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  • Portland Press Ltd.  (5)
  • Biology  (5)
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  • Portland Press Ltd.  (5)
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  • Biology  (5)
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  • 1
    Online Resource
    Online Resource
    Metabolic control mechanisms in mammalian systems. Involvement of adenosine 3′:5′-cyclic monophosphate in androgen action
    Portland Press Ltd. ; 1971
    In:  Biochemical Journal Vol. 125, No. 1 ( 1971-11-01), p. 329-342
    Details
    In: Biochemical Journal, Portland Press Ltd., Vol. 125, No. 1 ( 1971-11-01), p. 329-342
    Abstract: 1. The ability of exogenously administered cyclic AMP (adenosine 3′:5′-monophosphate) to exert andromimetic action on certain carbohydrate-metabolizing enzymes was investigated in the rat prostate gland and seminal vesicles. 2. Cyclic AMP, when injected concurrently with theophylline, produced marked increases in hexokinase, phosphofructokinase, glyceraldehyde phosphate dehydrogenase, pyruvate kinase, and two hexose monophosphate-shunt enzymes, as well as α-glycerophosphate dehydrogenase activity in accessory sexual tissues of castrated rats. The 6-N,2′-O-dibutyryl analogue of cyclic AMP caused increases of enzyme activity that were greater than those induced by the parent compound. 3. Time-course studies demonstrated that, whereas significant increases in the activities of most enzymes occurred within 4h after the injection of cyclic AMP, maximal increases were attained at 16–24h. 4. Increase in the activity of the various prostatic and vesicular enzymes was dependent on the dose of cyclic AMP; in most instances, 2.5mg of the cyclic nucleotide/rat was sufficient to elicit a statistically significant response. 5. Administration of cyclic AMP and theophylline also produced stimulation of enzyme activities in secondary sexual tissues of immature rats. 6. Cyclic AMP and theophylline did not affect significantly any of the enzymes studied in hepatic tissue. 7. Stimulation of various carbohydrate-metabolizing enzymes in the prostate gland and seminal vesicles by cyclic AMP was independent of adrenal function. 8. Concurrent treatment with actinomycin or cycloheximide prevented the cyclic AMP- and theophylline-induced increases in enzyme activities in both castrated and adrenalectomized–castrated animals. 9. Administration of a single dose of testosterone propionate (5.0mg/100g) to castrated rats caused a significant increase in cyclic AMP concentration in both accessory sexual tissues. 10. In addition, treatment with theophylline potentiated the effects of a submaximal dose of testosterone (1.0mg/100g) on all those prostatic and seminal-vesicular enzymes that are increased by exogenous cyclic AMP. 11. The evidence indicates that cyclic AMP may be involved in triggering the known metabolic actions of androgens on secondary sexual tissues of the rat.
    Type of Medium: Online Resource
    ISSN: 0306-3283
    URL: Article
    DOI: 10.1042/bj1250329
    RVK:
    WA 15000
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 1971
    detail.hit.zdb_id: 1473095-9
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  • 2
    Online Resource
    Online Resource
    A study of 3′:5′-cyclic mononucleotide-dependent protein kinase from canine prostate glands
    Portland Press Ltd. ; 1974
    In:  Biochemical Journal Vol. 144, No. 2 ( 1974-11-15), p. 377-383
    Details
    In: Biochemical Journal, Portland Press Ltd., Vol. 144, No. 2 ( 1974-11-15), p. 377-383
    Abstract: 1. An adenosine 3′:5′-cyclic monophosphate (cyclic AMP)-dependent protein kinase, located predominantly in the cytosol, was studied in canine prostate. 2. The enzyme exhibited cyclic AMP-binding activity, and could be isolated by chromatography on diethylaminoethyl cellulose. 3. The enzyme was maximally stimulated (fourfold) by 1μm-cyclic AMP, and half-maximal activation of the enzyme was observed in presence of 50nm-cyclic AMP. 4. Equilibrium studies at pH5.0 indicated the presence of one major class of binding site for cyclic AMP, with an association constant of approx. 108m-1. 5. Stimulation of the enzyme was also observed with the 3′:5′-cyclic monophosphate derivatives of cytidine, inosine, guanosine and uridine as well as with dibutyryl cyclic AMP, but higher concentrations of these cyclic nucleotides were required to provide the same degree of activation as that seen with cyclic AMP. 6. Comparing α-casein, protamine and different histone subfractions as substrates, highest cyclic AMP stimulation was demonstrated with histones. 7. Although maximum velocity of the enzyme was enhanced approximately fivefold in presence of cyclic AMP, kinetic studies indicated that the apparent Km for histone (0.5mg/ml) remained the same whether determined in the presence or absence of the cyclic nucleotide. 8. In addition, cyclic AMP did not significantly change the apparent Km for ATP (1.2×10-5m). 9. The purified enzyme showed an absolute requirement for bivalent metal ion. Substitution of Mn2+for Mg2+decreased basal protein kinase activity as well as the stimulation noted with cyclic AMP. Similarly, the basal activity was lowered when Mg2+was replaced by Ca2+and cyclic AMP produced only little stimulation of the prostatic enzyme.
    Type of Medium: Online Resource
    ISSN: 0306-3283
    URL: Article
    DOI: 10.1042/bj1440377
    RVK:
    WA 15000
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 1974
    detail.hit.zdb_id: 1473095-9
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  • 3
    Online Resource
    Online Resource
    Metabolic control mechanisms in mammalian systems. Hormonal regulation of phosphofructokinase in the rat prostate and seminal vesicles
    Portland Press Ltd. ; 1968
    In:  Biochemical Journal Vol. 110, No. 4 ( 1968-12-01), p. 703-711
    Details
    In: Biochemical Journal, Portland Press Ltd., Vol. 110, No. 4 ( 1968-12-01), p. 703-711
    Abstract: 1. The hormonal regulation of phosphofructokinase was investigated in the accessory reproductive organs of the orchidectomized rat. 2. Phosphofructokinase activities declined to 51% and 47% in the prostate and 9% and 6% of the normal values in seminal vesicles 4 and 8 weeks after castration respectively. Administration of testosterone (100μg./100g. body wt.) for 3 days reversed substantially the effects of orchidectomy, and phosphofructokinase activity increased to 173% in the prostate and 536% in seminal vesicles as compared with the values of castrated controls. 3. Time-course studies demonstrated that after a single injection of testosterone (5mg./100g. body wt.) phosphofructokinase activity was maximally elevated to 236% in the prostate and 342% in seminal vesicles at 24hr. 4. Dose–response studies revealed that 2·5mg. of testosterone propionate/100g. body wt. was the minimal amount necessary to induce significant increases in enzyme activity in both accessory sex organs; maximal increases were obtained with a dose of 5mg./100g. body wt. 5. The observed enzyme increases induced by testosterone were inhibited by the simultaneous administration of oestradiol-17β, and phosphofructokinase activity in this group of rats remained at 97% in the prostate and 137% of the control values in seminal vesicles. Oestradiol-17β by itself failed to produce any significant effect on enzyme activity in either of these secondary sexual tissues. 6. The nature of the testosterone-induced increases in phosphofructokinase activity was studied by using a variety of inhibitors of RNA and protein synthesis. Cycloheximide, 5-fluorouracil and ethionine largely blocked the androgen-stimulated rise in enzyme activity observed 24hr. after steroid injection. The inhibitory effect of ethionine was completely reversed by the simultaneous administration of methionine. 7. Actinomycin, which is known to inhibit the synthesis of messenger RNA as well as the synthesis of other cellular RNA fractions, when given simultaneously with the hormone, also inhibited the testosterone-induced increases in prostatic and seminal-vesicular phosphofructokinase. However, when the antibiotic was given 6 or 12hr. after injection of the steroid, practically no inhibition of phosphofructokinase induction was obtained. This indicates that, once the enzyme-forming machinery is turned on and allowed to operate for a few hours, actinomycin is incapable of reversing the hormone-induced enzyme responses. 8. The results presented suggest that new RNA and protein synthesis may be involved in the observed androgen-induced increases in phosphofructokinase activity in the prostate and seminal vesicles of the orchidectomized rat.
    Type of Medium: Online Resource
    ISSN: 0306-3283
    URL: Article
    DOI: 10.1042/bj1100703
    RVK:
    WA 15000
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 1968
    detail.hit.zdb_id: 1473095-9
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  • 4
    Online Resource
    Online Resource
    Characterization of a novel glutathione S -transferase isoenzyme from mouse lung and liver having structural similarity to rat glutathione S -transferase 8-8
    Portland Press Ltd. ; 1991
    In:  Biochemical Journal Vol. 278, No. 3 ( 1991-09-15), p. 793-799
    Details
    In: Biochemical Journal, Portland Press Ltd., Vol. 278, No. 3 ( 1991-09-15), p. 793-799
    Abstract: In mouse lung, glutathione S-transferase (GST, EC 2.5.1.18) isoenzymes belonging to the three major known classes, Alpha, Mu and Pi, have been previously characterized, along with an isoenzyme (pI 5.7) that could not be identified with the Alpha, Mu or Pi classes of GSTs. In the present studies we have demonstrated that this isoenzyme is also expressed in liver. Its structural, kinetic, and immunological properties have been determined and compared with those of the three classes of GSTs. GST 5.7 has a subunit molecular mass of 23 kDa, which is intermediate between that of the previously characterized Alpha (25 kDa) and Pi (22.5 kDa) class GST subunits of mouse lung. Comparison of peptide maps of GST 5.7 with those representative of Alpha, Mu and Pi class GST isoenzymes of mouse lung showed that it had a distinct peptide fragmentation pattern. Kinetic and immunological properties of GST 5.7 were also distinct from other mouse GST isoenzymes belonging to the Alpha, Mu or Pi classes. N-Terminal amino-acid-sequence analysis of a 6 kDa fragment generated by CNBr digestion of mouse lung GST 5.7 revealed a 15-residue sequence that was distinct from sequences of known Alpha, Mu and Pi class mouse GSTs. The sequence, however, matched with the sequence of rat GST 8-8 between amino acid residues 106 and 120 with a 73% identity. The 6 kDa and 12 kDa fragments generated by CNBr digestion of mouse liver GST 5.7 also gave sequences which matched with those of rat GST 8-8 between positions 106 and 120 and 167 and 186, with a high degree of identity. These studies suggest that mouse GST 5.7 structurally corresponds to rat GST 8-8 and belongs to the Alpha class.
    Type of Medium: Online Resource
    ISSN: 0264-6021 , 1470-8728
    URL: Article
    DOI: 10.1042/bj2780793
    RVK:
    WA 15000
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 1991
    detail.hit.zdb_id: 1473095-9
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Independent segregation of glutathione S -transferase and fatty acid ethyl ester synthase from pancreas and other human tissues
    Portland Press Ltd. ; 1991
    In:  Biochemical Journal Vol. 275, No. 2 ( 1991-04-15), p. 507-513
    Details
    In: Biochemical Journal, Portland Press Ltd., Vol. 275, No. 2 ( 1991-04-15), p. 507-513
    Abstract: Glutathione S-transferase (GST) isoenzymes of human pancreas were purified, characterized and evaluated for their possible role in the metabolism of ethanol. Human pancreas has at least two GST isoenzymes belonging to the Alpha class (pI 8.8 and 8.1), one belonging to the Mu class (pI 6.4) and one belonging to the Pi class (pI 4.9). During the purification of GSTs from pancreas as well as from heart, liver, lung, brain and muscle, the fatty acid ethyl ester synthase (FAEES) activity was monitored in order to evaluate the role of GSTs in metabolism of ethanol, as suggested in earlier studies. Both t.l.c. and h.p.l.c. were used to identify ethyl oleate in reaction mixtures to monitor FAEES activity. During the purification of GSTs with the use of affinity chromatography on GSH linked to epoxy-activated Sepharose 6B, FAEES and GST activities from each of these tissues segregated independently. Purified GST isoenzymes from these tissues did not exhibit any FAEES activity. Antibodies raised against Pi-class GST, as expected, immunoprecipitated most of the GST activity of brain and heart without precipitating FAEES activity. These results suggest that human GST isoenzymes belonging to the Alpha, Mu and Pi classes do not express FAEES activity. The independent segregation of GST and FAEES activities was further demonstrated by monitoring GST activity during the purification of FAEES from pancreas. It was found that purified FAEES had no GST activity towards 1-chloro-2,4-dinitrobenzene and a number of other electrophilic substrates. Results of these studies demonstrate that FAEES and GSTs are distinct proteins.
    Type of Medium: Online Resource
    ISSN: 0264-6021 , 1470-8728
    URL: Article
    DOI: 10.1042/bj2750507
    RVK:
    WA 15000
    Language: English
    Publisher: Portland Press Ltd.
    Publication Date: 1991
    detail.hit.zdb_id: 1473095-9
    SSG: 12
    Location Call Number Limitation Availability
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