title: Contrasting effects of selenite and tellurite on lipoamide dehydrogenase activity suggest a different biological behaviour of the two chalcogens.
abstract: The effects of selenite and tellurite on the mammalian enzyme lipoamide dehydrogenase were compared. Selenite acts as a substrate of lipoamide dehydrogenase in a process requiring the presence of lipoamide. In contrast, tellurite is a potent inhibitor, effective in the low micromolar range. The inhibitory effect of tellurite on lipoamide dehydrogenase is partially reverted by dithiothreitol indicating the participation of the thiol groups of the enzyme. Tellurite, but not selenite, stimulates the diaphorase activity of lipoamide dehydrogenase. In a mitochondrial matrix protein preparation, which contains lipoamide dehydrogenase, an inhibitory action similar to that observed on the purified enzyme was also elicited by tellurite. Human embryonic kidney cells (HEK 293 T) treated with tellurite show a partial inhibition of lipoamide dehydrogenase. In addition to the toxicological implications of tellurium compounds, the reported results suggest that tellurite and its derivatives can be used as potential tools for studying biochemical reactions.
authors.affiliation: Department of Biological Chemistry, University of Padova, Padova, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Folda
authors.forename: Anna
authors.initials: A
authors.lastname: Citta
authors.forename: Guido
authors.initials: G
authors.lastname: Scutari
authors.forename: Alberto
authors.initials: A
authors.lastname: Bindoli
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Rigobello
mesh_terms: D000818:Animals; D008058:Dihydrolipoamide Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D020536:Enzyme Activators / Q000737:chemistry / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D010084:Oxidation-Reduction; D018038:Sodium Selenite / Q000737:chemistry / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013552:Swine; D013691:Tellurium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D020536:Enzyme Activators; D013438:Sulfhydryl Compounds; D008058:Dihydrolipoamide Dehydrogenase; D018038:Sodium Selenite; C026660:tellurous acid; D013691:Tellurium