The luminescence lifetime of Cu-metallothionein from the fungus Neurospora crassa has been studied by the frequency-domain emission technique. Lifetimes of 10.3 and 3.4,s have been found for the protein in the absence and in the presence of oxygen respectively. Binding of Hg(II) results in a quenching of the luminescence correlated to the shortening of lifetime to 0.3-0.4 us. No quenching by oxygen is found for the Hg(II)-Cu-metallothionein adduct. By analogy to model compounds, luminescence emission is attributed to a triplet excited state of a Cu(I)-to-sulphur charge-transfer complex. The comparison of bimolecular quenching constants for 02 and acrylamide indicates a highly compact structure of the protein.
LUMINESCENCE EMISSION FROM NEUROSPORA COPPER METALLOTHIONEIN - TIME-RESOLVED STUDIES
BELTRAMINI, MARIANO;
1989
Abstract
The luminescence lifetime of Cu-metallothionein from the fungus Neurospora crassa has been studied by the frequency-domain emission technique. Lifetimes of 10.3 and 3.4,s have been found for the protein in the absence and in the presence of oxygen respectively. Binding of Hg(II) results in a quenching of the luminescence correlated to the shortening of lifetime to 0.3-0.4 us. No quenching by oxygen is found for the Hg(II)-Cu-metallothionein adduct. By analogy to model compounds, luminescence emission is attributed to a triplet excited state of a Cu(I)-to-sulphur charge-transfer complex. The comparison of bimolecular quenching constants for 02 and acrylamide indicates a highly compact structure of the protein.
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