Premium
The dipyridyls paraquat and diquat attenuate the interaction of G‐actin with thymosin β 4
Author(s) -
Huff Thomas,
Cappelletti Graziella,
Hannappel Ewald
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00295-6
Subject(s) - paraquat , diquat , thymosin , chemistry , actin , dissociation constant , biophysics , biochemistry , biology , receptor
β‐Thymosins sequester G‐actin and preserve a pool of monomers of actin which constitute an important prerequisite for cellular function of the microfilament system. To study the influence of paraquat binding to G‐actin on the interaction of G‐actin with thymosin β 4 we determined the apparent dissociation constant of the G‐actin‐thymosin β 4 complex in the absence or presence of paraquat using an ultrafiltration assay. Paraquat (1,1′‐dimethyl‐4,4′‐dipyridylium dichloride) attenuates this interaction in a concentration‐ and time‐dependent manner. When exposed to 10 mM paraquat, the apparent dissociation constant increased 10–85‐fold within 15 min to 24 h. After incubation for 24 h even a paraquat concentration as low as 100 μM increased the dissociation constant of the G‐actin‐thymosin β 4 complex from 0.66 μM to 0.82 μM ( P <0.05). Diquat (1,1′‐ethylene‐2,2′‐dipyridylium dibromide) similarly weakens the interaction of G‐actin and β‐thymosins. In none of the experiments was oxidation of the methionine residue or any other modification of thymosin β 4 detected. Therefore we conclude that the dipyridyls paraquat and diquat directly interact with G‐actin and thereby impede the interaction between G‐actin and thymosin β 4 .