Antithrombin activity of gold sodium thiomalate.

Gold sodium thiomalate has been shown to inhibit serine esterase enzymes isolated from the lysosomes of white cells. We demonstrate for the first time to our knowledge that gold sodium thiomalate is inhibitory to the serine esterase thrombin in its interaction with washed human platelets, human platelet-rich plasma, and human platelet-poor plasma. Since thrombin is a serine esterase phylogenetically related to the serine esterases elastase and cathepsin G, the most likely mechanism of action is an interaction of the gold thiol complex with one or all of the four cysteine-cysteine disulfide bridges of the thrombin molecule.