Nickel Transport and Enzyme Active Site Assembly

Nickel Transport and Enzyme Active Site Assembly 

Synthesis of Ni-containing enzymes requires specific protein factors that are responsible for the transport and incorporation of this ion. In plants, where Ni transport concerns mostly the synthesis of ureases, it has been shown that cultivation in nickel-deficient medium leads to leaflet tip necrosis due to urea accumulation ([30] and references therein). It has been suggested that the optimal coordination for protein Ni transport would be octahedral with two N and at least one O [31]. Interestingly, some plants are hyperaccumulators of Ni and can have as much as 1.2% dry weight Ni in the leaves [30]. In some hyperaccumulators, Ni extracted from vacuoles was found to be complexed by citrate, malate and malonate, the concentrations of the latter two compounds being significantly higher than in nonhyperaccumulators [32]. 

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