Interaction of Phomopsin A with Normal and Subtilisin-Treated Bovine Brain Tubulin |
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Authors: | Asish Ray Chaudhuri Richard F. Ludueñ a |
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Affiliation: | (1) Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78284-7760, USA |
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Abstract: | Tubulin, the major component of microtubules, has a tendency to lose its ability to assemble or to bind to ligands in a time-dependent process known as decay. The decay process also causes tubulin to expose sulfhydryl groups and hydrophobic areas. The antimitotic drug phomopsin A strongly protects the tubulin molecule from decay. Here we have studied the interaction of phomopsin A with tubulin and tubulin which has been treated with subtilisin to remove selectively the C-termini of the and chains (ss). The binding of phomopsin A to tubulin decreases the sulfhydryl titer by approximately 1.0 mol/mol. Selective removal of the peptides from the C-terminal ends does not affect phomopsin A's interaction with tubulin. Moreover, the ss tubulin–phomopsin A complex appears to be more stable than the tubulin–phomopsin A complex as determined by the time-dependent increase in exposure of sulfhydryl groups and hydrophobic areas on tubulin. In fact, phomopsin A inhibits the decay process of ss tubulin completely. This observation raises the possibility of determining the conformtion of this configuration of tubulin. |
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Keywords: | Tubulin phomopsin A alkylation hydrophobic areas C-terminal domain |
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