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Phenol Oxidase (phenol + oxidase)
Selected AbstractsTurnover of labile and recalcitrant soil carbon differ in response to nitrate and ammonium deposition in an ombrotrophic peatlandGLOBAL CHANGE BIOLOGY, Issue 8 2010PAULINE M. CURREY Abstract The effects of 4 years of simulated nitrogen deposition, as nitrate (NO3,) and ammonium (NH4+), on microbial carbon turnover were studied in an ombrotrophic peatland. We investigated the mineralization of simple forms of carbon using MicroRespÔ measurements (a multiple substrate induced respiration technique) and the activities of four soil enzymes involved in the decomposition of more complex forms of carbon or in nutrient acquisition: N -acetyl-glucosaminidase (NAG), cellobiohydrolase (CBH), acid phosphatase (AP), and phenol oxidase (PO). The potential mineralization of labile forms of carbon was significantly enhanced at the higher N additions, especially with NH4+ amendments, while potential enzyme activities involved in breakdown of more complex forms of carbon or nutrient acquisition decreased slightly (NAG and CBH) or remained unchanged (AP and PO) with N amendments. This study also showed the importance of distinguishing between NO3, and NH4+ amendments, as their impact often differed. It is possible that the limited response on potential extracellular enzyme activity is due to other factors, such as limited exposure to the added N in the deeper soil or continued suboptimal functioning of the enzymes due to the low pH, possibly via the inhibitory effect of low phenol oxidase activity. [source] Interactive effects of elevated CO2, N deposition and climate change on extracellular enzyme activity and soil density fractionation in a California annual grasslandGLOBAL CHANGE BIOLOGY, Issue 10 2005Hugh A. L. Henry Abstract Elevated CO2, N deposition and climate change can alter ecosystem-level nutrient cycling both directly and indirectly. We explored the interactive effects of these environmental changes on extracellular enzyme activity and organic matter fractionation in soils of a California annual grassland. The activities of hydrolases (polysaccharide-degrading enzymes and phosphatase) increased significantly in response to nitrate addition, which coincided with an increase in soluble C concentrations under ambient CO2. Water addition and elevated CO2 had negative but nonadditive effects on the activities of these enzymes. In contrast, water addition resulted in an increase in the activities of lignin-degrading enzymes (phenol oxidase and peroxidase), and a decrease in the free light fraction (FLF) of soil organic matter. Independent of treatment effects, lignin content in the FLF was negatively correlated with the quantity of FLF across all samples. Lignin concentrations were lower in the aggregate-occluded light fraction (OLF) than the FLF, and there was no correlation between percent lignin and OLF quantity, which was consistent with the protection of soil organic matter in aggregates. Elevated CO2 decreased the quantity of OLF and increased the OLF lignin concentration, however, which is consistent with increased degradation resulting from increased turnover of soil aggregates. Overall, these results suggest that the effects of N addition on hydrolase activity are offset by the interactive effects of water addition and elevated CO2, whereas water and elevated CO2 may cause an increase in the breakdown of soil organic matter as a result of their effects on lignin-degrading enzymes and soil aggregation, respectively. [source] Expression, purification, and characterization of pro-phenoloxidase-activating serine protease from Spodoptera lituraARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009Naresh Arora Abstract One of the important trigger molecules for innate immunity is a serine protease that activates zymogen phenol oxidase (PPO). Central to wound healing response is the activation of phenol oxidase zymogen. Molecular characterization of phenol oxidase has been recently reported by us. Here, we report isolation, cloning, expression, and purification of prophenol oxidase activating enzyme 1 (slppae1) from polyphagous pest, Spodoptera litura. SLPPAE1 is induced within 6,h of physical injury. The structural features of the mature polypeptide are reminiscent of other lepidopteran PPAE in having a signal peptide, propeptide, and catalytically active polypeptide. The cDNA has been expressed in Sf21 cells using baculovirus expression vector. Fractionation of expressing Sf21 cells revealed its expression in the membranes. The recombinant protein was solubilized from membranes and purified by Ni-NTA affinity chromatography. The purified enzyme is catalytically active on chromogenic substrate, activates recombinantly expressed prophenol oxidase (PPO) of S. litura, and is sensitive to inhibition by aprotenin. N-terminal sequencing of processed phenol oxidase revealed 11,kDa propeptide instead of in-silico predicted 6,kDa polypeptide. © 2009 Wiley Periodicals, Inc. [source] Crystallization and preliminary X-ray diffraction analysis of the small laccase from Streptomyces coelicolorACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 12 2007Tereza Skálová The small bacterial laccase from the actinobacterium Streptomyces coelicolor which lacks the second of the three domains of the laccases structurally characterized to date was crystallized. This multi-copper phenol oxidase crystallizes in a primitive tetragonal lattice, with unit-cell parameters a = b = 179.8, c = 175.3,Å. The crystals belong to either space group P41212 or P43212. The self-rotation function shows the presence of a noncrystallographic threefold axis in the structure. Phases will be determined from the anomalous signal of the natively present copper ions. [source] The Drosophila PRR GNBP3 assembles effector complexes involved in antifungal defenses independently of its Toll -pathway activation functionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2010Alexey A. Matskevich Abstract The Drosophila Toll -signaling pathway controls the systemic antifungal host response. Gram-negative binding protein 3 (GNBP3), a member of the ,-glucan recognition protein family senses fungal infections and activates this pathway. A second detection system perceives the activity of proteolytic fungal virulence factors and redundantly activates Toll. GNBP3hades mutant flies succumb more rapidly to Candida albicans and to entomopathogenic fungal infections than WT flies, despite normal triggering of the Toll pathway via the virulence detection system. These observations suggest that GNBP3 triggers antifungal defenses that are not dependent on activation of the Toll pathway. Here, we show that GNBP3 agglutinates fungal cells. Furthermore, it can activate melanization in a Toll -independent manner. Melanization is likely to be an essential defense against some fungal infections given that the entomopathogenic fungus Beauveria bassiana inhibits the activity of the main melanization enzymes, the phenol oxidases. Finally, we show that GNBP3 assembles "attack complexes", which comprise phenoloxidase and the necrotic serpin. We propose that Drosophila GNBP3 targets fungi immediately at the inception of the infection by bringing effector molecules in direct contact with the invading microorganisms. [source] | ||||||||||