Inhibitors of phenoloxidase are used routinely to characterise the structural and functional properties of phenoloxidases. Hemocyanin-derived phenoloxidase activity is also sensitive to standard phenoloxidase inhibitors. In this study, we characterise the effects of a number of phenoloxidase inhibitors on hemocyanin-derived phenoloxidase activity from the chelicerate, Limulus polyphemus. Both inhibition type and K(i) values were similar to those observed for hemocyanin-derived phenoloxidase from another chelicerate, Eurypelma californicum. In addition, substrate inhibition was observed at concentrations above 2mM dopamine. The conformation in which two of the inhibitors, namely tropolone and kojic acid, would bind near the Cu(II) centre of hemocyanin is proposed.
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http://dx.doi.org/10.1016/j.cbpb.2012.07.003 | DOI Listing |
Int J Biol Macromol
June 2024
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address:
Hemocyanin, an oxygen-transport protein, is widely distributed in the hemolymph of marine arthropods and mollusks, playing an important role in their physiological processes. Recently, hemocyanin has been recognized as a multifunctional glycoprotein involved in the immunological responses of aquatic invertebrates. Consequently, the link between hemocyanin functions and their potential applications has garnered increased attention.
View Article and Find Full Text PDFComp Biochem Physiol B Biochem Mol Biol
June 2021
Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, RM 7750000, Chile. Electronic address:
Enzymes adapted to cold temperatures are commonly characterized for having higher Michaelis-Menten constants (K) values and lower optimum and denaturation temperature, when compared to other meso or thermophilic enzymes. Phenoloxidase (PO) enzymes are ubiquitous in nature, however, they have not been reported in spiders. It is the oxygen carrier protein hemocyanin (Hc), found at high concentrations in their hemolymph, which displays an inducible PO activity.
View Article and Find Full Text PDFInt J Biol Macromol
May 2019
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong 510300, PR China. Electronic address:
Hemocyanins (Hc), the main protein components of hemolymph in invertebrates, are not only involved in oxygen transport but also linked to non-specific immune responses. In this study, we used abalone (Haliotis diversicolor) Hc to study the basis of its diversified functions through gene, protein, peptides, and phenoloxidase (PO) activity levels. Three complete hemocyanin gene (HdH) sequences were cloned for the first time.
View Article and Find Full Text PDFDev Comp Immunol
September 2018
Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, Wales UK.
Hemocyanin is a multi-functional protein located in the hemolymph (blood) of certain arthropods and molluscs. In addition to its well-defined role in oxygen transport, hemocyanin can be converted into a phenoloxidase-like enzyme. Herein, we tested the antimicrobial properties of horseshoe crab (Limulus polyphemus) hemocyanin-derived phenoloxidase reaction products using broad ranges of phenolic substrates (e.
View Article and Find Full Text PDFDev Comp Immunol
March 2015
Fujian Provincial key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education, Fuzhou 350002, China. Electronic address:
Hemocyanins present in invertebrate hemolymph are multifunctional proteins, responsible for oxygen transport and contributing to innate immunity through phenoloxidase-like activity. In arthropods, hemocyanin has been identified as a source of broad-spectrum antimicrobial peptides during infection. Conversely, no hemocyanin-derived antimicrobial peptides have been reported for molluscs.
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