Purification, Spectroscopic Characterization and o-Diphenoloxidase Activity of Hemocyanin from a Freshwater Gastropod: Pila globosa

Antibacterial activity of hemocyanin from red swamp crayfish (Procambarus clarkii)

Hemocyanins (HMC): the copper-containing respiratory proteins present in invertebrate hemolymph, which plays many essential roles in the immune system. Currently, little is known about the HMC domains of Procambarus clarkii (P. clarkii) and their function in antimicrobial immune response. In this present study, we comparatively studied the expression pattern of native PcHMC with the three recombinant proteins of variable domains of crayfish hemocyanin (PcHMC-N, N-terminal domain of hemocyanin; PcHMC-T, tyrosinase domain of hemocyanin; PcHMC-C, C-terminal domain of hemocyanin). The results showed that three purified recombinant proteins had a strong binding to various bacteria and lipopolysaccharides that further highly agglutinated. The HMCs recombinant proteins showed strong antibacterial activity against V. parahaemolyticus and S. aureus by bacterial growth inhibition, phenoloxidase (PO) and phagocytosis assays. Specifically, rPcHMC1-T and rPcHMC1-C inhibited both the bacteria efficiently, rPcHMC1-T was highly upregulated the PO activity than the other recombinant proteins. Whereas, recombinant proteins pretreated crayfish hemocytes participated in phagocytosis activity, rPcHMC1-N and rPcHMC1-C proteins had a profound effect than the rPcHMC1-T on S. aureus and V. parahaemolyticus phagocytosis. The crayfish hemocyanin domains clearly exhibited antibacterial and phagocytic activities against both the bacteria, suggesting that its variable domains of hemocyanin have the different function on specific pathogen during the assault of pathogens.

Inhibition effects of benzylideneacetone, benzylacetone, and 4-phenyl-2-butanol on the activity of mushroom tyrosinase

Tyrosinase (EC 1.14.18.1) is the key enzyme of melanin synthesis and fruit-vegetable browning. The inhibition of benzylideneacetone, benzylacetone, and 4-phenyl-2-butanol on mushroom tyrosinase was first investigated. The results shown that these three compounds could effectively inhibit the enzyme activity sharply and the inhibitory effects were determined to be reversible. Their inhibitor concentrations leading to 50% activity lost values were determined to be 1.5, 2.8, and 1.1 mM for monophenolase and 2.0, 0.6, and 0.8 mM for diphenolase, respectively. For the monophenolase activity, all of these three compounds were mixed-type inhibitors, however, only 4-phenyl-2-butanol obviously lengthened the lag time. For the diphenolase activity, benzylideneacetone and benzylacetone were mixed-type inhibitors, while 4-phenyl-2-butanol was a noncompetitive type inhibitor. In conclusion, these compounds exhibited potent antityrosinase activities. This research would provide scientific evidence for the use of benzylideneacetone, benzylacetone, and 4-phenyl-2-butanol as antityrosinase agents.

Diverse immune functions of hemocyanins

Substantial evidence gathered recently has revealed the multiple functionalities of hemocyanin. Contrary to previous claims that this ancient protein is involved solely in oxygen transport within the hemolymph of invertebrates, hemocyanin and hemocyanin-derived peptides have been linked to key aspects of innate immunity, in particular, antiviral and phenoloxidase-like activities. Both phenoloxidase and hemocyanin belong to the family of type-3 copper proteins and share a high degree of sequence homology. While the importance of phenoloxidase in immunity and development is well characterised, the contribution of hemocyanin to biological defence systems within invertebrates is not recognised widely. This review focusses on the conversion of hemocyanin into a phenoloxidase-like enzyme and the array of hemocyanin-derived immune responses documented to date.