Sb. Han et al., A methylene blue-mediated enzyme electrode for the determination of trace mercury(II), mercury(I), methylmercury, and mercury-glutathione complex, BIOSENS BIO, 16(1-2), 2001, pp. 9-16
A methylene blue-mediated enzyme biosensor has been developed for the detec
tion of inhibitors including mercury(II), mercury(I). methylmercury. and me
rcury-glutathione complex. The inhibition to horseradish peroxidase was app
arently reversible and noncompetitive in the presence of HgCl2 in less than
8 s and irreversibly inactivated when incubated with different concentrati
ons of HgCl2 for 1-8 min. The binding site of horseradish peroxidase with H
gCl2 probably was a cysteine residue -SH. Mercury compounds can be assayed
amperometrically with the detection limits 0.1 ng ml(-1) Hg for HgCl2 and m
ethylmercury, 0.2 ng ml(-1) Hg for Hg-2(NO3)(2) and 1.7 ng ml(-1) Hg for me
rcury-glutathione complex. Inactivation of the immobilized horseradish pero
xidase was displayed in the AFM images of the enzyme membranes. (C) 2001 Pu
blished by Elsevier Science B.V.