Structural modification of proteins by direct electric current from low voltage.
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.
Calzia
Daniela
D
Department of Biology, Università di Genova, 16132 Genova, Italy.
Panfoli
Isabella
I
Ravera
Silvia
S
Dazzi
Elisa
E
Gandolfo
Simona
S
Pepe
Isidoro Mario
IM
Vergani
Laura
L
Morelli
Alessandro M
AM
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
D000596:Amino Acids; D007527:Isoenzymes; D011506:Proteins; D000263:Adenylate Kinase