title: Structural modification of proteins by direct electric current from low voltage.
abstract: The interaction of direct electric current (dc) and proteins is a little explored topic. We had reported that exposure of Crotalus atrox venom to dc caused irreversible inactivation of phospholipase A(2) and metalloprotease and that the eukaryote adenylate kinases (AK) precipitate in nondenaturing gel electrophoresis. AK1 displays an elevated percent difference of CHarged versus POlar amino acid content (CH-PO 14). Commercial AK1 and other 17 enzymes with various CH-PO values were exposed in solution to dc (0-0.7 mA) from low voltage (0-10 V), then enzymatic activity was assayed. The enzymes with CH-PO higher than 10.0 were irreversibly inactivated by current exposure; those with CH-PO between +3 and -5 were not. Inactivation was dependent on the ionic strength of the medium and not on the net charge of the protein. Circular dichroic spectroscopy showed a structural modification in some of the inactivated enzymes. CH-PO could be a crucial, although rough, parameter for predicting protein inactivation by low-voltage exposure. The observed effect seems due to the current density. Enzymatic activity maybe a more accurate sensor of conformational changes than circular dichroism spectroscopy. A better understanding of efficacy of many electrical devices utilized in medical practice may follow.
authors.affiliation: Department of Biology, Università di Genova, 16132 Genova, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Calzia
authors.forename: Isabella
authors.initials: I
authors.lastname: Panfoli
authors.forename: Silvia
authors.initials: S
authors.lastname: Ravera
authors.forename: Elisa
authors.initials: E
authors.lastname: Dazzi
authors.forename: Simona
authors.initials: S
authors.lastname: Gandolfo
authors.forename: Isidoro Mario
authors.initials: IM
authors.lastname: Pepe
authors.forename: Laura
authors.initials: L
authors.lastname: Vergani
authors.forename: Alessandro M
authors.initials: AM
authors.lastname: Morelli
mesh_terms: D000263:Adenylate Kinase / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002942:Circular Dichroism; D004560:Electricity; D004789:Enzyme Activation; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007527:Isoenzymes / Q000378:metabolism; D009132:Muscles / Q000201:enzymology; D009994:Osmolar Concentration; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011817:Rabbits; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D000596:Amino Acids; D007527:Isoenzymes; D011506:Proteins; D000263:Adenylate Kinase