| Popis: |
Methanobactin (mb) is a small, copper binding bioactive peptides produced by methanotrophs. The transition between two forms of methane monooxygenase (MMO) expressed by methanotrophs depends on the amount of copper available in the surrounding. In this paper, the bioavailability of copper(Ⅱ) in the presence of different chelating agents to a representative methanotroph, Methylosinus trichosporium 3011 is studied systematically according to the naphthalene oxidation assay. The result shows that purple naphthol diazo complex may be measured at A530, and along with the increase of the concentration of the copper(Ⅱ), eight kinds of chelating agents have effect on the activity of sMMO. The copper bioavailability has been assessed after the changes in sMMO activity is monitored, it means that copper(Ⅱ) can repress the expression of sMMO as well as reduce its activity. The affinity of mb excreted during growth was also measured and the chelate constants of the chelating agents to copper(Ⅱ) are compared. Based on these studies, strongly binding chelating agents (Log K > 16) added into the medium at a concentration of 20uM were able to reduce copper bioavailability. |
