Role of free thiol groups in the biological activities of stonustoxin, a lethal factor from stonefish (Synanceja horrida) venom

摘要

Hoon Eng Khoo? Desong Chen and Raymond Yuen. Role of free thiol groups in the biological activities of stonustoxin, a lethal factor from stonefish (Synanceja horrida) venom. Toxicon 36, 469-476, 1998.-Stonustoxin (SNTX) is a two-subunit protein purified from the venom of a stonefish, Synanceja horrida. It has potent lethal activity and is also a membrane poreforming cytolysin. The role of thiol groups in the biological activities of SNTX was investigated. Both the hemolytic and lethal activities of SNTX were potentiated by the reducing agent, dithiothreitol (DTT). The hemolytic activity of SNTX was sensitive to the modification of thiol groups by 5,5'-dithiobis(3-nitrobenzoic acid) (DTNB). The loss of haemolytic activity correlated with the number of thiol groups that were titrated with DTNB. Thiol modification of SNTX with DINE also inhibited its lethality. These inhibitory effects of thiol modification could be reversed by reduction with DTT. It was also found that the haemolytic activity of SNTX could not be inhibited by cholesterol. These observations indicate that free thiol groups play an important role in the haemolytic activity and lethality of SNTX but unlike other thiol-activated cytolysins, SNTX was not inhibited by cholesterol. Thus, SNTX may represent a new class of cytolytic toxin. (C) 1998 Elsevier Science Ltd. Ail rights reserved. [References: 18]