The phenylthiourea is a competitive inhibitor of the enzymatic oxidation of DOPA by phenoloxidase

Ryazanova, A. D.; Alekseev, A. A.; Slepneva, Irina A.

doi:10.3109/14756366.2011.576010

Cited by 51 publications

(37 citation statements)

References 33 publications

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“…Phenylthiourea (PTU) Feeding-PTU is a strong PO inhibitor (18). It was dissolved in autoclaved water, and saturated PTU was filtered to remove bacteria.…”

Section: Methodsmentioning

confidence: 99%

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Hindgut Innate Immunity and Regulation of Fecal Microbiota through Melanization in Insects

Shao

Yang

et al. 2012

Journal of Biological Chemistry

105

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Background: Many insects eat green leaves but excrete black feces using an unknown mechanism. Results: Hindgut cells produce prophenoloxidase and secrete it into the hindgut content. Conclusion: Prophenoloxidase induces the hindgut content and feces melanization by which bacteria flora are reduced. Significance: This is a first-time disclosure of the enigma of insect black feces and its biological significance.

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“…Phenylthiourea (PTU) Feeding-PTU is a strong PO inhibitor (18). It was dissolved in autoclaved water, and saturated PTU was filtered to remove bacteria.…”

Section: Methodsmentioning

confidence: 99%

“…6A). Thus PTU, a strong PO inhibitor (18), obviously prevented the feces from turning black. When silkworm larvae were placed on ice after bleeding, HG1 content became black within 20 min in vivo.…”

Section: Ppo Is Produced By Hindgut Cells But Not Contamination From mentioning

confidence: 99%

Hindgut Innate Immunity and Regulation of Fecal Microbiota through Melanization in Insects

Shao

Yang

et al. 2012

Journal of Biological Chemistry

105

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“…CPC induces a confirmation change in prophenoloxidase, exposing the catalytic site of active PO (Hall et al, 1995). The addition of phenylthiocarbamide (Sigma-Aldrich), a potent inhibitor of PO (Ryazanova et al, 2012), prevented a change in absorbance of the reaction mixture, suggesting that the action of CPC was specific for prophenoloxidase. In addition, no change in absorbance was measured when hemolymph was excluded from the well, indicating that the observed activation was not an artifact of CPC A simplified schematic of the Manduca sexta immune system (see Jiang, 2008;Jiang et al, 2010;Zhang et al, 2011;Christen et al, 2012;Chevignon et al, 2015) featuring the immune components assessed in this study.…”

Section: Immune Assaysmentioning

confidence: 99%

Reconfiguration of the immune system network during food limitation in the caterpillarManduca sexta

Adamo

Davies

Easy

et al. 2016

Journal of Experimental Biology

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Dwindling resources might be expected to induce a gradual decline in immune function. However, food limitation has complex and seemingly paradoxical effects on the immune system. Examining these changes from an immune system network perspective may help illuminate the purpose of these fluctuations. We found that food limitation lowered long-term (i.e. lipid) and short-term (i.e. sugars) energy stores in the caterpillar Manduca sexta. Food limitation also: altered immune gene expression, changed the activity of key immune enzymes, depressed the concentration of a major antioxidant (glutathione), reduced resistance to oxidative stress, reduced resistance to bacteria (Grampositive and -negative bacteria) but appeared to have less effect on resistance to a fungus. These results provide evidence that food limitation led to a restructuring of the immune system network. In severely food-limited caterpillars, some immune functions were enhanced. As resources dwindled within the caterpillar, the immune response shifted its emphasis away from inducible immune defenses (i.e. those responses that are activated during an immune challenge) and increased emphasis on constitutive defenses (i.e. immune components that are produced consistently). We also found changes suggesting that the activation threshold for some immune responses (e.g. phenoloxidase) was lowered. Changes in the configuration of the immune system network will lead to different immunological strengths and vulnerabilities for the organism.

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“…Under this assumption, the addition of a competitive inhibitor of PO, notably PTU 28,29 , should suppress PO-mediated oxidation of NO. It is based on the reported data that PTU bounds to both the copper ions at the active site of catechol-oxidase 30 .…”

Section: Nitric Oxide Oxidation In the Presence Of Pomentioning

confidence: 99%

Dual effect of nitric oxide on phenoloxidase-mediated melanization

Sanzhaeva

Vorontsova

Glazachev

et al. 2015

Journal of Enzyme Inhibition and Medicinal Chemistry

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The study has demonstrated a dual effect of nitric oxide on phenoloxidase (PO)-mediated DOPA oxidation and melanization process. NO generated at low rates proportionally increased in PO-mediated DOPA oxidation. Competitive PO inhibitor, phenylthiourea, resulted in significant inhibition of NO-mediated DOPA oxidation. Further analysis using fluorescent and EPR methods demonstrated that the effect of NO on DOPA oxidation is explained by oxidation of NO to NO 2 at the active site of PO followed by oxidation of DOPA by NO 2 . On the contrary, the bolus addition of NO gas solution resulted in a significant decrease in observed PO activity. Similar dose-dependent effect of NO was observed for the insect's haemocytes quantified as percentage of melanized cells after treatment with nitric oxide. In conclusion, the results of the study suggest that NO may have a significant regulatory role on melanization process in invertebrates as well as in human and result in protective or damaging effects.

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The phenylthiourea is a competitive inhibitor of the enzymatic oxidation of DOPA by phenoloxidase

Cited by 51 publications

References 33 publications

Hindgut Innate Immunity and Regulation of Fecal Microbiota through Melanization in Insects

Hindgut Innate Immunity and Regulation of Fecal Microbiota through Melanization in Insects

Reconfiguration of the immune system network during food limitation in the caterpillarManduca sexta

Dual effect of nitric oxide on phenoloxidase-mediated melanization

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