. 相似文献
11.
Yoichi Taya Susumu Nishimura 《Biochemical and biophysical research communications》1973,51(4):1062-1068
A new enzyme, which catalyzes the transfer of a methyl group to tRNA to form 5-methylaminomethyl-2-thiouridylate, was isolated from by a procedure including affinity chromatography. The purified enzyme was nearly homogeneous upon disc electrophoresis. Using methyl-deficient tRNAGlu of as substrate, the 5-methylaminomethyl-2-thiouridylate residue synthesized was mostly found in the anticodon loop, showing a coincidence of the modification site with that . 相似文献
12.
Y Orii H Shimada T Nozawa M Hatano 《Biochemical and biophysical research communications》1977,76(4):983-988
A possibility of a heme-heme interaction between the heme and heme moieties in nitrite reductase was examined by using magnetic and natural circular dichroism. The MCD of the heme moiety in the ferric enzyme was similar to that of mammalian ferricytochrome in shape and intensity, whereas in the reduced state the MCD intensity was considerably smaller than that of ferrocytochrome . When the heme moiety was perturbed by the complex formation with CO, imidazole or cyanide as well as by pH changes, the depressed MCD was restored to the MCD level of mammalian ferrocytochrome , accompanying conformational changes around the prosthetic groups. Thus, it was concluded that the heme-heme interaction exists only in the reduced enzyme and that this interaction is released under appropriate conditions. 相似文献
13.
S Friedman 《Biochemical and biophysical research communications》1979,89(4):1328-1333
5-Azacytidine, when added to growing K12, causes a decrease in DNA methylation assayed . This decrease is greater when DNA is used as substrate than when calf thymus DNA is used. The decrease in activity is not due to the inhibition of protein synthesis caused by this drug, since neither chloramphenicol nor rifampin causes a decrease in enzyme activity. The effect is specific for the DNA(cytosine-5)methylase; the methylation of adenine is not affected. The concentration of drug that inhibits the DNA methylase by 50% is the same concentration that inhibits cell growth by 50%. 相似文献
14.
Enzymic degradation of capsular polysaccharide by the depolymerases from azotophage lysates of . , and from a strain of . was examined. The molecular size of the capsular polysaccharide was examined by molecular sieve chromatography both before and after exposure to the capsule depolymerase. The depolymerase appears to attack the polysaccharide substrate in a random fashion which results in polysaccharide fragments of a random size distribution. The ester linkages and hexuronic acids were proportionally the same in all fractions before degradation, but ester linkages were absent from the smaller polysaccharide molecules after enzyme action. The ester linkages were not the substrate bonds broken by the enzyme, but, in the case of some azotophage enzymes, they appeared to play a role in enzyme activity, possibly as recognition sites. 相似文献
15.
Isao Matsui Masaharu Kamei Shuzo Otani Seiji Morisawa Anthony E. Pegg 《Biochemical and biophysical research communications》1982,106(4):1155-1160
Spermidine acetylase activity was detected in extracts prepared from and there was a marked increase in activity over the early period of growth. This increase reached a maximum 3 h after inoculation and was followed by an increase in ornithine decarboxylase activity. The acetylase was also able to use spermine as a substrate, but not putrescine. With spermidine and acetyl-CoA as substrate, the product formed was exclusively N1-acetyl-spermidine. This is the first evidence for the occurrence in bacteria of spermidine-N1-acetyltransferase, an enzyme which has previously been described in mammalian cells. These results suggest that acetylation of spermidine may be involved in the growth of and in the regulation of its polyamine content. 相似文献
16.
F E Ruch D R Kuritzkes E C Lin 《Biochemical and biophysical research communications》1979,91(4):1365-1370
Strains of with fusions between the structural genes and the promoter region of the fumarate reductase system were constructed from a parental strain deleted in the native operon. Like fumarate reductase in wild-type cells, β-galactosidase in these fusion strains is inducible by fumarate, but only under anaerobic conditions. From one of these strains, three classes of mutants altered in the expression of the hybrid operon were isolated. By anaerobic selection for growth on lactose in the absence of fumarate, mutants that synthesize β-galactosidase constitutively both aerobically and anaerobically were obtained. By aerobic selection for growth on lactose in the presence of fumarate, mutants that are inducible in the enzyme both aerobically and anaerobically and mutants that are inducible in the enzyme only aerobically were obtained. The regulatory behaviors of the mutants studied suggest that substrate and respiratory control of the expression of the fumarate reductase complex are mechanistically connected. 相似文献
17.
Sulfite oxidase, a soluble enzyme in mitochondrial intermembrane space, was synthesized as a precursor protein larger than the authentic enzyme when rat liver RNA was translated using reticulocyte lysate. When the translation products were incubated with isolated rat liver mitochondria, the precursor of sulfite oxidase was converted to the size of the mature enzyme. The processed mature enzyme was no longer susceptible to externally added proteases and was extractable by a hypotonic treatment of the mitochondria, suggesting its location in the intermembrane space. When mitochondria were subfractionated, most of the processing activity was recovered in the mitoplast fraction. The import-processing activity of mitochondria was inhibited by CCCP, oligomycin, or atractyloside in the presence of KCN. These results suggest that the import of sulfite oxidase into mitochondrial intermembrane space requires the participation of inner membrane. 相似文献
18.
T Yagi H Kagamiyama M Nozaki 《Biochemical and biophysical research communications》1979,90(2):447-452
Aspartate aminotransferases from pig heart cytosol and mitochondria, B and accepted L-cysteine sulfinate as a good substrate. The mitochondrial isoenzyme and the enzyme showed higher activity toward L-cysteine sulfinate than toward the natural substrates, L-glutamate and L-aspartate. The cytosolic isoenzyme catalyzed the L-cysteine sulfinate transamination at 50% the rate of L-glutamate transamination. The enzyme had the same reactivity toward the three substrates. Antisera against the two isoenzymes and the enzyme inactivated almost completely cysteine sulfinate transamination activity in the crude extracts of pig heart muscle and B, respectively. These results indicate that cysteine sulfinate transamination is catalyzed by aspartate aminotransferase in these cells. 相似文献
19.
J.G. Gavilanes M.A. Lizarbe A.M. Municio M. Oñaderra 《Biochemical and biophysical research communications》1981,101(4):1228-1232
The lipoprotein structure of the fatty acid synthetase complex from Ceratitis capitata has been used as a model to date the claim that phospholipids from membranes assume a cant role in the cell-endotoxin interactions. The enzyme-complex was exposed to a 14C-lipopolysaccharide preparation and the action was followed by a) circular dichroism spectra, b) enzyme activity and c) gel filtration chromatography. It should be sized that the E. coli endotoxin modifies all these properties of the enzyme complex and that a model involving phospholipids and phase transitions has been proposed to account for these tions. 相似文献
20.
Paul K. Tomich G. Robert Greenberg 《Biochemical and biophysical research communications》1973,50(4):1032-1038
Infection by , a temperature-sensitive mutant of gene 42 of phage T4, the structural gene for dCMP hydroxymethylase, previously was shown not to form T4 DNA at nonpermissive temperatures. Yet the enzyme activity was found in extracts. Since inactivation of the enzyme was not reversible, we have examined acid-soluble extracts of cells infected at nonpermissive temperature by for 5-hydroxymethyldCMP in order to determine whether the enzyme functioned . A double mutant of and (5-hydroxymethyldCMP kinase) did not form the nucleotide at nonpermissive temperature, but the control, , formed large quantities. From these results and previous temperature-shift studies it is suggested that the enzyme is normally activated to function between 5 and 8 minutes after infection. 相似文献