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  • 1
    Electronic Resource
    Electronic Resource
    Biosynthesis of dehydro-N-acetyldopamine by a soluble enzyme preparation from the larval cuticle of Sarcophaga bullata involves intermediary formation of N-acetyldopamine quinone and N-acetyldopamine quinone methide (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 15 (1990), S. 237-254 
    Details
    ISSN: 0739-4462
    Keywords: phenoloxidase ; quinone isomerase ; quinone methide isomerase ; β-sclerotization ; quinone methide sclerotization ; side chain desaturation ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The enzymes involved in the side chain hydroxylation and side chain desaturation of the sclerotizing precursor N-acetyldopamine (NADA) were obtained in the soluble form from the larval cuticle of Sarcophaga bullata and the mechanism of the reaction was investigated. Phenylthiourea, a well-known inhibitor of phenoloxidases, drastically inhibited both the reactions, indicating the requirement of a phenoloxidase component. N-acetylcysteine, a powerful quinone trap, trapped the transiently formed NADA quinone and prevented the production of both N-acetylnorepinephrine and dehydro NADA. Exogenously added NADA quinone was readily converted by these enzyme preparations to N-acetylnorepinephrine and dehydro NADA. 4-Alkyl-o-quinone:2-hydroxy-p-quinone methide isomerase obtained from the cuticular preparations converted chemically synthesized NADA quinone to its quinone methide. The quinone methide formed reacted rapidly and nonezymatically with water to form N-acetylnorepinephrine as the stable product. Similarly 4-(2-hydroxyethl)-o-benzoquinone was converted to 3,4-dihydroxyphenyl glycol. When the NADA quinone-quinone isomerase reaction was performed in buffer containing 10% methanol, β-methoxy NADA was obtained as an additional product. Furthermore, the quinones of N-acetylnorepinephrine and 3,4-dihydroxyphenyl glycol were converted to N-acetylarterenone and 2-hydroxy-3′,4′-dihydroxyacetophenone, respectively, by the enzyme. Comparison of nonenzymatic versus enzymatic transformation of NADA to N-acetylnorepinephrine revealed that the enzymatic reaction is at least 100 times faster than the nonezymatic rate. Resolution of the NADA desaturase system on Benzamidine Sepharose and Sephacryl S-200 columns yielded the above-mentioned quinone isomerase and NADA quinone methide:dehydro NADA isomerase. The latter, on reconstitution with mushroom tyrosinase and hemolymph quinone isomerase, catalyzed the biosynthesis of dehydro NADA from NADA with the intermediary formation of NADA quinone and NADA quinone methide.The results are interpreted in terms of the quinone methide model elabrated by our group [Sugumaran: Adv. Insect Physiol. 21 :179-231, 1988; Sugumaran et al.: Arch. Insect Biochem. Physiol. 11 :109,1989] and it i s concluded that the two enzyme p-sclerotization model [Andersen: Insect Biochem. 19:59-67,375-382,1989] is inadequate to account for various observations made on insect cuticle.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940150405
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on the enzymes involved in puparial cuticle sclerotization in Drosophila melanogaster (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 19 (1992), S. 271-283 
    Details
    ISSN: 0739-4462
    Keywords: quinone tanning ; quinone methide sclerotization ; β-sclerotization ; phenoloxidase ; quinone isomerase ; quinone methide isomerase ; dehydro-N-acetyldopamine ; fruit fly ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The properties of cuticular enzymes involved in sclerotization of Drosophila melanogaster puparium were examined. The cuticle-bound phenoloxidase from the white puparium exhibited a pH optimum of 6.5 in phosphate buffer and oxidized a variety of catecholic substrates such as 4-methylcatechol, N-β-alanyldopamine, dopa, dopamine, N-acetyldopamine, catechol, norepinephrine, 3,4-dihydroxyphenylglycol, 3,4-dihydroxylbenzoic acid, and 3,4-dihydroxyphenylacetic acid. Phenoloxidase inhibitors such as potassium cyanide and sodium fluoride inhibited the enzyme activity drastically, but phenylthiourea showed marginal inhibition only. This result, coupled with the fact that syringaldazine served as the substrate for the insoluble enzyme, confirmed that cuticular phenoloxidase is of the “laccase” type. In addition, we also examined the mode of synthesis of the sclerotizing precursor, 1,2-dehydro N-acetyldopamine. Our results indicate that this catecholamine derivative is biosynthesized from N-acetyldopamine through the intermediate formation of N-acetyldopamine quinone and N-acetyldopamine quinone methide as established for Sarcophage bullata [Saul, S. and Sugumaran, M., F.E.B.S. Letters 251, 69-73 (1989)]. Accordingly, successful solubilization and fractionation of cuticular enzymes involved in the introdution of a double bond in the side chain of N-acetyldopamine indicated that they included o-diophenoloxidase, 4-alkyl-o-quinone: p-quinone methide isomerase, and N-acetyldopamine quinone methide: dehydro N-acetyldopamine isomerase and not any side chain desaturase. © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940190406
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of quinone tautomerase activity in the hemolymph of Sarcophaga bullata larvae (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 12 (1989), S. 157-172 
    Details
    ISSN: 0739-4462
    Keywords: insect immunity ; melanization ; prophenoloxidase activation ; quinone methide for mation ; quinone isomerase ; quinone detoxification ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The hemolymph of Sarcophaga bullata larvae was activated with either zymosan or proteolytic enzymes such as chymotrypsin or subtilisin and assayed for phenoloxidase activity by two different assays. While oxygen uptake studies readily attested to the wide specificty of activated phenoloxidase, visible spectral studies failed to confirm the accumulation of quinone products in the case of 4-alkyl substituted catechols such as N-acetyldopamine and N-β-alanyldopamine. Sepharose 6B column chromatography of the activated hemolymph resolved phenoloxidase activity into two fractions, designated as A and B. Peak A possessed typical o-diphenoloxidase (o-diphenol, oxygen oxidoreductase EC 1.10.3.1) activity, while peak B oxidized physiologically important catecholamine derivatives such as N-acetyldopamine, N-acetylnorepinephrine, and N-β-alanyldopamine into N-acetylnorepinephrine, N-acetylarterenone, and N-β-alanylnorepinephrine, respectively, and converted 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxymandelic acid, and 3,4-dihydroxyphenylglycol into 3,4-dihydroxymandelic acid, 3,4-dihydroxybenzaldehyde, and 2-hydroxy-3′,4′-dihydroxyacetophenone, respectively. These transformations are consistent with the conversion of phenoloxidase-generated quinones to quinone methides and subsequent non-enzymatic transformations of quinone methides. Accordingly, Peak B contained both o-diphenoloxidase activity and quinone tautomerase activity. Sepharose 6B column chromatography of unactivated hemolymph resulted in the separation of quinone tautomerase from prophenoloxidase. The tautomerase rapidly converted both chemically made and mushroom tyrosinase-generated quinones to quinone methides. Thus the failure to observe the accumulation of quinones with N-acyl derivatives of dopamine and related compounds in the whole hemolymph is due to the rapid conversion of these long lived toxic quinones to short lived quinone methides. The latter, being unstable, undergo rapid non-enzymatic transformations to form side-chain-oxygenated products that are non-toxic. The possible roles of quinone isomerase and its reaction products - quinone methides - as essential components of sclerotization of cuticle and defense reaction of Sarcophaga bullata are discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940120304
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  • 4
    Electronic Resource
    Electronic Resource
    Prophenoloxidase activation in the hemolymph of Sarcophaga bullata larvae (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 7 (1988), S. 91-103 
    Details
    ISSN: 0739-4462
    Keywords: protease cascade ; protease inhibitor ; melanization ; insect immunity ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Phenoloxidase in the hemolymph of Sarcophaga bullata larvae is present as an inactive proenzyme form. Localization studies indicate that the majority of the prophenoloxidase is present in the plasma fraction whereas only a minor fraction (about 4%) is present in the cellular compartments (hemocytes). Inactive prophenoloxidase can be activated by zymosan, not by either endotoxin or laminarin. This activation process is inhibited by the serine protease inhibitors, benzamidine and p-nitrophenyl-p∼-guanidobenzoate. Exogenously added proteases, such as chymotrypsin and subtilisin, also activated the prophenoloxidase in the whole hemolymph but failed to activate the partially purified proenzyme. However, an activating enzyme isolated from the larval cuticle, which exhibits trypsinlike specificity, activated the partially purified prophenoloxidase. Inhibition studies and activity measurements also revealed the presence of a similar activating enzyme in the hemolymph. Thus, the phenoloxidase system in Sarcophaga bullata larval hemolymph seems to be comprised of a cascade of reactions. An endogenous protease inhibitor isolated from the larvae inhibited chymotrypsin-mediated prophenoloxidase activation but failed to inhibit the cuticular activating enzyme-catalyzed activation. Based on these studies, the roles of prophenoloxidase, endogenous activating proteases, and protease inhibitor in insect immunity are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940070203
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  • 5
    Electronic Resource
    Electronic Resource
    Protease mediated prophenoloxidase activation in the hemolymph of the tobacco hornworm, Manduca sexta (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 5 (1987), S. 1-11 
    Details
    ISSN: 0739-4462
    Keywords: protease inhibitors ; insect immunity ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Endotoxin and laminarin activated prophenoloxidase in the plasma of Manduca sexta hemolymph. Diisopropylfluorophosphate inhibited this activation, suggesting the presence of a serine protease in the activation cascade. Exogenously added proteases such as pronase, chymotrypsin, subtilisin, and thermolysin also activated prophenoloxidase in Manduca plasma. However, these enzymes did not cause any detectable activation of partially purified prophenoloxidase. Thermolysin and subtilisin mediated activation of prophenoloxidase was inhibited by p-nitrophenyl-p′-guanidobenzoate. Similarly, benzamidine inhibited prophenoloxidase activation catalyzed by thermolysin. Activity measurements reveal the activation of a serine protease prior to prophenoloxidase activation. These results indicate the presence of a precursor form for the serine protease which is responsible for prophenoloxidase activation in Manduca sexta hemolymph.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940050102
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  • 6
    Electronic Resource
    Electronic Resource
    On the mechanism of formation of N-acetyldopamine quinone methide in insect cuticle (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 9 (1988), S. 269-281 
    Details
    ISSN: 0739-4462
    Keywords: phenoloxidase ; quinone methide isomerase ; sclerotization ; tanning ; tautomerization of quinones ; Manduca sexta ; Periplaneta americana ; Sarcophaga bullata ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mechanism of formation of quinone methide from the sclerotizing precursor N-acetyldopamine (NADA) was studied using three different cuticular enzyme systems viz. Sarcophaga bullata larval cuticle, Manduca sexta pharate pupae, and Periplaneta americana presclerotized adult cuticle. All three cuticular samples readily oxidized NADA. During the enzyme-catalyzed oxidation, the majority of NADA oxidized became bound covalently to the cuticle through the side chain with the retention of o-diphenolic function, while a minor amount was recovered as N-acetylnorepinephrine (NANE). Cuticle treated with NADA readily released 2-hydroxy-3′,4′-dihydroxyacetophenone on mild acid hydrolysis confirming the operation of quinone methide sclerotization. Attempts to demonstrate the direct formation of NADA-quinone methide by trapping experiments with N-acetylcysteine surprisingly yielded NADA-quinone-N-acetylcysteine adduct rather than the expected NADA-quinone methide-N-acetylcysteine adduct. These results are indicative of NADA oxidation to NADA-quinone and its subsequent isomerization to NADA-quinone methide. Accordingly, all three cuticular samples exhibited the presence of an isomerase, which catalyzed the conversion of NADA-quinone to NADA-quinone methide as evidenced by the formation of NANE - the water adduct of quinone methide. Thus, in association with phenoloxidase, newly discovered quinone methide isomerase seems to generate quinone methides and provide them for quinone methide sclerotization.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940090403
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  • 7
    Electronic Resource
    Electronic Resource
    On the oxidation of 3,4-dihydroxyphenethyl alcohol and 3,4-dihydroxyphenyl glycol by cuticular enzyme(s) from Sarcophaga bullata (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 10 (1989), S. 13-27 
    Details
    ISSN: 0739-4462
    Keywords: insect cuticle ; catecholamine metabolism ; quinone methide sclerotization ; quinone tanning ; phenoloxidase ; quinone tautomerase ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The catabolic fate of 3,4-dihydroxyphenethyl alcohol (DHPA) and 3,4-dihydroxyphenylethyl glycol (DHPG) in insect cuticle was determined for the first time using cuticular enzyme(s) from Sarcophaga bullata and compared with mushroom tyrosinase-medicated oxidation. Mushroom tyrosinase converted both DHPA and DHPG to their corresponding quinone derivatives, while cuticular enzyme(s) partly converted DHPA to DHPG. Cuticular enzyme(s)-mediated oxidation of DHPA also accompanied the covalent binding of DHPA to the cuticle. Cuticle-DHPA adducts, upon pronase digestion, released peptides that had bound catechols. 3,4-Dihydroxyphenyl-acetaldehyde, the expected product of side chain desaturation of DHPA, was not formed at all. The presence of N-acetylcysteine, a quinone trap, in the reaction mixture containing DHPA and cuticle resulted in the generation of DHPA-quinone-N-acetylcysteine adduct and total inhibition of DHPG formation. The insect enzyme(s) converted DHPG to its quinone at high substrate concentration and to 2-hydroxy-3′,4′-dihydroxyacetophenone at low concentration. They converted exogenously added DHPA-quinone to DHPG, but acted sluggishly on DHPG-quinone. These results are consistent with the enzymatic transformations of phenoloxidase-generated quinones to quinone methides and subsequent nonenzymatic transformation of the latter to the observed products. Thus, quinone methide formation in insect cuticle seems to be caused by the combined action of two enzymes, phenoloxidase and quinone tautomerase, rather than the action of quinone methide-generating phenoloxidase (Sugumaran: Arch Insect Biochem Physiol 8, 73-88, 1988). It is proposed that DHPA and DHPG in combination can be used effectively to examine the participation of (1) quinone, (2) quinone methide, and (3) dehydro derivative intermediates in the metabolism of 4-alkylcatechols for cuticular sclerotization.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940100103
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  • 8
    Electronic Resource
    Electronic Resource
    On the mechanism of side chain oxidation of N-β-alanyldopamine by cuticular enzymes from Sarcophaga bullata (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 15 (1990), S. 255-269 
    Details
    ISSN: 0739-4462
    Keywords: quinone methide sclerotization ; quinone tanning ; β-sclerotization ; catecholamine oxidation ; papiliochrome biosynthesis ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The metabolism of N-β-alanyldopamine (NBAD) by Sarcophaga bullata was investigated. Incubation of NBAD with larval cuticular preparations resulted in the covalent bindings of NBAD to the cuticle and generation of N-β-alanylnorepinephrine (NBANE) as the soluble product. When the reaction was carried out in presence of a powerful quinone trap viz., N-acetylcysteine, NBANE formation was totally abolished; but a new compound characterized as NBAD-quinone-N-acetylcysteine adduct was generated. These results indicate that NBAD quinone is an obligatory intermediate for the biosynthesis of NBANE in sarcophagid cuticle. Accordingly, phenylthiourea - a well-known phenoloxidase inhibitor - completely inhibited the NBANE production even at 5 μM level. A soluble enzyme isolated from cuticle converted exogenously supplied NBAD quinone to NBANE. Chemical considerations indicated that the enzyme is an isomerase and is converting NBAD quinone to its quinone methide which was rapidly and nonenzymatically hydrated to form NBANE. Consistent with this hypothesis is the finding that NBAD quinone methide can be trapped as β-methoxy NBAD by performing the enzymatic reaction in 10% methanol. Moreover, when the reaction was carried out in presence of kynurenine, two diastereoisomeric structures of papiliochrome II-{Nar-[α-3-aminopropionyl amino methyl-3,4-dihydroxybenzyl]-L-kynurenine} could be isolated as byproducts, indicating that the further reactions of NBAD quinone methide with exogenously added nucleophiles are nonenzymatic and nonstereoselective. Based on these results, it is concluded that NBAD is metabolized via NBAD quinone and NBAD quinone methide by the action of phenoloxidase and quinone isomerase respectively. The resultant NBAD quinone methide, being highly reactive, undergoes nonenzymatic and nonstereoselective Michael-1,6-addition reaction with either water (to form NBANE) or other nucleophiles in cuticle to account for the proposed quinone methide sclerotization.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940150406
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  • 9
    Electronic Resource
    Electronic Resource
    Quinone and quinone methide as transient intermediates involved in the side chain hydroxylation of N-acyldopamine derivatives by soluble enzymes from Manduca sexta cuticle (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 16 (1991), S. 123-138 
    Details
    ISSN: 0739-4462
    Keywords: cuticular sclerotization ; N-acylnorepinephrine ; quinone isornerization ; P-hydroxylation ; phenoloxidase ; quinone isomerase ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Proteins solubilized from the pharate cuticle of Manduca sexta were fractionated by ammonium sulfate precipitation and activated by the endogenous enzymes. The activated fraction readily converted exogenously supplied N-acetyldopamine (NADA) to N-acetylnorepinephrine (NANE). Either heat treatment (70°C for 10 min) or addition of phenylthiourea (2.5 μM) caused total inhibition of the side chain hydroxylation. If chemically prepared NADA quinone was supplied instead of NADA to the enzyme solution containing phenylthiourea, it was converted to NANE. Presence of a quinone trap such as N-acetylcysteine in the NADA-cuticular enzyme reaction not only prevented the accumulation of NADA quinone, but also abolished NANE production. In such reaction mixtures, the formation of a new compound characterized as NADA-quinone-N-acetylcysteine adduct could be readily witnessed. These studies indicate that NADA quinone is an intermediate during the side chain hydroxylation of NADA by Manduca cuticular enzyme(s). Since such a conversion calls for the isomerization of NADA quinone to NADA quinone methide and subsequent hydration of NADA quinone methide, attempts were also made to trap the latter compound by performing the enzymatic reaction in methanol. These attempts resulted in the isolation of β-methoxy NADA (NADA quinone methide methanol adduct) as an additional product. Similarly, when the N-β-alanyldopamine (NBAD)-Manduca enzyme reaction was carried out in the presence of L-kynurenine, two diastereoisomers of NBAD quinone methide-kynurenine adduct ( = papiliochrome IIa and IIb) could be isolated. The above results are in agreement with our hypothesis that N-acylnorepinephrine formed in Manduca cuticle is biosynthesized by an indirect route involving intermediary formation of N-acyldopamine quinone and N-acyldopamine quinone methide as established in the case of Sarcophaga bullata and is not produced by the action of a β-hydroxylase.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940160205
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  • 10
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    A computational approach to managing coupled human–environmental systems: the POSEIDON model of ocean fisheries (2018)
    Springer
    Details
    Publication Date: 2018-06-09
    Print ISSN: 1862-4065
    Electronic ISSN: 1862-4057
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Springer
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