Inhibition of adenosine triphosphatases by gold

• Published in: Arthritis and rheumatism 1980-04, Vol.23 (4), p.464-470
• Main Author: Nechay, Bohdan R.
• Format: Article
• Language: English
• Subjects: Animals; Ascorbic Acid - pharmacology; Brain - enzymology; Brain - metabolism; Chlorides - metabolism; Dogs; Gold - metabolism; Gold - pharmacology; Gold - poisoning; Gold Compounds; Gold Sodium Thiomalate - metabolism; Kidney - enzymology; Kidney - metabolism; Kidney - ultrastructure; Microsomes - drug effects; Microsomes - enzymology; Microsomes - metabolism; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors
• ISSN: 0004-3591; 1529-0131
• DOI: 10.1002/art.1780230409

Inhibition of adenosine triphosphatase (ATPase) by chlorauric acid (Au3+) and gold sodium thiomalate (Au+) was studied in dog brain and kidney and in human kidney enzyme preparations. Au3+ indiscriminately affected ouabain‐sensitive (Na+ + K+‐dependent) ATPase and ouabain‐insensitive (Mg2+‐dependent) ATPase with concentrations for 50% inhibition (I50) approximately 10‐6 M. The I50 of Au3+ for Na+ + K+ ATPase was several‐fold higher in homogenates than in microsomal fractions. The enzyme was protected by bovine serum albumin. Although Au3+ and Au+ were equipotent against Mg2+ ATPase, Au+ inhibited Na+ + K+ ATPase 2 to 3 times more effectively than did Au3+. The inhibitory action of Au3+ (but not Au+) was potentiated by ascorbic acid, suggesting reduction of Au3+ to Au+ by ascorbic acid. The fractional inhibition of Na+ + K+ ATPase by Au3+ or Au+ was not affected by changing concentrations of NaCl, KCl, MgCl2, ATP, and MgATP. Decreasing pH from 8.0 to 6.8 enhanced both Au+ and Au3+ inhibition. We conclude that gold is one of the most potent nonspecific of Na+ + K+ ATPase, with characteristics differing from other metallic inhibitors of this enzyme system.