<i>In vitro</i> enzyme activity and <i>in vivo</i> healing activity of the protein extract from pineapple peel

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

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Hereditary Nonspherocytic Hemolysis With Erythrocyte Phosphofructokinase Deficiency

Blood ◽

10.1182/blood.v39.3.415.415 ◽

1972 ◽

Vol 39 (3) ◽

pp. 415-425 ◽

Cited By ~ 25

Author(s):

Larry Waterbury ◽

Eugene P. Frenkel

Keyword(s):

Enzyme Activity ◽

Adenosine Triphosphate ◽

Lactate Production ◽

Kinetic Studies ◽

Glycogen Storage ◽

Muscle Disease ◽

Phosphofructokinase Activity ◽

Phosphofructokinase Deficiency

Abstract Hereditary nonspherocytic hemolysis associated with abnormal erythrocyte phosphofructokinase activity was demonstrated in a young man. Enzyme activity in the propositus, his mother, and maternal grandmother was approximately 60% of normal controls. There was markedly increased lability of enzyme activity on in vitro storage. Kinetic studies revealed increased sensitivity to adenosine triphosphate inhibition. Erythrocyte adenosine triphosphate levels were depressed. The absence of muscle disease and the presence of normal in vivo lactate production following ischemic exercise differentiated this kindred from those with Type VII glycogen storage disease.

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Stimulation in vitro of vitamin B12-dependent methionine synthase by polyamines

Biochemical Journal ◽

10.1042/bj3160661 ◽

1996 ◽

Vol 316 (2) ◽

pp. 661-665 ◽

Cited By ~ 10

Author(s):

Susan H. KENYON ◽

Anna NICOLAOU ◽

Tamara AST ◽

William A. GIBBONS

Keyword(s):

Enzyme Activity ◽

Vitamin B12 ◽

Cell Signalling ◽

Methionine Synthase ◽

Polyamine Metabolism ◽

Physiological Concentration ◽

Methylation Pathway ◽

Important Enzyme

Vitamin B12-dependent methionine synthase is an important enzyme for sulphur amino acid, folate polyamine metabolism, S-adenosylmethionine metabolism and also in the methylation pathway of DNA, RNA, proteins and lipids. Consequently, studies aiming at exploring the control and regulation of methionine synthase are of particular interest. Here we report the modulation of enzyme activity in vitro by polyamines. Although putrescine, cadaverine, spermine and spermidine all stimulated enzyme activity, the last two were the most potent, causing increases in enzyme activity up to 400%. The EC50 for spermine was determined as 8 μM and for spermidine 40 μM. The physiological concentration for spermine has been reported to be 15–19 μM. Spermine was found to increase both the Km and the Vmax with respect to methyltetrahydrofolate for the enzyme. These data support the hypothesis that spermine and spermidine are feedback regulators of methionine synthase both in vivo and in vitro and are consistent with the polyamines' regulating cell signalling pathways.

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Functional cytochrome P450 1A enzymes are induced in mouse and human islets following pollutant exposure

Diabetologia ◽

10.1007/s00125-019-05035-0 ◽

2019 ◽

Vol 63 (1) ◽

pp. 162-178 ◽

Cited By ~ 4

Author(s):

Muna Ibrahim ◽

Erin M. MacFarlane ◽

Geronimo Matteo ◽

Myriam P. Hoyeck ◽

Kayleigh R. C. Rick ◽

...

Keyword(s):

Enzyme Activity ◽

Insulin Secretion ◽

Beta Cell ◽

Human Islets ◽

High Dose ◽

Single High Dose ◽

Direct Exposure ◽

Mouse Islets

Abstract Aims/hypothesis Exposure to environmental pollution has been consistently linked to diabetes incidence in humans, but the potential causative mechanisms remain unclear. Given the critical role of regulated insulin secretion in maintaining glucose homeostasis, environmental chemicals that reach the endocrine pancreas and cause beta cell injury are of particular concern. We propose that cytochrome P450 (CYP) enzymes, which are involved in metabolising xenobiotics, could serve as a useful biomarker for direct exposure of islets to pollutants. Moreover, functional CYP enzymes in islets could also impact beta cell physiology. The aim of this study was to determine whether CYP1A enzymes are activated in islets following direct or systemic exposure to environmental pollutants. Methods Immortalised liver (HepG2) and rodent pancreatic endocrine cell lines (MIN6, βTC-6, INS1, α-TC1, α-TC3), as well as human islets, were treated in vitro with known CYP1A inducers 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3-methylcholanthrene (3-MC). In addition, mice were injected with either a single high dose of TCDD or multiple low doses of TCDD in vivo, and islets were isolated 1, 7 or 14 days later. Results CYP1A enzymes were not activated in any of the immortalised beta or alpha cell lines tested. However, both 3-MC and TCDD potently induced CYP1A1 gene expression and modestly increased CYP1A1 enzyme activity in human islets after 48 h. The induction of CYP1A1 in human islets by TCDD was prevented by cotreatment with a cytokine mixture. After a systemic single high-dose TCDD injection, CYP1A1 enzyme activity was induced in mouse islets ~2-fold, ~40-fold and ~80-fold compared with controls after 1, 7 and 14 days, respectively, in vivo. Multiple low-dose TCDD exposure in vivo also caused significant upregulation of Cyp1a1 in mouse islets. Direct TCDD exposure to human and mouse islets in vitro resulted in suppressed glucose-induced insulin secretion. A single high-dose TCDD injection resulted in lower plasma insulin levels, as well as a pronounced increase in beta cell death. Conclusions/interpretation Transient exposure to TCDD results in long-term upregulation of CYP1A1 enzyme activity in islets. This provides evidence for direct exposure of islets to lipophilic pollutants in vivo and may have implications for islet physiology.

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THE DETECTION OF A VIRAL INTERFERING SUBSTANCE IN THE SHOPE PAPILLOMA AND THE Vx7 AND Vx2 CARCINOMAS

Journal of Experimental Medicine ◽

10.1084/jem.126.5.887 ◽

1967 ◽

Vol 126 (5) ◽

pp. 887-897

Author(s):

Deborah Pavan Langston ◽

Leslie H. Sobin

Keyword(s):

Nucleic Acid ◽

Fluorescent Antibody ◽

In Vitro Assay ◽

Moderate Activity ◽

Protein Extract ◽

Viral Nucleic Acid ◽

Vitro Assay ◽

Protein Coat

In vivo assay of Shope papilloma protein extract and in vitro assay of extracts from Shope papilloma, Vx7 and Vx2 carcinomas showed strong interferon-like activity in the papilloma and moderate activity in the carcinomas. The interpretation is that the presence of viral nucleic acid in all three tumors stimulated the production of this substance even though fluorescent antibody studies reveal the protein coat only in the papilloma and Vx7.

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XP-828L (Dermylex), a new whey protein extract with potential benefit for mild to moderate psoriasisThis article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products.

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y07-084 ◽

2007 ◽

Vol 85 (9) ◽

pp. 943-951 ◽

Cited By ~ 6

Author(s):

Réjean Drouin ◽

Éric Lamiot ◽

Kim Cantin ◽

Sylvie F. Gauthier ◽

Yves Pouliot ◽

...

Keyword(s):

Whey Protein ◽

Mechanism Of Action ◽

Natural Health Products ◽

Concomitant Treatment ◽

Natural Health ◽

Protein Extract ◽

Murine Splenocytes ◽

Health Products

Natural health products (NHPs) or complementary and alternative medicine (CAM) are commonly used to prevent disorders or support the usual treatments of many diseases. XP-828L, a whey protein extract, has demonstrated potential benefits for the treatment of mild to moderate psoriasis. The aim of this study was to analyze further clinical data that demonstrated the clinical benefits and safety of the XP-828L in patients with psoriasis and the potential mechanism of action of this product in vitro. Oral administration (2.5 g, twice a day, over 112 days) of XP-828L in 42 human subjects with mild to moderate psoriasis improved their PGA scores (physician’s global assessment). Moreover, no significant changes in haematology or hepatic and renal parameters were observed throughout the study period, indicating the safety of the product. In vitro experiments showed that XP-828L decreased the proliferation of concanavalin A (ConA)-stimulated murine splenocytes and their production of interleukin (IL)-2 and interferon (IFN)-γ. Although the in vivo mechanism of action of XP-828L remains unknown, XP-828L represents an NHP to be used as an alternative or concomitant treatment for mild to moderate psoriasis and potentially for other immune-mediated diseases.

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The Alternative Route to Heme in the Methanogenic ArchaeonMethanosarcina barkeri

Archaea ◽

10.1155/2014/327637 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 26

Author(s):

Melanie Kühner ◽

Kristin Haufschildt ◽

Alexander Neumann ◽

Sonja Storbeck ◽

Judith Streif ◽

...

Keyword(s):

Enzyme Activity ◽

Feedback Regulation ◽

Methanosarcina Barkeri ◽

Heme Biosynthesis ◽

Alternative Route ◽

Activity Assay ◽

Enzyme Activity Assay ◽

Living Organisms

In living organisms heme is formed from the common precursor uroporphyrinogen III by either one of two substantially different pathways. In contrast to eukaryotes and most bacteria which employ the so-called “classical” heme biosynthesis pathway, the archaea use an alternative route. In this pathway, heme is formed from uroporphyrinogen III via the intermediates precorrin-2, sirohydrochlorin, siroheme, 12,18-didecarboxysiroheme, and iron-coproporphyrin III. In this study the heme biosynthesis proteins AhbAB, AhbC, and AhbD fromMethanosarcina barkeriwere functionally characterized. Using anin vivoenzyme activity assay it was shown that AhbA and AhbB (Mbar_A1459 and Mbar_A1460) together catalyze the conversion of siroheme into 12,18-didecarboxysiroheme. The two proteins form a heterodimeric complex which might be subject to feedback regulation by the pathway end-product heme. Further, AhbC (Mbar_A1793) was shown to catalyze the formation of iron-coproporphyrin IIIin vivo. Finally, recombinant AhbD (Mbar_A1458) was produced inE. coliand purified indicating that this protein most likely contains two [4Fe-4S] clusters. Using anin vitroenzyme activity assay it was demonstrated that AhbD catalyzes the conversion of iron-coproporphyrin III into heme.

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Inactivation in Vitro of Lactate Dehydrogenase-5 in Blood

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456327701400109 ◽

1977 ◽

Vol 14 (1-6) ◽

pp. 48-52 ◽

Cited By ~ 1

Author(s):

A. R. Qureshi ◽

J. H. Wilkinson

Keyword(s):

Enzyme Activity ◽

Lactate Dehydrogenase ◽

Whole Blood ◽

Rabbit Muscle ◽

Muscle Lactate ◽

Rabbit Blood

During incubation with rabbit blood in vitro rabbit-muscle lactate dehydrogenase-5 was inactivated at a rate similar to that observed in vivo. By contrast plasma and plasma containing erythrocytes had no effect on the enzyme activity, but plasma containing leucocytes inactivated the enzyme at the same rate as whole blood. The results obtained support the concept that intravascular inactivation accounts for the disappearance of enzymes from the circulation.

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Short-Term Retinoic Acid Treatment Increases In Vivo, but Decreases In Vitro, Epidermal Transglutaminase-K Enzyme Activity and Immunoreactivity

Journal of Investigative Dermatology ◽

10.1111/1523-1747.ep12616626 ◽

1992 ◽

Vol 99 (3) ◽

pp. 283-288 ◽

Cited By ~ 22

Author(s):

Christopher E M Griffiths ◽

Dean S Rosenthal ◽

Ambati P Reddy ◽

James T Elder ◽

Anders. Astrom ◽

...

Keyword(s):

Enzyme Activity ◽

Retinoic Acid ◽

Acid Treatment ◽

Short Term ◽

Retinoic Acid Treatment ◽

Epidermal Transglutaminase

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Diamine-induced inhibition of liver ornithine decarboxylase

Biochemical Journal ◽

10.1042/bj1770063 ◽

1979 ◽

Vol 177 (1) ◽

pp. 63-69 ◽

Cited By ~ 28

Author(s):

Arja Kallio ◽

Monica Löfman ◽

Hannu Pösö ◽

Juhani Jänne

Keyword(s):

Enzyme Activity ◽

Ornithine Decarboxylase ◽

Enzyme Inhibitor ◽

Decarboxylase Activity ◽

Enzyme Protein ◽

Intracellular Degradation ◽

Ornithine Decarboxylase Activity ◽

Normal Rat

Re!peated injections of 1,3-diaminopropane, a potent inhibitor of mammalian ornithine decarboxylase, induced protein-synthesis-dependent formation of macromolecular inhibitors or ‘antienzymes’ [Heller, Fong & Canellakis (1976) Proc. Natl. Acad. Sci. U.S.A.73, 1858–1862] to ornithine decarboxylase in normal rat liver. Addition of the macromolecular inhibitors, produced in response to repeated injections of diaminopropane, to active ornithine decarboxylase in vitro resulted in a profound loss of the enzyme activity, which, however, could be partly recovered after passage of the enzyme–inhibitor mixture through a Sephadex G-75 columin in the presence of 0.4m-NaCl. This treatment also resulted in the appearance of free inhibitor. In contrast with the separation of the enzyme and inhibitory activity after combination in vitro, it was not possible to re-activate, by using identical conditions of molecular sieving, any inhibited ornithine decarboxylase from cytosol fractions obtained from animals injected with diaminopropane. However, the idea that injection of various diamines, also in vivo, induces acute formation of macromolecular inhibitors, which reversibly combine with the enzyme, was supported by the finding that the ornithine decarboxylase activity remaining after diaminopropane injection appeared to be more stable to increased ionic strength than the enzyme activity obtained from somatotropin-treated rats. Incubation of the inhibitory cytosol fractions with antiserum to ornithine decarboxylase did not completely abolish the inhibitory action of either the cytosolic inhibitor or the antibody. A single injection of diaminopropane produced an extremely rapid decay of liver ornithine decarboxylase activity (half-life about 12min), which was comparable with, or swifter than, that induced by cycloheximide. However, although after cycloheximide treatment the amount of immunotitrable ornithine decarboxylase decreased only slightly more slowly than the enzyme activity, diaminopropane injection did not decrease the amount of the immunoreactive protein, but, on the contrary, invariably caused a marked increase in the apparent amount of antigen, after some lag period. The diamine-induced increase in the amount of the immunoreactive enzyme protein could be totally prevented by a simultaneous injection of cycloheximide. These results are in accord with the hypothesis that various diamines may result in rapid formation of macromolecular inhibitors to ornithine decarboxylase in vivo, which, after combination with the enzyme, abolish the catalytic activity but at the same time prevent the intracellular degradation of the enzyme protein.

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